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Update docs/admin/kubeadm.md for 1.8 (#5440)

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- Made a couple of minor wording changes (not strictly 1.8 related).
 - Did some reformatting (not strictly 1.8 related).
 - Updated references to the default token TTL (was infinite, now 24 hours).
 - Documented the new `--discovery-token-ca-cert-hash` and `--discovery-token-unsafe-skip-ca-verification` flags for `kubeadm join`.
 - Added references to the new `--discovery-token-ca-cert-hash` flag in all the default examples.
 - Added a new _Security model_ section that describes the security tradeoffs of the various discovery modes.
 - Documented the new `--groups` flag for `kubeadm token create`.
 - Added a note of caution under _Automating kubeadm_ that references the _Security model_ section.
 - Updated the component version table to drop 1.6 and add 1.8.
 - Update `_data/reference.yml` to try to get the sidebar fixed up and more consistent with `kubefed`.
This commit is contained in:
Matt Moyer
2017-09-13 16:06:26 -05:00
committed by Steve Perry
parent a30edd4c00
commit 3810cb23cb
2 changed files with 303 additions and 160 deletions
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@@ -65,10 +65,8 @@ toc:
- title: Setup Tools - title: Setup Tools
section: section:
- title: Kubeadm - docs/admin/kubeadm.md
path: /docs/admin/kubeadm/
- title: Kubefed - title: Kubefed
path: /docs/admin/kubefed/
section: section:
- docs/admin/kubefed.md - docs/admin/kubefed.md
- docs/admin/kubefed_options.md - docs/admin/kubefed_options.md
docs/admin/kubeadm.md
+302 -157
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@@ -4,11 +4,16 @@ approvers:
- luxas - luxas
- errordeveloper - errordeveloper
- jbeda - jbeda
title: kubeadm Setup Tool Reference Guide title: Kubeadm
notitle: true
--- ---
# kubeadm Setup Tool Reference Guide
This document provides information on how to use kubeadm's advanced options. This document provides information on how to use kubeadm's advanced options.
* TOC
{:toc}
Running `kubeadm init` bootstraps a Kubernetes cluster. This consists of the Running `kubeadm init` bootstraps a Kubernetes cluster. This consists of the
following steps: following steps:
@@ -27,8 +32,9 @@ following steps:
dropping it in the cert directory (configured via `--cert-dir`, by default dropping it in the cert directory (configured via `--cert-dir`, by default
`/etc/kubernetes/pki`), this step is skipped. `/etc/kubernetes/pki`), this step is skipped.
1. Outputting a kubeconfig file for the kubelet to use to connect to the API 1. kubeadm outputs a kubeconfig file for the master's kubelet to use to connect
server, as well as an additional kubeconfig file for administration. to the API server, as well as an additional kubeconfig file for cluster
administrators.
1. kubeadm generates Kubernetes static Pod manifests for the API server, 1. kubeadm generates Kubernetes static Pod manifests for the API server,
controller manager and scheduler. It places them in controller manager and scheduler. It places them in
@@ -46,8 +52,9 @@ following steps:
Running `kubeadm join` on each node in the cluster consists of the following Running `kubeadm join` on each node in the cluster consists of the following
steps: steps:
1. kubeadm downloads root CA information from the API server. It uses the token 1. kubeadm downloads root CA information from the API server. By default, it
to verify the authenticity of that data. uses the bootstrap token and the CA key hash to verify the authenticity of
that data. The root CA can also be discovered directly via a file or URL.
1. kubeadm creates a local key pair. It prepares a certificate signing request 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 (CSR) and sends that off to the API server for signing. The bootstrap token
@@ -72,121 +79,123 @@ 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 cases you might like to override the default behaviour. Here we specify all the
flags that can be used to customise the Kubernetes installation. flags that can be used to customise the Kubernetes installation.
**Options for `kubeadm init`:**
- `--apiserver-advertise-address` - `--apiserver-advertise-address`
This is the address the API Server will advertise to other members of the 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 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 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. IP for the default interface will be used.
This address is also added to the certificate that the API Server uses. This address is also added to the certificate that the API Server uses.
- `--apiserver-bind-port` - `--apiserver-bind-port`
The port that the API server will bind on. This defaults to 6443. The port that the API server will bind on. This defaults to 6443.
- `--apiserver-cert-extra-sans` - `--apiserver-cert-extra-sans`
Additional hostnames or IP addresses that should be added to the Subject 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 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 expose the API Server through a load balancer and public DNS you could specify
this with this with
``` ```
--apiserver-cert-extra-sans=kubernetes.example.com,kube.example.com,10.100.245.1 --apiserver-cert-extra-sans=kubernetes.example.com,kube.example.com,10.100.245.1
``` ```
- `--cert-dir` - `--cert-dir`
The path where to save and store the certificates. The default is The path where to save and store the certificates. The default is
"/etc/kubernetes/pki". "/etc/kubernetes/pki".
- `--config` - `--config`
A kubeadm specific [config file](#config-file). This can be used to specify an 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 extended set of options including passing arbitrary command line flags to the
control plane components. control plane components.
**Note**: When providing configuration values using _both_ a configuration file **Note**: When providing configuration values using _both_ a configuration file
and flags, the file will take precedence. For example, if a file exists with: and flags, the file will take precedence. For example, if a file exists with:
```yaml ```yaml
apiVersion: kubeadm.k8s.io/v1alpha1 apiVersion: kubeadm.k8s.io/v1alpha1
kind: MasterConfiguration kind: MasterConfiguration
token: 1234 token: 1234
``` ```
and the user ran `kubeadm init --config file.yaml --token 5678`, and the user ran `kubeadm init --config file.yaml --token 5678`,
the chosen token value will be `1234`. the chosen token value will be `1234`.
- `--kubernetes-version` (default 'latest') the kubernetes version to initialise - `--kubernetes-version` (default 'latest') the kubernetes version to initialise
The **v1.6** version of kubeadm only supports building clusters that are at 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 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 RBAC, the Bootstrap Token system, and enhancements to the Certificates API. With
this flag you can try any future version of Kubernetes. Check [releases this flag you can try any future version of Kubernetes. Check [releases
page](https://github.com/kubernetes/kubernetes/releases) for a full list of page](https://github.com/kubernetes/kubernetes/releases) for a full list of
available versions. available versions.
- `--pod-network-cidr` - `--pod-network-cidr`
For certain networking solutions the Kubernetes master can also play a role in For certain networking solutions the Kubernetes master can also play a role in
allocating network ranges (CIDRs) to each node. This includes many cloud 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 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 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 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 node in the cluster. If you are using flannel with [this
manifest](https://github.com/coreos/flannel/blob/master/Documentation/kube-flannel.yml) 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 you should use `--pod-network-cidr=10.244.0.0/16`. Most CNI based networking
solutions do not require this flag. solutions do not require this flag.
- `--service-cidr` (default '10.96.0.0/12') - `--service-cidr` (default '10.96.0.0/12')
You can use the `--service-cidr` flag to override the subnet Kubernetes uses to 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 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 `/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file to reflect this
change else DNS will not function correctly. change else DNS will not function correctly.
- `--service-dns-domain` (default 'cluster.local') - `--service-dns-domain` (default 'cluster.local')
By default, `kubeadm init` deploys a cluster that assigns services with DNS By default, `kubeadm init` deploys a cluster that assigns services with DNS
names `<service_name>.<namespace>.svc.cluster.local`. You can use the 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 `--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 update the `/etc/systemd/system/kubelet.service.d/10-kubeadm.conf` file
accordingly else DNS will not function correctly. accordingly else DNS will not function correctly.
**Note**: This flag has an effect (it's needed for the kube-dns Deployment **Note**: This flag has an effect (it's needed for the kube-dns Deployment
manifest and the API Server's serving certificate) but not as you might expect, manifest and the API Server's serving certificate) but not as you might expect,
since you will have to modify the arguments to the kubelets in the cluster for since you will have to modify the arguments to the kubelets in the cluster for
it to work fully. Specifying DNS parameters using this flag only is not enough. it to work fully. Specifying DNS parameters using this flag only is not enough.
Rewriting the kubelet's CLI arguments is out of scope for kubeadm as it should Rewriting the kubelet's CLI arguments is out of scope for kubeadm as it should
be agnostic to how you run the kubelet. However, making all kubelets in the be agnostic to how you run the kubelet. However, making all kubelets in the
cluster pick up information dynamically via the API _is_ in scope and is a cluster pick up information dynamically via the API _is_ in scope and is a
[planned feature](https://github.com/kubernetes/kubeadm/issues/28) for upcoming [planned feature](https://github.com/kubernetes/kubeadm/issues/28) for upcoming
releases. releases.
- `--skip-preflight-checks` - `--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 before making any changes. Advanced users can use this flag to bypass these if
necessary. necessary.
- `--token` - `--token`
By default, `kubeadm init` automatically generates the token used to initialise 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 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 `[a-z0-9]{6}\.[a-z0-9]{16}`. A `--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 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 be managed through the API after the cluster is created. See the [section on
managing tokens](#manage-tokens) below. managing tokens](#manage-tokens) below.
- `--token-ttl` - `--token-ttl`
This sets an expiration time for the token. This is specified as a duration 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 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 will be removed. A value of 0 specifies that the token never expires. The
default. See the [section on managing tokens](#manage-tokens) below. default is 24 hours. See the [section on managing tokens](#manage-tokens) below.
### `kubeadm join` ### `kubeadm join`
@@ -194,15 +203,24 @@ When joining a kubeadm initialized cluster, we need to establish bidirectional
trust. This is split into discovery (having the Node trust the Kubernetes trust. This is split into discovery (having the Node trust the Kubernetes
master) and TLS bootstrap (having the Kubernetes master trust the Node). 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 There are two main schemes for discovery:
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 - **Using a shared token** along with the IP address of the API server and a
via an HTTPS URL. The forms are `kubeadm join --discovery-token hash of the root CA key:
abcdef.1234567890abcdef 1.2.3.4:6443`, `kubeadm join --discovery-file
path/to/file.conf` or `kubeadm join --discovery-file https://url/file.conf`. `kubeadm join --discovery-token abcdef.1234567890abcdef --discovery-token-ca-cert-hash sha256:1234..cdef 1.2.3.4:6443`
- **Using a file** (a subset of the standard kubeconfig file). This file can
be a local file or downloaded via an HTTPS URL:
`kubeadm join --discovery-file path/to/file.conf`
`kubeadm join --discovery-file https://url/file.conf`
Only one form can be used. If the discovery information is loaded from a URL, 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 HTTPS must be used and the host installed CA bundle is used to verify the
connection. connection. For details on the security tradeoffs of these mechanisms, see the
[security model](#security-model) section below.
The TLS bootstrap mechanism is also driven via a shared token. This is used to 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 temporarily authenticate with the Kubernetes master to submit a certificate
@@ -216,60 +234,83 @@ can be used instead of specifying the each token individually.
Here's an example on how to use it: Here's an example on how to use it:
`kubeadm join --token=abcdef.1234567890abcdef 192.168.1.1:6443` `kubeadm join --token=abcdef.1234567890abcdef --discovery-token-ca-cert-hash sha256:1234..cdef 192.168.1.1:6443`
Specific options: **Options for `kubeadm join`:**
- `--config` - `--config`
Extended options a specified in the [kubeadm specific config file](#config-file). Extended options are specified in the [kubeadm specific config file](#config-file).
- `--skip-preflight-checks` - `--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 before making any changes. Advanced users can use this flag to bypass these if
necessary. necessary.
- `--discovery-file` - `--discovery-file`
A local file path or HTTPS URL. The file specified must be a kubeconfig 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 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 location of the API server to join along with a root CA bundle to use when
talking to that server. talking to that server.
This might look something like this: This might look something like this:
``` yaml ``` yaml
apiVersion: v1 apiVersion: v1
clusters: clusters:
- cluster: - cluster:
certificate-authority-data: <really long certificate data> certificate-authority-data: <really long certificate data>
server: https://10.138.0.2:6443 server: https://10.138.0.2:6443
name: "" name: ""
contexts: [] contexts: []
current-context: "" current-context: ""
kind: Config kind: Config
preferences: {} preferences: {}
users: [] users: []
``` ```
- `--discovery-token` - `--discovery-token`
The discovery token is used along with the address of the API server (as an 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 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 most critical part of the cluster information is the root CA bundle used to
verify the identity of the server during subsequent TLS connections. verify the identity of the server during subsequent TLS connections.
- `--discovery-token-ca-cert-hash`
The CA key hash is used to verify the full root CA certificate discovered during
token-based bootstrapping. It has the format `sha256:<hex_encoded_hash>`. By
default, the hash value is returned in the `kubeadm join` command printed at the
end of `kubeadm init`. It is in a standard format (see
[RFC7469](https://tools.ietf.org/html/rfc7469#section-2.4)) and can also be
calculated by 3rd party tools or provisioning systems. For example, using the
OpenSSL CLI:
`openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>&/dev/null | openssl dgst -sha256 -hex`
_Skipping this flag is allowed in Kubernetes 1.8, but makes certain spoofing
attacks possible._ See the [security model](#security-model) for details.
Pass `--discovery-token-unsafe-skip-ca-verification` to silence warnings (which
will become errors in Kubernetes 1.9).
- `--discovery-token-unsafe-skip-ca-verification`
Disable the warning/error that occurs when `--discovery-token-ca-cert-hash` is
not provided. Passing this flag is an acknowledgement of the
[security tradeoffs](#security-model) involved in skipping this verification
(which may or may not be appropriate in your environment).
- `--tls-bootstrap-token` - `--tls-bootstrap-token`
The token used to authenticate to the API server for the purposes of TLS The token used to authenticate to the API server for the purposes of TLS
bootstrapping. bootstrapping.
- `--token=<token>` - `--token=<token>`
Often times the same token is used for both `--discovery-token` and Often times the same token is used for both `--discovery-token` and
`--tls-bootstrap-token`. This option specifies the same token for both. Other `--tls-bootstrap-token`. This option specifies the same token for both. Other
flags override this flag if present. flags override this flag if present.
## Using kubeadm with a configuration file {#config-file} ## Using kubeadm with a configuration file {#config-file}
@@ -414,34 +455,53 @@ created cluster (`/etc/kubernetes/admin.conf`). You can specify an alternate
kubeconfig file for credentials with the `--kubeconfig` to the following kubeconfig file for credentials with the `--kubeconfig` to the following
commands. commands.
* `kubeadm token list` Lists the tokens along with when they expire and what the * `kubeadm token list` - List tokens (along with their expirations, usages, and groups).
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. The unit of the duration is seconds.
* `--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 * `kubeadm token create` - Create a new token.
a new token. This token is of the correct form for specifying with the
`--token` argument to `kubeadm init`. * `--description <description>`
Set the human-readable description for the new token.
* `--ttl <duration>`
Set the expiration time-to-live of the token relative to the current time.
Default is 24 hours. A value of 0 means "never expire". The default unit
of the duration is seconds but other units can be specified (e.g., `15m`, `1h`).
* `--usages <usage>[,<usage>...]`
Set the ways that the token can be used. The default is
`signing,authentication`. These are the usages as described above.
* `--groups <group>[,<group>...]`
Add extra bootstrap groups that the new token will authenticate as. Can be
specified multiple times. Each extra group must start with
`system:bootstrappers:`. This is an advanced feature meant for custom
bootstrap scenarios where you want to change how CSR approval works for
different groups of nodes.
* `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.
* `kubeadm token generate` - Generate a token locally.
Locally generate a token but do not create it on the server. 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 For the gory details on how the tokens are implemented (including managing them
outside of kubeadm) see the [Bootstrap Token outside of kubeadm) see the [Bootstrap Token docs](/docs/admin/bootstrap-tokens/).
docs](/docs/admin/bootstrap-tokens/).
## Automating kubeadm ## Automating kubeadm
Rather than copying the token you obtained from `kubeadm init` to each node, as Rather than copying the token you obtained from `kubeadm init` to each node, as
in the [basic kubeadm tutorial](/docs/admin/kubeadm/), you can in the [basic kubeadm tutorial](/docs/admin/kubeadm/), you can parallelize the
parallelize the token distribution for easier automation. To implement this token distribution for easier automation. To implement this automation, you must
automation, you must know the IP address that the master will have after it is know the IP address that the master will have after it is started.
started.
1. Generate a token. This token must have the form `<6 character string>.<16 1. Generate a token. This token must have the form `<6 character string>.<16
character string>`. More formally, it must match the regex: character string>`. More formally, it must match the regex:
@@ -460,6 +520,91 @@ started.
Once the cluster is up, you can grab the admin credentials from the master node 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. at `/etc/kubernetes/admin.conf` and use that to talk to the cluster.
Note that this style of bootstrap has some relaxed security guarantees because
it does not allow the root CA hash to be validated with
`--discovery-token-ca-cert-hash` (since it's not generated when the nodes are
provisioned). For details, see the [security model](#security-model).
## Security model
The kubeadm discovery system has several options, each with security tradeoffs.
The right method for your environment depends on how you provision nodes and the
security expectations you have about your network and node lifecycles.
### Token-based discovery with CA pinning
_This is the default mode in Kubernetes 1.8._ In this mode, kubeadm downloads
the cluster configuration (including root CA) and validates it using the token
as well as validating that the root CA public key matches the provided hash and
that the API server certificate is valid under the root CA.
**Example `kubeadm join` command:**
- `kubeadm join --discovery-token abcdef.1234567890abcdef --discovery-token-ca-cert-hash sha256:1234..cdef 1.2.3.4:6443`
**Advantages:**
- Allows bootstrapping nodes to securely discover a root of trust for the
master even if other worker nodes or the network are compromised.
- Convenient to execute manually since all of the information required fits
into a single `kubeadm join` command that is easy to copy and paste.
**Disadvantages:**
- The CA hash is not normally known until the master has been provisioned,
which can make it more difficult to build automated provisioning tools that
use kubeadm.
### Token-based discovery without CA pinning
_This was the default in Kubernetes 1.7 and earlier_, but comes with some
important caveats. This mode relies only on the symmetric token to sign
(HMAC-SHA256) the discovery information that establishes the root of trust for
the master. It's still possible in Kubernetes 1.8 and above using the
`--discovery-token-unsafe-skip-ca-verification` flag, but you should consider
using one of the other modes if possible.
**Example `kubeadm join` command:**
- `kubeadm join --discovery-token abcdef.1234567890abcdef --discovery-token-unsafe-skip-ca-verification 1.2.3.4:6443`
**Advantages:**
- Still protects against many network-level attacks.
- The token can be generated ahead of time and shared with the master and
worker nodes, which can then bootstrap in parallel without coordination. This
allows it to be used in many provisioning scenarios.
**Disadvantages:**
- If an attacker is able to steal a bootstrap token via some vulnerability,
they can use that token (along with network-level access) to impersonate the
master to other bootstrapping nodes. This may or may not be an appropriate
tradeoff in your environment.
### File or HTTPS-based discovery
This provides an out-of-band way to establish a root of trust between the master
and bootstrapping nodes. Consider using this mode if you are building automated provisioning
using kubeadm.
**Example `kubeadm join` commands:**
- `kubeadm join --discovery-file path/to/file.conf` (local file)
- `kubeadm join --discovery-file https://url/file.conf` (remote HTTPS URL)
**Advantages:**
- Allows bootstrapping nodes to securely discover a root of trust for the
master even if other worker nodes or the network are compromised.
**Disadvantages:**
- Requires that you have some way to carry the discovery information from
the master to the bootstrapping nodes. This might be possible, for example,
via your cloud provider or provisioning tool. The information in this file is
not secret, but HTTPS or equivalent is required to ensure its integrity.
- Less convenient to use manually since the file is difficult to copy and paste
between nodes.
## Use Kubeadm with other CRI runtimes ## Use Kubeadm with other CRI runtimes
Since [Kubernetes 1.6 release](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.md#node-components-1), Kubernetes container runtimes have been transferred to using CRI by default. Currently, the build-in container runtime is Docker which is enabled by build-in `dockershim` in `kubelet`. Since [Kubernetes 1.6 release](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.md#node-components-1), Kubernetes container runtimes have been transferred to using CRI by default. Currently, the build-in container runtime is Docker which is enabled by build-in `dockershim` in `kubelet`.
@@ -492,17 +637,17 @@ the following images are required for the cluster works will be automatically
pulled by the kubelet if they don't exist locally while `kubeadm init` is initializing pulled by the kubelet if they don't exist locally while `kubeadm init` is initializing
your master: your master:
| Image Name | v1.6 release branch version | v1.7 release branch version | Image Name | v1.7 release branch version | v1.8 release branch version
|---|---|---| |---|---|---|
| gcr.io/google_containers/kube-apiserver-${ARCH} | v1.6.x | v1.7.x | gcr.io/google_containers/kube-apiserver-${ARCH} | v1.7.x | v1.8.x
| gcr.io/google_containers/kube-controller-manager-${ARCH} | v1.6.x | v1.7.x | gcr.io/google_containers/kube-controller-manager-${ARCH} | v1.7.x | v1.8.x
| gcr.io/google_containers/kube-scheduler-${ARCH} | v1.6.x | v1.7.x | gcr.io/google_containers/kube-scheduler-${ARCH} | v1.7.x | v1.8.x
| gcr.io/google_containers/kube-proxy-${ARCH} | v1.6.x | v1.7.x | gcr.io/google_containers/kube-proxy-${ARCH} | v1.7.x | v1.8.x
| gcr.io/google_containers/etcd-${ARCH} | 3.0.17 | 3.0.17 | gcr.io/google_containers/etcd-${ARCH} | 3.0.17 | 3.0.17
| gcr.io/google_containers/pause-${ARCH} | 3.0 | 3.0 | gcr.io/google_containers/pause-${ARCH} | 3.0 | 3.0
| gcr.io/google_containers/k8s-dns-sidecar-${ARCH} | 1.14.1 | 1.14.4 | gcr.io/google_containers/k8s-dns-sidecar-${ARCH} | 1.14.4 | 1.14.4
| gcr.io/google_containers/k8s-dns-kube-dns-${ARCH} | 1.14.1 | 1.14.4 | gcr.io/google_containers/k8s-dns-kube-dns-${ARCH} | 1.14.4 | 1.14.4
| gcr.io/google_containers/k8s-dns-dnsmasq-nanny-${ARCH} | 1.14.1 | 1.14.4 | gcr.io/google_containers/k8s-dns-dnsmasq-nanny-${ARCH} | 1.14.4 | 1.14.4
Here `v1.7.x` means the "latest patch release of the v1.7 branch". Here `v1.7.x` means the "latest patch release of the v1.7 branch".
@@ -534,7 +679,7 @@ A breakdown of what/why:
tells the kubelet where the API server is. This file also has the kubelet's tells the kubelet where the API server is. This file also has the kubelet's
credentials. credentials.
* `--require-kubeconfig=true` the kubelet should fail fast if the kubeconfig file * `--require-kubeconfig=true` the kubelet should fail fast if the kubeconfig file
is not present. This makes the kubelet crashloop during the time the service is is not present. This makes the kubelet crash loop during the time the service is
started until `kubeadm init` is run. started until `kubeadm init` is run.
* `--pod-manifest-path=/etc/kubernetes/manifests` specifies from where to read * `--pod-manifest-path=/etc/kubernetes/manifests` specifies from where to read
Static Pod manifests used for spinning up the control plane Static Pod manifests used for spinning up the control plane
@@ -562,7 +707,7 @@ A breakdown of what/why:
systemctl restart kubelet systemctl restart kubelet
``` ```
## Cloudprovider integrations (experimental) ## Cloud provider integrations (experimental)
Enabling specific cloud providers is a common request. This currently requires 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 manual configuration and is therefore not yet fully supported. If you wish to do
@@ -573,7 +718,7 @@ installed on the host, for example for volume mounting/unmounting, install those
packages. packages.
Specify the `--cloud-provider` flag for the kubelet and set it to the cloud of your Specify the `--cloud-provider` flag for the kubelet and set it to the cloud of your
choice. If your cloudprovider requires a configuration file, create the file choice. If your cloud provider requires a configuration file, create the file
`/etc/kubernetes/cloud-config` on every node. The exact format and content of `/etc/kubernetes/cloud-config` on every node. The exact format and content of
that file depends on the requirements imposed by your cloud provider. If you use 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 the `/etc/kubernetes/cloud-config` file, you must append it to the kubelet