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Update kubeadm guide and reference pages for 1.6

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Signed-off-by: Joe Beda <joe.github@bedafamily.com>
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Joe Beda
2017-03-13 16:18:17 -07:00
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docs/admin/kubeadm.md
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@@ -13,127 +13,137 @@ Running `kubeadm init` bootstraps a Kubernetes cluster. This consists of the
following steps:
1. kubeadm runs a series of pre-flight checks to validate the system state
before making changes. Some checks only trigger warnings, others are
considered errors and will exit kubeadm until the problem is corrected or
the user specifies `--skip-preflight-checks`.
before making changes. Some checks only trigger warnings, others are
considered errors and will exit kubeadm until the problem is corrected or the
user specifies `--skip-preflight-checks`.
1. kubeadm generates a token that additional nodes can use to register
themselves with the master in future. Optionally, the user can provide a token.
themselves with the master in future. Optionally, the user can provide a
token.
1. kubeadm generates a self-signed CA using openssl to provision identities
for each node in the cluster, and for the API server to secure communication
with clients.
1. kubeadm generates a self-signed CA to provision identities for each component
(including nodes) in the cluster. It also generates client certificates to
be used by various components.
1. Outputting a kubeconfig file for the kubelet to use to connect to the API
server, as well as an additional kubeconfig file for administration.
server, as well as an additional kubeconfig file for administration.
1. kubeadm generates Kubernetes resource manifests for the API server,
controller manager and scheduler, and placing them in
`/etc/kubernetes/manifests`. The kubelet watches this directory for static
resources to create on startup. These are the core components of Kubernetes, and
once they are up and running we can use `kubectl` to set up or manage any
additional components.
1. kubeadm generates Kubernetes Static Pod manifests for the API server,
controller manager and scheduler. It places them in
`/etc/kubernetes/manifests`. The kubelet watches this directory for Pods to
create on startup. These are the core components of Kubernetes. Once they are
up and running kubeadm can set up and manage any additional components.
1. kubeadm installs some add-on components, such as DNS or discovery, via the API
server.
1. kubeadm "taints" the master node so that only control plane components will
run there. It also sets up the RBAC authorization system and writes a
special ConfigMap that is used to bootstrap trust with the kubelets.
Running `kubeadm join` on each node in the cluster consists of the following steps:
1. kubeadm installs installs add-on components via the API server. Right now
this is the internal DNS server and the kube-proxy DaemonSet.
1. Use the token to talk to the API server and securely get the root CA
certificate.
Running `kubeadm join` on each node in the cluster consists of the following
steps:
1. Creates a local key pair. Prepares a certificate signing request (CSR) and
sends that off to the API server for signing.
1. kubeadm downloads root CA information from the API server. It uses the token
to verify the authenticity of that data.
1. Configures the local kubelet to connect to the API server
1. kubeadm creates a local key pair. It prepares a certificate signing request
(CSR) and sends that off to the API server for signing. The bootstrap token
is used to authenticate. The API server is configured to sign this
automatically.
1. kubeadm configures the local kubelet to connect to the API server
## Usage
Fields that support multiple values do so either with comma separation, or by specifying
the flag multiple times.
Fields that support multiple values do so either with comma separation, or by
specifying the flag multiple times.
The kubeadm command line interface is currently in **beta**. We are aiming to
not break any scripted use of the main `kubeadm init` and `kubeadm join`. The
single exception here is the format of the kubeadm config file as detailed
below. That format is still considered alpha and may change.
### `kubeadm init`
It is usually sufficient to run `kubeadm init` without any flags,
but in some cases you might like to override the default behaviour.
Here we specify all the flags that can be used to customise the Kubernetes
installation.
It is usually sufficient to run `kubeadm init` without any flags, but in some
cases you might like to override the default behaviour. Here we specify all the
flags that can be used to customise the Kubernetes installation.
- `--api-advertise-addresses` (multiple values are allowed)
- `--api-external-dns-names` (multiple values are allowed)
- `--api-advertise-address`
By default, `kubeadm init` automatically detects IP addresses and uses
these to generate certificates for the API server. This uses the IP address
of the default network interface. If you would like to access the API server
through a different IP address, or through a hostname, you can override these
defaults with `--api-advertise-addresses` and `--api-external-dns-names`.
For example, to generate certificates that verify the API server at addresses
`10.100.245.1` and `100.123.121.1`, you could use
`--api-advertise-addresses=10.100.245.1,100.123.121.1`. To allow it to be accessed
with a hostname, `--api-external-dns-names=kubernetes.example.com,kube.example.com`
Specifying `--api-advertise-addresses` disables auto detection of IP addresses.
This is the address the API Server will advertise to other members of the
cluster. This is also the address used to construct the suggested `kubeadm
join` line at the end of the init process. If not set (or set to 0.0.0.0) then
IP for the default interface will be used.
- `--cloud-provider`
This address is also added to the certifcate that the API Server uses.
Currently, `kubeadm init` does not provide autodetection of cloud provider.
This means that load balancing and persistent volumes are not supported out
of the box. You can specify a cloud provider using `--cloud-provider`.
Valid values are the ones supported by `controller-manager`, namely `"aws"`,
`"azure"`, `"cloudstack"`, `"gce"`, `"mesos"`, `"openstack"`, `"ovirt"`,
`"rackspace"`, `"vsphere"`. In order to provide additional configuration for
the cloud provider, you should create a `/etc/kubernetes/cloud-config`
file manually, before running `kubeadm init`. `kubeadm` automatically
picks those settings up and ensures other nodes are configured correctly.
The exact format and content of the file `/etc/kubernetes/cloud-config` depends
on the type you specified for `--cloud-provider`; see the appropriate documentation
for your cloud provider for details.
You must also set the `--cloud-provider` and `--cloud-config` parameters
yourself by editing the `/etc/systemd/system/kubelet.service.d/10-kubeadm.conf`
file appropriately.
- `--apiserver-bind-port`
- `--external-etcd-cafile` etcd certificate authority file
- `--external-etcd-endpoints` (multiple values are allowed)
- `--external-etcd-certfile` etcd client certificate file
- `--external-etcd-keyfile` etcd client key file
The port that the API server will bind on. This defaults to 6443.
By default, `kubeadm` deploys a single node etcd cluster on the master
to store Kubernetes state. This means that any failure on the master node
requires you to rebuild your cluster from scratch. Currently `kubeadm init`
does not support automatic deployment of a highly available etcd cluster.
If you would like to use your own etcd cluster, you can override this
behaviour with `--external-etcd-endpoints`. `kubeadm` supports etcd client
authentication using the `--external-etcd-cafile`, `--external-etcd-certfile`
and `--external-etcd-keyfile` flags.
- `--apiserver-cert-extra-sans`
Additional hostnames or IP addresses that should be added to the Subject
Alternate Name section for the certificate that the API Server will use. If you
expose the API Server through a load balancer and public DNS you could specify
this with
```
--apiserver-cert-extra-sans=kubernetes.example.com,kube.example.com,10.100.245.1
```
- `--cert-dir`
The path where to save and store the certificates. The default is
"/etc/kubernetes/pki".
- `--config`
A kubeadm specific [config file](#config-file). This can be used to specify an
extended set of options including passing arbitrary command line flags to the
control plane components.
- `--kubernetes-version` (default 'latest') the kubernetes version to initialise
The **v1.6** version of kubeadm only supports building clusters that are at
least **v1.6.0**. There are many reasons for this including kubeadm's use of
RBAC, the Bootstrap Token system, and enhancements to the Certificates API. With
this flag you can try any future version of Kubernetes. Check [releases
page](https://github.com/kubernetes/kubernetes/releases) for a full list of
available versions.
- `--pod-network-cidr`
For certain networking solutions the Kubernetes master can also play a role in
allocating network ranges (CIDRs) to each node. This includes many cloud providers
and flannel. You can specify a subnet range that will be broken down and handed out
to each node with the `--pod-network-cidr` flag. This should be a minimum of a /16 so
controller-manager is able to assign /24 subnets to each node in the cluster.
If you are using flannel with [this manifest](https://github.com/coreos/flannel/blob/master/Documentation/kube-flannel.yml)
you should use `--pod-network-cidr=10.244.0.0/16`. Most CNI based networking solutions
do not require this flag.
allocating network ranges (CIDRs) to each node. This includes many cloud
providers and flannel. You can specify a subnet range that will be broken down
and handed out to each node with the `--pod-network-cidr` flag. This should be a
minimum of a /16 so controller-manager is able to assign /24 subnets to each
node in the cluster. If you are using flannel with [this
manifest](https://github.com/coreos/flannel/blob/master/Documentation/kube-flannel.yml)
you should use `--pod-network-cidr=10.244.0.0/16`. Most CNI based networking
solutions do not require this flag.
- `--service-cidr` (default '10.96.0.0/12')
You can use the `--service-cidr` flag to override the subnet Kubernetes uses to
assign pods IP addresses. If you do, you will also need to update the
`/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file to reflect this change
else DNS will not function correctly.
`/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file to reflect this
change else DNS will not function correctly.
- `--service-dns-domain` (default 'cluster.local')
By default, `kubeadm init` deploys a cluster that assigns services with DNS names
`<service_name>.<namespace>.svc.cluster.local`. You can use the `--service-dns-domain`
to change the DNS name suffix. Again, you will need to update the
`/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file accordingly else DNS will
not function correctly.
By default, `kubeadm init` deploys a cluster that assigns services with DNS
names `<service_name>.<namespace>.svc.cluster.local`. You can use the
`--service-dns-domain` to change the DNS name suffix. Again, you will need to
update the `/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file
accordingly else DNS will not function correctly.
- `--skip-preflight-checks`
By default, `kubeadm` runs a series of preflight checks to validate the system
By default, kubeadm runs a series of preflight checks to validate the system
before making any changes. Advanced users can use this flag to bypass these if
necessary.
@@ -141,43 +151,110 @@ necessary.
By default, `kubeadm init` automatically generates the token used to initialise
each new node. If you would like to manually specify this token, you can use the
`--token` flag. The token must be of the format `<6 character string>.<16 character string>`.
`--token` flag. The token must be of the format `[a-z0-9]{6}\.[a-z0-9]{16}`. A
compatible random token can be generated `kubeadm token generate`. Tokens can
be managed through the API after the cluster is created. See the [section on
managing tokens](#manage-tokens) below.
- `--kubernetes-version` (default 'latest') the kubernetes version to initialise
- `--token-ttl`
`kubeadm` was originally built for Kubernetes version **v1.4.0**, older versions are not
supported. The current version of `kubeadm` requires at least **v1.6.0-alpha.3** due to RBAC being enabled by default.
With this flag you can try any future version, e.g. **v1.6.0-beta.1**
whenever it comes out (check [releases page](https://github.com/kubernetes/kubernetes/releases)
for a full list of available versions).
This sets an expiration time for the token. This is specified as a duration
from the current time. After this time the token will no longer be valid and
will be removed. A value of 0 specifies that the token never expires. 0 is the
default. See the [section on managing tokens](#manage-tokens) below.
### `kubeadm join`
When you use kubeadm join, you must supply the token used to secure cluster
boostrap as a mandatory flag, and the master IP address as a mandatory argument.
When joining a kubeadm initialized cluster, we need to establish bidirectional
trust. This is split into discovery (having the Node trust the Kubernetes
master) and TLS bootstrap (having the Kubernetes master trust the Node).
There are 2 main schemes for discovery. The first is to use a shared token along
with the IP address of the API server. The second is to provide a file (a subset
of the standard kubeconfig file). This file can be a local file or downloaded
via an HTTPS URL. The forms are `kubeadm join --discovery-token
abcdef.1234567890abcdef 1.2.3.4:6443`, `kubeadm join --discovery-file
path/to/file.conf` or `kubeadm join --discovery-file https://url/file.conf`.
Only one form can be used. If the discovery information is loaded from a URL,
HTTPS must be used and the host installed CA bundle is used to verify the
connection.
The TLS bootstrap mechanism is also driven via a shared token. This is used to
temporarily authenticate with the Kubernetes master to submit a certificate
signing request (CSR) for a locally created key pair. By default kubeadm will
set up the Kubernetes master to automatically approve these signing requests.
This token is passed in with the `--tls-bootstrap-token abcdef.1234567890abcdef`
flag.
Often times the same token is use for both parts. In this case, the `--token` flag
can be used instead of specifying the each token individually.
Here's an example on how to use it:
`kubeadm join --token=the_secret_token 192.168.1.1`
`kubeadm join --token=abcdef.1234567890abcdef 192.168.1.1:6443`
Specific options:
- `--config`
Extended options a specified in the [kubeadm specific config file](#config-file).
- `--skip-preflight-checks`
By default, `kubeadm` runs a series of preflight checks to validate the system
By default, kubeadm runs a series of preflight checks to validate the system
before making any changes. Advanced users can use this flag to bypass these if
necessary.
- `--discovery-file`
A local file path or HTTPS URL. The file specified must be a kubeconfig file
with nothing but an unnamed cluster entry. This is used to find both the
location of the API server to join along with a root CA bundle to use when
talking to that server.
This might look something like this:
``` yaml
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: <really long certificate data>
server: https://10.138.0.2:6443
name: ""
contexts: []
current-context: ""
kind: Config
preferences: {}
users: []
```
- `--discovery-token`
The discovery token is used along with the address of the API server (as an
unnamed argument) to download and verify information about the cluster. The
most critical part of the cluster information is the root CA bundle used to
verify the identity of the server during subsequent TLS connections.
- `--tls-bootstrap-token`
The token used to authenticate to the API server for the purposes of TLS
bootstrapping.
- `--token=<token>`
By default, when `kubeadm init` runs, a token is generated and revealed in the output.
That's the token you should use here.
Often times the same token is used for both `--discovery-token` and
`--tls-bootstrap-token`. This option specifies the same token for both. Other
flags override this flag if present.
## Using kubeadm with a configuration file {#config-file}
## Using kubeadm with a configuration file
**WARNING:** While kubeadm command line interface is in beta, the config file is
still considered alpha and may change in future versions.
WARNING: kubeadm is in alpha and the configuration API syntax will likely change before GA.
It's possible to configure kubeadm with a configuration file instead of command line flags, and some more advanced features may only be
available as configuration file options.
It's possible to configure kubeadm with a configuration file instead of command
line flags, and some more advanced features may only be available as
configuration file options. This file is passed in to the `--config` option on
both `kubeadm init` and `kubeadm join`.
### Sample Master Configuration
@@ -185,16 +262,7 @@ available as configuration file options.
apiVersion: kubeadm.k8s.io/v1alpha1
kind: MasterConfiguration
api:
advertiseAddresses:
- <address1|string>
- <address2|string>
bindPort: <int>
externalDNSNames:
- <dnsname1|string>
- <dnsname2|string>
authorizationMode: <string>
cloudProvider: <string>
discovery:
advertiseAddress: <address|string>
bindPort: <int>
etcd:
endpoints:
@@ -203,25 +271,29 @@ etcd:
caFile: <path|string>
certFile: <path|string>
keyFile: <path|string>
kubernetesVersion: <string>
networking:
dnsDomain: <string>
serviceSubnet: <cidr>
podSubnet: <cidr>
secrets:
givenToken: <token|string>
apiServerExtraArgs: {
<argument>: <value|string>,
<argument>: <value|string>,
}
controllerManagerExtraArgs: {
<argument>: <value|string>,
<argument>: <value|string>,
}
schedulerExtraArgs: {
<argument>: <value|string>,
<argument>: <value|string>,
}
kubernetesVersion: <string>
cloudProvider: <string>
authorizationMode: <string>
token: <string>
tokenTTL: <time duration>
selfHosted: <bool>
apiServerExtraArgs:
<argument>: <value|string>
<argument>: <value|string>
controllerManagerExtraArgs:
<argument>: <value|string>
<argument>: <value|string>
schedulerExtraArgs:
<argument>: <value|string>
<argument>: <value|string>
apiServerCertSANs:
- <name1|string>
- <name2|string>
certificatesDir: <string>
```
### Sample Node Configuration
@@ -229,53 +301,94 @@ schedulerExtraArgs: {
```yaml
apiVersion: kubeadm.k8s.io/v1alpha1
kind: NodeConfiguration
apiPort: <int>
discoveryPort: <int>
masterAddresses:
- <master1>
secrets:
givenToken: <token|string>
caCertPath: <path|string>
discoveryFile: <path|string>
discoveryToken: <string>
# Currently only the first server is used as a target for the cluster
# bootstrap flow.
discoveryTokenAPIServers:
- <address|string>
- <address|string>
tlsBootstrapToken: <string>
```
## Managing Tokens {#manage-tokens}
You can use the `kubeadm` tool to manage tokens on a running cluster. It will
automatically grab the default admin credentials on a master from a `kubeadm`
created cluster (`/etc/kubernetes/admin.conf`). You can specify an alternate
kubeconfig file for credentials with the `--kubeconfig` to the following
commands.
* `kubeadm token list` Lists the tokens along with when they expire and what the
approved usages are.
* `kubeadm token create` Creates a new token.
* `--description` Set the description on the new token.
* `--ttl duration` Set expiration time of the token as a delta from "now".
Default is 0 for no expiration.
* `--usages` Set the ways that the token can be used. The default is
`signing,authentication`. These are the usages as described above.
* `kubeadm token delete <token id>|<token id>.<token secret>` Delete a token.
The token can either be identified with just an ID or with the entire token
value. Only the ID is used; the token is still deleted if the secret does not
match.
In addition, you can use the `kubeadm token generate` command to locally creates
a new token. This token is of the correct form for specifying with the
`--token` argument to `kubeadm init`.
For the gory details on how the tokens are implemented (including managing them
outside of kubeadm) see the [Bootstrap Token
docs](/docs/admin/bootstrap-tokens/).
## Automating kubeadm
Rather than copying the token you obtained from `kubeadm init` to each node, as
in the basic `kubeadm` tutorials, you can parallelize the token distribution for
easier automation. To implement this automation, you must know the IP address
that the master will have after it is started.
in the [basic kubeadm tutorial](docs/getting-started-guides/kubeadm/), you can
parallelize the token distribution for easier automation. To implement this
automation, you must know the IP address that the master will have after it is
started.
1. Generate a token. This token must have the form `<6 character string>.<16 character string>`.
1. Generate a token. This token must have the form `<6 character string>.<16
character string>`. More formally, it must match the regex
`[a-z0-9]{6}\.[a-z0-9]{16}`.
Kubeadm can pre-generate a token for you:
Kubeadm can generate a token for you:
```console
$ kubeadm token generate
``` bash
kubeadm token generate
```
1. Start both the master node and the worker nodes concurrently with this token. As they come up they should find each other and form the cluster.
1. Start both the master node and the worker nodes concurrently with this token.
As they come up they should find each other and form the cluster. The same
`--token` argument can be used on both `kubeadm init` and `kubeadm join`.
Once the cluster is up, you can grab the admin credentials from the master node at `/etc/kubernetes/admin.conf` and use that to talk to the cluster.
Once the cluster is up, you can grab the admin credentials from the master node
at `/etc/kubernetes/admin.conf` and use that to talk to the cluster.
## Environment variables
There are some environment variables that modify the way that `kubeadm` works. Most users will have no need to set these.
These environment variables are a short-term solution, eventually they will be integrated in the kubeadm configuration file.
There are some environment variables that modify the way that kubeadm works.
Most users will have no need to set these. These environment variables are a
short-term solution, eventually they will be integrated in the kubeadm
configuration file.
| Variable | Default | Description |
| --- | --- | --- |
| `KUBE_KUBERNETES_DIR` | `/etc/kubernetes` | Where most configuration files are written to and read from |
| `KUBE_HOST_PKI_PATH` | `/etc/kubernetes/pki` | Directory for master PKI assets |
| `KUBE_HOST_ETCD_PATH` | `/var/lib/etcd` | Local etcd state for Kubernetes cluster |
| `KUBE_HYPERKUBE_IMAGE` | `` | If set, use a single hyperkube image with this name. If not set, individual images per server component will be used. |
| `KUBE_DISCOVERY_IMAGE` | `gcr.io/google_containers/kube-discovery-<arch>:1.0` | The bootstrap discovery helper image to use. |
| `KUBE_ETCD_IMAGE` | `gcr.io/google_containers/etcd-<arch>:2.2.5` | The etcd container image to use. |
| `KUBE_HYPERKUBE_IMAGE` | | If set, use a single hyperkube image with this name. If not set, individual images per server component will be used. |
| `KUBE_ETCD_IMAGE` | `gcr.io/google_containers/etcd-<arch>:3.0.17` | The etcd container image to use. |
| `KUBE_REPO_PREFIX` | `gcr.io/google_containers` | The image prefix for all images that are used. |
If you want to use kubeadm with an http proxy, you may need to configure it to support http_proxy, https_proxy, or no_proxy.
If you want to use kubeadm with an http proxy, you may need to configure it to
support http_proxy, https_proxy, or no_proxy.
For example, if your kube master node IP address is 10.18.17.16 and you have proxy support both http/https on 10.18.17.16 port 8080, you can use the following command:
You can using following command
For example, if your kube master node IP address is 10.18.17.16 and you have a
proxy which supports both http/https on 10.18.17.16 port 8080, you can use the
following command:
```bash
export PROXY_PORT=8080
@@ -287,10 +400,14 @@ export HTTPS_PROXY=$http_proxy
export no_proxy="localhost,127.0.0.1,localaddress,.localdomain.com,example.com,10.18.17.16"
```
Remember to change ```proxy_ip``` and add a kube master node IP address to ```no_proxy```.
Remember to change `proxy_ip` and add a kube master node IP address to
`no_proxy`.
## Releases and release notes
If you already have kubeadm installed and want to upgrade, run `apt-get update && apt-get upgrade` or `yum update` to get the latest version of kubeadm.
If you already have kubeadm installed and want to upgrade, run `apt-get update
&& apt-get upgrade` or `yum update` to get the latest version of kubeadm.
Refer to the [CHANGELOG.md](https://github.com/kubernetes/kubeadm/blob/master/CHANGELOG.md) for more information.
Refer to the
[CHANGELOG.md](https://github.com/kubernetes/kubeadm/blob/master/CHANGELOG.md)
for more information.
docs/getting-started-guides/kubeadm.md
+263 -202
View File
@@ -13,9 +13,10 @@ li>.highlighter-rouge {position:relative; top:3px;}
## Overview
This quickstart shows you how to easily install a secure Kubernetes cluster on
machines running Ubuntu 16.04, CentOS 7 or HypriotOS v1.0.1+. The installation
uses a tool called _kubeadm_ which is part of Kubernetes.
This quickstart shows you how to easily install a Kubernetes cluster on machines
running Ubuntu 16.04, CentOS 7 or HypriotOS v1.0.1+. The installation uses a
tool called _kubeadm_ which is part of Kubernetes. As of v1.6, kubeadm aims to
create a secure cluster of of the box via mechanisms such as RBAC.
This process works with local VMs, physical servers and/or cloud servers. It is
simple enough that you can easily integrate its use into your own automation
@@ -24,25 +25,42 @@ simple enough that you can easily integrate its use into your own automation
See the full [kubeadm reference](/docs/admin/kubeadm) for information on all
kubeadm command-line flags and for advice on automating kubeadm itself.
**The kubeadm tool is currently in alpha but please try it out and give us
[feedback](/docs/getting-started-guides/kubeadm/#feedback)! Be sure to read the
[limitations](#limitations); in particular note that kubeadm doesn't have great
support for automatically configuring cloud providers. Please refer to the
specific cloud provider documentation or use another provisioning system.**
kubeadm assumes you have a set of machines (virtual or real) that are up and
running. It is designed to be part of a large provisioning system - or just for
easy manual provisioning. kubeadm is a great choice where you have your own
infrastructure (e.g. bare metal), or where you have an existing orchestration
system (e.g. Puppet) that you have to integrate with.
If you are not constrained, there are some other tools built to give you
If you are not constrained, there are other higher-level tools built to give you
complete clusters:
* On GCE, [Google Container Engine](https://cloud.google.com/container-engine/)
gives you one-click Kubernetes clusters
* On AWS, [kops](https://github.com/kubernetes/kops) makes cluster installation
and management easy (and supports high availability)
and management easy. kops supports building high availability clusters (a
feature that kubeadm is currently lacking but is building toward).
### kubeadm Maturity
| Aspect | Maturity Level
|--------|---------------
| Command line UX | beta
| Config file | alpha
| Selfhosting | alpha
| `kubeadm alpha` commands | alpha
| Implementation | alpha
The experience for the command line is currently in beta and we are trying hard
not to change command line flags and break that flow. Other parts of the
experience are still under active development. Specifically, kubeadm relies on
some features (bootstrap tokens, cluster signing), that are still considered
alpha. The implementation may change as the tool evolves to support easy
upgrades and high availability (HA). Any commands under `kubeadm alpha` (not
documented here) are, of course, alpha.
**Be sure to read the [limitations](#limitations)**. Specifically, configuring
cloud providers is difficult. Upgrades are also not well documented or
particularly easy.
## Prerequisites
@@ -65,8 +83,9 @@ complete clusters:
You will install the following packages on all the machines:
* `docker`: the container runtime, which Kubernetes depends on. v1.11.2 is
recommended, but v1.10.3 and v1.12.1 are known to work as well.
* `docker`: the container runtime, which Kubernetes depends on. v1.12 is
recommended, but v1.10 and v1.11 are known to work as well. v1.13 and 17.03+
have not yet been tested and verified by the Kubernetes node team.
* `kubelet`: the most core component of Kubernetes. It runs on all of the
machines in your cluster and does things like starting pods and containers.
* `kubectl`: the command to control the cluster once it's running. You will only
@@ -74,9 +93,9 @@ You will install the following packages on all the machines:
well.
* `kubeadm`: the command to bootstrap the cluster.
NOTE: If you already have kubeadm installed, you should do a `apt-get update &&
**Note:** If you already have kubeadm installed, you should do a `apt-get update &&
apt-get upgrade` or `yum update` to get the latest version of kubeadm. See the
reference doc if you want to read about the different [kubeadm
kubeadm release notes if you want to read about the different [kubeadm
releases](https://github.com/kubernetes/kubeadm/blob/master/CHANGELOG.md)
For each host in turn:
@@ -88,7 +107,7 @@ For each host in turn:
``` bash
apt-get update && apt-get install -y apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
cat <<EOF > /etc/apt/sources.list.d/kubernetes.list
cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
apt-get update
@@ -97,7 +116,7 @@ For each host in turn:
apt-get install -y kubelet kubeadm kubectl kubernetes-cni
```
If the machine is running CentOS, run:
* If the machine is running CentOS, run:
``` bash
cat <<EOF > /etc/yum.repos.d/kubernetes.repo
@@ -121,36 +140,16 @@ kubeadm to tell it what to do.
Note: Disabling SELinux by running `setenforce 0` is required in order to allow
containers to access the host filesystem, which is required by pod networks for
example. You have to do this until kubelet can handle SELinux better.
example. You have to do this until SELinux support is improved in the kubelet.
### (2/4) Initializing your master
The master is the machine where the "control plane" components run, including
etcd (the cluster database) and the API server (which the kubectl CLI
communicates with). All of these components run in pods started by kubelet and
the following images are required and will be automatically pulled by kubelet
if they are absent while `kubeadm init` is initializing your master:
| Image Name | Version |
|---|---|
| gcr.io/google_containers/kube-proxy-amd64 | v1.5.3
| gcr.io/google_containers/kube-controller-manager-amd64 | v1.5.3
| gcr.io/google_containers/kube-scheduler-amd64 | v1.5.3
| gcr.io/google_containers/kube-apiserver-amd64 | v1.5.3
| gcr.io/google_containers/etcd-amd64 | 3.0.14-kubeadm
| gcr.io/google_containers/kube-discovery-amd64 | 1.0
| gcr.io/google_containers/pause-amd64 | 3.0
Right now you can't run `kubeadm init` twice without tearing down the cluster in
between, see [Tear down](#tear-down).
If you try to run `kubeadm init` and your machine is in a state that is
incompatible with starting a Kubernetes cluster, kubeadm will warn you about
things that might not work or it will error out for unsatisfied mandatory
requirements.
communicates with).
To initialize the master, pick one of the machines you previously installed
kubelet and kubeadm on, and run:
kubeadm on, and run:
``` bash
kubeadm init
@@ -158,67 +157,109 @@ kubeadm init
**Note:** this will autodetect the network interface to advertise the master on
as the interface with the default gateway. If you want to use a different
interface, specify `--api-advertise-addresses <ip-address>` argument to `kubeadm
interface, specify `--apiserver-advertise-address <ip-address>` argument to `kubeadm
init`.
If you want to use [flannel](https://github.com/coreos/flannel) as the pod
network, specify `--pod-network-cidr 10.244.0.0/16` if you're using the
daemonset manifest below. _However, please note that this is not required for
any other networks besides Flannel._
There are pod network implementations where the master also plays a role in
allocating a set of network address space for each node. When using
[flannel](https://github.com/coreos/flannel) as the [pod network](#pod-network)
(described in step 3), specify `--pod-network-cidr 10.244.0.0/16`. _This is not
required for any other networks besides Flannel._
Please refer to the [kubeadm reference doc](/docs/admin/kubeadm/) if you want to
read more about the flags `kubeadm init` provides.
This will download and install the cluster database and "control plane"
`kubeadm init` will first run a series of prechecks to ensure that the machine
is ready to run Kubernetes. It will expose warnings and exit on errors. It
will then download and install the cluster database and "control plane"
components. This may take several minutes.
You can't run `kubeadm init` twice without tearing down the cluster in between,
see [Tear Down](#tear-down).
The output should look like:
```
[kubeadm] WARNING: kubeadm is in alpha, please do not use it for production clusters.
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[init] Using Kubernetes version: v1.6.0
[init] Using Authorization mode: RBAC
[preflight] Running pre-flight checks
[init] Using Kubernetes version: v1.5.1
[tokens] Generated token: "064158.548b9ddb1d3fad3e"
[certificates] Generated Certificate Authority key and certificate.
[certificates] Generated API Server key and certificate
[certificates] Generated Service Account signing keys
[certificates] Created keys and certificates in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[preflight] Starting the kubelet service
[certificates] Generated CA certificate and key.
[certificates] Generated API server certificate and key.
[certificates] API Server serving cert is signed for DNS names [kubeadm-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.138.0.4]
[certificates] Generated API server kubelet client certificate and key.
[certificates] Generated service account token signing key and public key.
[certificates] Generated front-proxy CA certificate and key.
[certificates] Generated front-proxy client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[apiclient] Created API client, waiting for the control plane to become ready
[apiclient] All control plane components are healthy after 61.317580 seconds
[apiclient] All control plane components are healthy after 16.772251 seconds
[apiclient] Waiting for at least one node to register and become ready
[apiclient] First node is ready after 6.556101 seconds
[apiclient] Creating a test deployment
[apiclient] First node is ready after 5.002536 seconds
[apiclient] Test deployment succeeded
[token-discovery] Created the kube-discovery deployment, waiting for it to become ready
[token-discovery] kube-discovery is ready after 6.020980 seconds
[token] Using token: <token>
[apiconfig] Created RBAC rules
[addons] Created essential addon: kube-proxy
[addons] Created essential addon: kube-dns
Your Kubernetes master has initialized successfully!
To start using your cluster, you need to run (as a regular user):
sudo cp /etc/kubernetes/admin.conf $HOME/
sudo chown $(id -u):$(id -g) $HOME/admin.conf
export KUBECONFIG=$HOME/admin.conf
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
http://kubernetes.io/docs/admin/addons/
http://kubernetes.io/docs/admin/addons/
You can now join any number of machines by running the following on each node:
You can now join any number of machines by running the following on each node
as root:
kubeadm join --token=<token> <master-ip>
kubeadm join --token <token> <master-ip>:<master-port>
```
Make a record of the `kubeadm join` command that `kubeadm init` outputs. You
will need this in a moment. The key included here is secret, keep it safe
&mdash; anyone with this key can add authenticated nodes to your cluster.
will need this in a moment.
The key is used for mutual authentication between the master and the joining nodes.
The token is used for mutual authentication between the master and the joining
nodes. The token included here is secret, keep it safe &mdash; anyone with this
token can add authenticated nodes to your cluster. These tokens can be listed,
created and deleted with the `kubeadm token` command. See the [reference
guide](/docs/admin/kubeadm/#manage-tokens).
#### Master Images
All of these components run in pods started by kubelet and the following images
are required and will be automatically pulled by kubelet if they are absent
while `kubeadm init` is initializing your master:
| Image Name | Version |
|---|---|
| gcr.io/google_containers/kube-apiserver-amd64 | v1.6.0
| gcr.io/google_containers/kube-controller-manager-amd64 | v1.6.0
| gcr.io/google_containers/kube-scheduler-amd64 | v1.6.0
| gcr.io/google_containers/kube-proxy-amd64 | v1.6.0
| gcr.io/google_containers/etcd-amd64 | 3.0.17
| gcr.io/google_containers/pause-amd64 | 3.0
| gcr.io/google_containers/k8s-dns-sidecar-amd64 | 1.14.1
| gcr.io/google_containers/k8s-dns-kube-dns-amd64 | 1.14.1
| gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64 | 1.14.1
#### Master Isolation
By default, your cluster will not schedule pods on the master for security
reasons. If you want to be able to schedule pods on the master, for example if
you want a single-machine Kubernetes cluster for development, run:
reasons. If you want to be able to schedule pods on the master, e.g a
single-machine Kubernetes cluster for development, run:
``` bash
kubectl taint nodes --all dedicated-
kubectl taint nodes --all node-role.kubernetes.io/master-
```
With output looking something like:
@@ -229,24 +270,28 @@ taint key="dedicated" and effect="" not found.
taint key="dedicated" and effect="" not found.
```
This will remove the "dedicated" taint from any nodes that have it, including
the master node, meaning that the scheduler will then be able to schedule pods
everywhere.
This will remove the `node-role.kubernetes.io/master` taint from any nodes that
have it, including the master node, meaning that the scheduler will then be able
to schedule pods everywhere.
### (3/4) Installing a pod network
### (3/4) Installing a pod network {#pod-network}
You must install a pod network add-on so that your pods can communicate with
each other.
**It is necessary to do this before you try to deploy any applications to your
cluster. Also, kube-dns, a helper service, will no start up before a network is
installed. Note also that kubeadm only supports CNI based networks and therefore
kubenet based networks will not work.**
**The network must be deployed before any applications. Also, kube-dns, a
helper service, will not start up before a network is installed. kubeadm only
supports CNI based networks (and does not support kubenet).**
Several projects provide Kubernetes pod networks using CNI, some of which also
support [Network Policy](/docs/user-guide/networkpolicies/). See the [add-ons
page](/docs/admin/addons/) for a complete list of available network add-ons.
**New for Kubernetes 1.6:** kubeadm 1.6 sets up a more secure cluster by
default. As such it uses RBAC to grant limited privileges to workloads running
on the cluster. This includes networking integrations. As such, ensure that
you are using a network system that has been updated to run with 1.6 and RBAC.
You can install a pod network add-on with the following command:
``` bash
@@ -258,127 +303,76 @@ should only install one pod network per cluster.
If you are on another architecture than amd64, you should use the flannel
overlay network as described in [the multi-platform
section](#kubeadm-is-multi-platform)
section](#multi-platform)
NOTE: You can install **only one** pod network per cluster.
Once a pod network has been installed, you can confirm that it is working by
checking that the kube-dns pod is `Running` in the output of `kubectl get pods
--all-namespaces`.
And once the kube-dns pod is up and running, you can continue by joining your
checking that the kube-dns pod is Running in the output of `kubectl get pods
--all-namespaces`. And once the kube-dns pod is up and running, you can continue by joining your
nodes.
You may have trouble in the configuration if you see the following statuses
```
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system canal-node-f0lqp 2/3 RunContainerError 2 48s
kube-system canal-node-77d0h 2/3 CrashLoopBackOff 3 3m
kube-system kube-dns-2924299975-7q1vq 0/4 ContainerCreating 0 15m
```
The three statuses ```RunContainerError``` and ```CrashLoopBackOff``` and
```ContainerCreating``` are very common.
To help diagnose what happened, you can use the following command to check what
is in the logs:
``` bash
kubectl describe -n kube-system po {YOUR_POD_NAME}
```
Do not using kubectl logs. If you run:
``` bash
kubectl logs -n kube-system canal-node-f0lqp
```
You will got the following error:
```
Error from server (BadRequest): the server rejected our request for an unknown reason (get pods canal-node-f0lqp)
```
The ```kubectl describe``` comand gives you more details about what went wrong.
``` bash
kubectl describe -n kube-system po kube-dns-2924299975-1l2t7
```
The events should show something like this:
```
2m 2m 1 {kubelet nac} spec.containers{flannel} Warning Failed Failed to start container with docker id 927e7ccdc32b with error: Error response from daemon: {"message":"chown /etc/resolv.conf: operation not permitted"}
```
Or this:
```
6m 1m 191 {kubelet nac} Warning FailedSync Error syncing pod, skipping: failed to "SetupNetwork" for "kube-dns-2924299975-1l2t7_kube-system" with SetupNetworkError: "Failed to setup network for pod \"kube-dns-2924299975-1l2t7_kube-system(dee8ef21-fbcb-11e6-ba19-38d547e0006a)\" using network plugins \"cni\": open /run/flannel/subnet.env: no such file or directory; Skipping pod"
```
You can then do some Google searches on the error messages, which may help you
to find some solutions.
If your network is not working or kube-dns is not in the Running state, check
out the [troubleshooting secion](#pod-network-trouble) below.
### (4/4) Joining your nodes
The nodes are where your workloads (containers and pods, etc) run. If you want
to add any new machines as nodes to your cluster, for each machine: SSH to that
machine, become root (e.g. `sudo su -`) and run the command that was output by
`kubeadm init`. For example:
The nodes are where your workloads (containers and pods, etc) run. To add new nodes to your cluster do the following for each machine:
``` bash
kubeadm join --token <token> <master-ip>
```
* SSH to the machine
* Become root (e.g. `sudo su -`)
* Run the command that was output by `kubeadm init`. For example:
``` bash
kubeadm join --token <token> <master-ip>:<master-port>
```
The output should look something like:
```
[kubeadm] WARNING: kubeadm is in alpha, please do not use it for production clusters.
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[preflight] Running pre-flight checks
[preflight] Starting the kubelet service
[tokens] Validating provided token
[discovery] Created cluster info discovery client, requesting info from "http://192.168.x.y:9898/cluster-info/v1/?token-id=f11877"
[discovery] Cluster info object received, verifying signature using given token
[discovery] Cluster info signature and contents are valid, will use API endpoints [https://192.168.x.y:6443]
[bootstrap] Trying to connect to endpoint https://192.168.x.y:6443
[bootstrap] Detected server version: v1.5.1
[bootstrap] Successfully established connection with endpoint "https://192.168.x.y:6443"
[discovery] Trying to connect to API Server "10.138.0.4:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://10.138.0.4:6443"
[discovery] Cluster info signature and contents are valid, will use API Server "https://10.138.0.4:6443"
[discovery] Successfully established connection with API Server "10.138.0.4:6443"
[bootstrap] Detected server version: v1.6.0-beta.3
[bootstrap] The server supports the Certificates API (certificates.k8s.io/v1beta1)
[csr] Created API client to obtain unique certificate for this node, generating keys and certificate signing request
[csr] Received signed certificate from the API server:
Issuer: CN=kubernetes | Subject: CN=system:node:yournode | CA: false
Not before: 2016-12-15 19:44:00 +0000 UTC Not After: 2017-12-15 19:44:00 +0000 UTC
[csr] Generating kubelet configuration
[csr] Received signed certificate from the API server, generating KubeConfig...
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
Node join complete:
* Certificate signing request sent to master and response
received.
received.
* Kubelet informed of new secure connection details.
Run 'kubectl get nodes' on the master to see this machine join.
```
A few seconds later, you should notice that running `kubectl get nodes` on the
master shows a cluster with as many machines as you created.
A few seconds later, you should notice this node in the output from `kubectl get
nodes` when run on the master.
### (Optional) Controlling your cluster from machines other than the master
In order to get a kubectl on your laptop for example to talk to your cluster,
you need to copy the `KubeConfig` file from your master to your laptop like
this:
In order to get a kubectl on some other computer (e.g. laptop) to talk to your
cluster, you need to copy the kubeconfig file from your master to your
workstation like this:
``` bash
scp root@<master ip>:/etc/kubernetes/admin.conf .
kubectl --kubeconfig ./admin.conf get nodes
```
**Note:** If you are using GCE, instances, by default, disable ssh access for
root. First log in to the machine, copy the file someplace that can be accessed
and then use [`gcloud compute
copy-files`](https://cloud.google.com/sdk/gcloud/reference/compute/copy-files)
### (Optional) Connecting to the API Server
If you want to connect to the API Server for viewing the dashboard (note: the
dashboard isn't deployed by default) from outside the cluster for example, you
can use `kubectl proxy`:
If you want to connect to the API Server from outside the cluster you can use
`kubectl proxy`:
``` bash
scp root@<master ip>:/etc/kubernetes/admin.conf .
@@ -389,11 +383,13 @@ You can now access the API Server locally at `http://localhost:8001/api/v1`
### (Optional) Installing a sample application
As an example, install a sample microservices application, a socks shop, to put
your cluster through its paces. Note that this demo does only work on `amd64`.
To learn more about the sample microservices app, see the [GitHub
Now it is time to take your new cluster for a test drive. Sock Shop is a sample
microservices application that shows how to run and connect a set of services on
Kubernetes. To learn more about the sample microservices app, see the [GitHub
README](https://github.com/microservices-demo/microservices-demo).
Note that the Sock Shop demo only works on `amd64`.
``` bash
kubectl create namespace sock-shop
kubectl apply -n sock-shop -f "https://github.com/microservices-demo/microservices-demo/blob/master/deploy/kubernetes/complete-demo.yaml?raw=true"
@@ -404,22 +400,14 @@ services](/docs/user-guide/services/) allocated for the front-end service by
running:
``` bash
kubectl describe svc front-end -n sock-shop
kubectl -n sock-shop get svc front-end
```
Output:
```
Name: front-end
Namespace: sock-shop
Labels: name=front-end
Selector: name=front-end
Type: NodePort
IP: 100.66.88.176
Port: <unset> 80/TCP
NodePort: <unset> 31869/TCP
Endpoints: <none>
Session Affinity: None
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
front-end 10.110.250.153 <nodes> 80:30001/TCP 59s
```
It takes several minutes to download and start all the containers, watch the
@@ -428,23 +416,35 @@ running.
Then go to the IP address of your cluster's master node in your browser, and
specify the given port. So for example, `http://<master_ip>:<port>`. In the
example above, this was `30001`, but it is a different port for you.
example above, this was `30001`, but it may be a different port for you.
If there is a firewall, make sure it exposes this port to the internet before
you try to access it.
To uninstall the socks shop, run `kubectl delete namespace sock-shop` on the
master.
## Tear down
* To uninstall the socks shop, run `kubectl delete namespace sock-shop` on the
master.
* To undo what kubeadm did, simply run:
To undo what kubeadm did, you should first [drain the
node](https://kubernetes.io/docs/user-guide/kubectl/kubectl_drain/) and make
sure that the node is empty before shutting it down.
``` bash
kubeadm reset
```
Talking to the master with the appropriate credentials, run:
If you wish to start over, run `systemctl start kubelet` followed by `kubeadm
init` or `kubeadm join`.
``` bash
kubectl drain <node name> --delete-local-data --force --ignore-daemonsets
kubectl delete node <node name>
```
Then, on the node being removed, reset all kubeadm installed state:
``` bash
kubeadm reset
```
If you wish to start over simply run `kubeadm init` or `kubeadm join` with the
appropriate arguments.
## Explore other add-ons
@@ -468,7 +468,7 @@ control of your Kubernetes cluster.
* [GitHub Issues in the kubeadm
repository](https://github.com/kubernetes/kubeadm/issues)
## kubeadm is multi-platform
## kubeadm is multi-platform {#multi-platform}
kubeadm deb packages and binaries are built for amd64, arm and arm64, following
the [multi-platform
@@ -491,9 +491,9 @@ RPi 3 you should set `ARCH` to `arm`, not `arm64`.
## Cloudprovider integrations (experimental)
Enabling specific cloud providers is a common request, this currently requires
manual configuration and is therefore not yet supported. If you wish to do so,
edit the kubeadm dropin for the kubelet service
Enabling specific cloud providers is a common request. This currently requires
manual configuration and is therefore not yet fully supported. If you wish to do
so, edit the kubeadm dropin for the kubelet service
(`/etc/systemd/system/kubelet.service.d/10-kubeadm.conf`) on all nodes,
including the master. If your cloud provider requires any extra packages
installed on host, for example for volume mounting/unmounting, install those
@@ -506,8 +506,17 @@ that file depends on the requirements imposed by your cloud provider. If you use
the `/etc/kubernetes/cloud-config` file, you must append it to the kubelet
arguments as follows: `--cloud-config=/etc/kubernetes/cloud-config`
Lastly, run `kubeadm init --cloud-provider=xxx` to bootstrap your cluster with
cloud provider features.
Next, specify the cloud provider in the kubeadm config file. Create a file called
`kubeadm.conf` with the following contents:
``` yaml
kind: MasterConfiguration
apiVersion: kubeadm.k8s.io/v1alpha1
cloudProvider: <cloud provider>
```
Lastly, run `kubeadm init --config=kubeadm.conf` to bootstrap your cluster with
the cloud provider.
This workflow is not yet fully supported, however we hope to make it extremely
easy to spin up clusters with cloud providers in the future. (See [this
@@ -530,6 +539,7 @@ addressed in due course.
Workaround: regularly [back up
etcd](https://coreos.com/etcd/docs/latest/admin_guide.html). The etcd data
directory configured by kubeadm is at `/var/lib/etcd` on the master.
1. The `HostPort` and `HostIP` functionality does not work with kubeadm due to
that CNI networking is used, see issue
[#31307](https://github.com/kubernetes/kubernetes/issues/31307).
@@ -537,6 +547,7 @@ addressed in due course.
Workaround: use the [NodePort feature of
services](/docs/user-guide/services/#type-nodeport) instead, or use
HostNetwork.
1. Some users on RHEL/CentOS 7 have reported issues with traffic being routed
incorrectly due to iptables being bypassed. You should ensure
`net.bridge.bridge-nf-call-iptables` is set to 1 in your sysctl config, eg.
@@ -552,18 +563,8 @@ addressed in due course.
net.bridge.bridge-nf-call-iptables = 1
```
1. There is no built-in way of fetching the token easily once the cluster is up
and running, but here is a kubectl command you can copy and paste that will
print out the token for you:
``` bash
kubectl -n kube-system get secret clusterinfo -o yaml | \
grep token-map | \
awk '{print $2}' | \
base64 --decode | \
sed "s|{||g;s|}||g;s|:|.|g;s/\"//g;" | \
xargs echo
```
1. Users can list, create and delete tokens using the `kubeadm token` command.
See the [reference guide](/docs/admin/kubeadm/#manage-tokens) for details.
1. If you are using VirtualBox (directly or via Vagrant), you will need to
ensure that `hostname -i` returns a routable IP address (i.e. one on the
@@ -573,3 +574,63 @@ addressed in due course.
[`Vagrantfile`][ubuntu-vagrantfile] for how this can be achieved.
[ubuntu-vagrantfile]: https://github.com/errordeveloper/k8s-playground/blob/22dd39dfc06111235620e6c4404a96ae146f26fd/Vagrantfile#L11),
## Troubleshooting {#troubleshooting}
### Pod Network Troubleshooting {#pod-network-trouble}
You may have trouble in the configuration if you see the following statuses.
This example is for canal but there may be similar errors for other pod network
systems.
```
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system canal-node-f0lqp 2/3 RunContainerError 2 48s
kube-system canal-node-77d0h 2/3 CrashLoopBackOff 3 3m
kube-system kube-dns-2924299975-7q1vq 0/4 ContainerCreating 0 15m
```
The three statuses RunContainerError and CrashLoopBackOff and ContainerCreating
are very common.
To help diagnose what happened, you can use the following command to check what
is in the logs:
``` bash
kubectl describe -n kube-system po {YOUR_POD_NAME}
```
Do not use kubectl logs as they only work with Pods that have started. If you run:
``` bash
kubectl logs -n kube-system canal-node-f0lqp
```
You will got the following error:
```
Error from server (BadRequest): the server rejected our request for an unknown reason (get pods canal-node-f0lqp)
```
The `kubectl describe` comand gives you more details about what went wrong.
``` bash
kubectl describe -n kube-system po kube-dns-2924299975-1l2t7
```
The events should show something like this:
```
2m 2m 1 {kubelet nac} spec.containers{flannel} Warning Failed Failed to start container with docker id 927e7ccdc32b with error: Error response from daemon: {"message":"chown /etc/resolv.conf: operation not permitted"}
```
Or this:
```
6m 1m 191 {kubelet nac} Warning FailedSync Error syncing pod, skipping: failed to "SetupNetwork" for "kube-dns-2924299975-1l2t7_kube-system" with SetupNetworkError: "Failed to setup network for pod \"kube-dns-2924299975-1l2t7_kube-system(dee8ef21-fbcb-11e6-ba19-38d547e0006a)\" using network plugins \"cni\": open /run/flannel/subnet.env: no such file or directory; Skipping pod"
```
A web search on the error message may help narrow down the issue. Or
communicate the errors you are seeing to the community/company that provides the
pod network implementation you are using.
docs/index.md
+1 -1
View File
@@ -19,7 +19,7 @@ title: Kubernetes Documentation
<ul>
<li><a href="/docs/getting-started-guides/minikube/">Minikube</a>: Install a single-node Kubernetes cluster on your local machine for development and testing.</li>
<li><a href="/docs/getting-started-guides/kops/">Installing Kubernetes on AWS with kops</a>: Bring up a complete Kubernetes cluster on Amazon Web Services, using a tool called <code>kops</code>.</li>
<li><a href="/docs/getting-started-guides/kubeadm/">Installing Kubernetes on Linux with kubeadm</a> (Alpha): Install a secure Kubernetes cluster on any pre-existing machines running Linux, using the built-in <code>kubeadm</code> tool.</li>
<li><a href="/docs/getting-started-guides/kubeadm/">Installing Kubernetes on Linux with kubeadm</a> (Beta): Install a secure Kubernetes cluster on any pre-existing machines running Linux, using the built-in <code>kubeadm</code> tool.</li>
<li><a href="/docs/getting-started-guides/kargo/">Installing Kubernetes On-premise/Cloud Providers with Kargo</a>: Deploy a Kubernetes cluster on-premise baremetal or hosted on cloud providers, with Ansible and <code>kargo</code> tools.</li>
</ul>
docs/tools/index.md
+8 -8
View File
@@ -10,23 +10,23 @@ Kubernetes contains several built-in tools to help you work with the Kubernetes
Kubernetes contains the following built-in tools:
##### Kubectl
##### Kubectl
[`kubectl`](/docs/user-guide/kubectl/) is the command line tool for Kubernetes. It controls the Kubernetes cluster manager.
##### Kubeadm
##### Kubeadm
[`kubeadm`](/docs/getting-started-guides/kubeadm/) is the command line tool for easily provisioning a secure Kubernetes cluster on top of physical or cloud servers or virtual machines (currently in alpha).
[`kubeadm`](/docs/getting-started-guides/kubeadm/) is the command line tool for easily provisioning a secure Kubernetes cluster on top of physical or cloud servers or virtual machines (currently in beta).
##### Kubefed
[`kubefed`](/docs/admin/federation/kubefed/) is the command line tool
to help you administrate your federated clusters.
##### Dashboard
##### Dashboard
[Dashboard](/docs/user-guide/ui/), the web-based user interface of Kubernetes, allows you to deploy containerized applications
to a Kubernetes cluster, troubleshoot them, and manage the cluster and its resources itself.
to a Kubernetes cluster, troubleshoot them, and manage the cluster and its resources itself.
#### Third-Party Tools
@@ -37,7 +37,7 @@ Kubernetes supports various third-party tools. These include, but are not limite
[Kubernetes Helm](https://github.com/kubernetes/helm) is a tool for managing packages of pre-configured
Kubernetes resources, aka Kubernetes charts.
Use Helm to:
Use Helm to:
* Find and use popular software packaged as Kubernetes charts
* Share your own applications as Kubernetes charts
@@ -45,10 +45,10 @@ Use Helm to:
* Intelligently manage your Kubernetes manifest files
* Manage releases of Helm packages
##### Kompose
##### Kompose
[Kompose](https://github.com/kubernetes-incubator/kompose) is a tool to help users familiar with Docker Compose
move to Kubernetes.
move to Kubernetes.
Use Kompose to: