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Fix Markdown formatting

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This commit is contained in:
Tim Bannister
2022-01-17 21:38:22 +00:00
parent 62905feb8e
commit 000536e52c
1 changed files with 213 additions and 209 deletions
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content/en/docs/setup/production-environment/tools/kubeadm/high-availability.md
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@@ -12,9 +12,9 @@ This page explains two different approaches to setting up a highly available Kub
cluster using kubeadm:
- With stacked control plane nodes. This approach requires less infrastructure. The etcd members
and control plane nodes are co-located.
and control plane nodes are co-located.
- With an external etcd cluster. This approach requires more infrastructure. The
control plane nodes and etcd members are separated.
control plane nodes and etcd members are separated.
Before proceeding, you should carefully consider which approach best meets the needs of your applications
and environment. [This comparison topic](/docs/setup/production-environment/tools/kubeadm/ha-topology/) outlines the advantages and disadvantages of each.
@@ -60,147 +60,146 @@ There are many configurations for load balancers. The following example is only
option. Your cluster requirements may need a different configuration.
{{< /note >}}
1. Create a kube-apiserver load balancer with a name that resolves to DNS.
1. Create a kube-apiserver load balancer with a name that resolves to DNS.
- In a cloud environment you should place your control plane nodes behind a TCP
forwarding load balancer. This load balancer distributes traffic to all
healthy control plane nodes in its target list. The health check for
an apiserver is a TCP check on the port the kube-apiserver listens on
(default value `:6443`).
- In a cloud environment you should place your control plane nodes behind a TCP
forwarding load balancer. This load balancer distributes traffic to all
healthy control plane nodes in its target list. The health check for
an apiserver is a TCP check on the port the kube-apiserver listens on
(default value `:6443`).
- It is not recommended to use an IP address directly in a cloud environment.
- It is not recommended to use an IP address directly in a cloud environment.
- The load balancer must be able to communicate with all control plane nodes
on the apiserver port. It must also allow incoming traffic on its
listening port.
- The load balancer must be able to communicate with all control plane nodes
on the apiserver port. It must also allow incoming traffic on its
listening port.
- Make sure the address of the load balancer always matches
the address of kubeadm's `ControlPlaneEndpoint`.
- Make sure the address of the load balancer always matches
the address of kubeadm's `ControlPlaneEndpoint`.
- Read the [Options for Software Load Balancing](https://git.k8s.io/kubeadm/docs/ha-considerations.md#options-for-software-load-balancing)
guide for more details.
- Read the [Options for Software Load Balancing](https://git.k8s.io/kubeadm/docs/ha-considerations.md#options-for-software-load-balancing)
guide for more details.
1. Add the first control plane nodes to the load balancer and test the
connection:
1. Add the first control plane node to the load balancer, and test the
connection:
```sh
nc -v LOAD_BALANCER_IP PORT
```
```shell
nc -v <LOAD_BALANCER_IP> <PORT>
```
- A connection refused error is expected because the apiserver is not yet
running. A timeout, however, means the load balancer cannot communicate
with the control plane node. If a timeout occurs, reconfigure the load
balancer to communicate with the control plane node.
A connection refused error is expected because the API server is not yet
running. A timeout, however, means the load balancer cannot communicate
with the control plane node. If a timeout occurs, reconfigure the load
balancer to communicate with the control plane node.
1. Add the remaining control plane nodes to the load balancer target group.
1. Add the remaining control plane nodes to the load balancer target group.
## Stacked control plane and etcd nodes
### Steps for the first control plane node
1. Initialize the control plane:
1. Initialize the control plane:
```sh
sudo kubeadm init --control-plane-endpoint "LOAD_BALANCER_DNS:LOAD_BALANCER_PORT" --upload-certs
```
```sh
sudo kubeadm init --control-plane-endpoint "LOAD_BALANCER_DNS:LOAD_BALANCER_PORT" --upload-certs
```
- You can use the `--kubernetes-version` flag to set the Kubernetes version to use.
It is recommended that the versions of kubeadm, kubelet, kubectl and Kubernetes match.
- The `--control-plane-endpoint` flag should be set to the address or DNS and port of the load balancer.
- You can use the `--kubernetes-version` flag to set the Kubernetes version to use.
It is recommended that the versions of kubeadm, kubelet, kubectl and Kubernetes match.
- The `--control-plane-endpoint` flag should be set to the address or DNS and port of the load balancer.
- The `--upload-certs` flag is used to upload the certificates that should be shared
across all the control-plane instances to the cluster. If instead, you prefer to copy certs across
control-plane nodes manually or using automation tools, please remove this flag and refer to [Manual
certificate distribution](#manual-certs) section below.
- The `--upload-certs` flag is used to upload the certificates that should be shared
across all the control-plane instances to the cluster. If instead, you prefer to copy certs across
control-plane nodes manually or using automation tools, please remove this flag and refer to [Manual
certificate distribution](#manual-certs) section below.
{{< note >}}
The `kubeadm init` flags `--config` and `--certificate-key` cannot be mixed, therefore if you want
to use the [kubeadm configuration](/docs/reference/config-api/kubeadm-config.v1beta3/)
you must add the `certificateKey` field in the appropriate config locations
(under `InitConfiguration` and `JoinConfiguration: controlPlane`).
{{< /note >}}
{{< note >}}
The `kubeadm init` flags `--config` and `--certificate-key` cannot be mixed, therefore if you want
to use the [kubeadm configuration](/docs/reference/config-api/kubeadm-config.v1beta3/)
you must add the `certificateKey` field in the appropriate config locations
(under `InitConfiguration` and `JoinConfiguration: controlPlane`).
{{< /note >}}
{{< note >}}
Some CNI network plugins require additional configuration, for example specifying the pod IP CIDR, while others do not.
See the [CNI network documentation](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network).
To add a pod CIDR pass the flag `--pod-network-cidr`, or if you are using a kubeadm configuration file
set the `podSubnet` field under the `networking` object of `ClusterConfiguration`.
{{< /note >}}
{{< note >}}
Some CNI network plugins require additional configuration, for example specifying the pod IP CIDR, while others do not.
See the [CNI network documentation](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network).
To add a pod CIDR pass the flag `--pod-network-cidr`, or if you are using a kubeadm configuration file
set the `podSubnet` field under the `networking` object of `ClusterConfiguration`.
{{< /note >}}
- The output looks similar to:
The output looks similar to:
```sh
...
You can now join any number of control-plane node by running the following command on each as a root:
kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07
```sh
...
You can now join any number of control-plane node by running the following command on each as a root:
kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07
Please note that the certificate-key gives access to cluster sensitive data, keep it secret!
As a safeguard, uploaded-certs will be deleted in two hours; If necessary, you can use kubeadm init phase upload-certs to reload certs afterward.
Please note that the certificate-key gives access to cluster sensitive data, keep it secret!
As a safeguard, uploaded-certs will be deleted in two hours; If necessary, you can use kubeadm init phase upload-certs to reload certs afterward.
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866
```
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866
```
- Copy this output to a text file. You will need it later to join control plane and worker nodes to the cluster.
- When `--upload-certs` is used with `kubeadm init`, the certificates of the primary control plane
are encrypted and uploaded in the `kubeadm-certs` Secret.
- To re-upload the certificates and generate a new decryption key, use the following command on a control plane
node that is already joined to the cluster:
- Copy this output to a text file. You will need it later to join control plane and worker nodes to
the cluster.
- When `--upload-certs` is used with `kubeadm init`, the certificates of the primary control plane
are encrypted and uploaded in the `kubeadm-certs` Secret.
- To re-upload the certificates and generate a new decryption key, use the following command on a
control plane
node that is already joined to the cluster:
```sh
sudo kubeadm init phase upload-certs --upload-certs
```
```sh
sudo kubeadm init phase upload-certs --upload-certs
```
- You can also specify a custom `--certificate-key` during `init` that can later be used by `join`.
To generate such a key you can use the following command:
- You can also specify a custom `--certificate-key` during `init` that can later be used by `join`.
To generate such a key you can use the following command:
```sh
kubeadm certs certificate-key
```
```sh
kubeadm certs certificate-key
```
{{< note >}}
The `kubeadm-certs` Secret and decryption key expire after two hours.
{{< /note >}}
{{< note >}}
The `kubeadm-certs` Secret and decryption key expire after two hours.
{{< /note >}}
{{< caution >}}
As stated in the command output, the certificate key gives access to cluster sensitive data, keep it secret!
{{< /caution >}}
{{< caution >}}
As stated in the command output, the certificate key gives access to cluster sensitive data, keep it secret!
{{< /caution >}}
1. Apply the CNI plugin of your choice:
[Follow these instructions](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network)
to install the CNI provider. Make sure the configuration corresponds to the Pod CIDR specified in the kubeadm configuration file if applicable.
{{< note >}}
You must pick a network plugin that suits your use case and deploy it before you move on to next step.
If you don't do this, you will not be able to launch your cluster properly.
{{< /note >}}
1. Apply the CNI plugin of your choice:
[Follow these instructions](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network)
to install the CNI provider. Make sure the configuration corresponds to the Pod CIDR specified in the
kubeadm configuration file (if applicable).
1. Type the following and watch the pods of the control plane components get started:
{{< note >}}
You must pick a network plugin that suits your use case and deploy it before you move on to next step.
If you don't do this, you will not be able to launch your cluster properly.
{{< /note >}}
```sh
kubectl get pod -n kube-system -w
```
1. Type the following and watch the pods of the control plane components get started:
```sh
kubectl get pod -n kube-system -w
```
### Steps for the rest of the control plane nodes
{{< note >}}
Since kubeadm version 1.15 you can join multiple control-plane nodes in parallel.
Prior to this version, you must join new control plane nodes sequentially, only after
the first node has finished initializing.
{{< /note >}}
For each additional control plane node you should:
1. Execute the join command that was previously given to you by the `kubeadm init` output on the first node.
It should look something like this:
1. Execute the join command that was previously given to you by the `kubeadm init` output on the first node.
It should look something like this:
```sh
sudo kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07
```
```sh
sudo kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07
```
- The `--control-plane` flag tells `kubeadm join` to create a new control plane.
- The `--certificate-key ...` will cause the control plane certificates to be downloaded
from the `kubeadm-certs` Secret in the cluster and be decrypted using the given key.
- The `--control-plane` flag tells `kubeadm join` to create a new control plane.
- The `--certificate-key ...` will cause the control plane certificates to be downloaded
from the `kubeadm-certs` Secret in the cluster and be decrypted using the given key.
You can join multiple control-plane nodes in parallel.
## External etcd nodes
@@ -210,60 +209,64 @@ in the kubeadm config file.
### Set up the etcd cluster
1. Follow [these instructions](/docs/setup/production-environment/tools/kubeadm/setup-ha-etcd-with-kubeadm/) to set up the etcd cluster.
1. Follow these [instructions](/docs/setup/production-environment/tools/kubeadm/setup-ha-etcd-with-kubeadm/) to set up the etcd cluster.
1. Setup SSH as described [here](#manual-certs).
1. Setup SSH as described [here](#manual-certs).
1. Copy the following files from any etcd node in the cluster to the first control plane node:
1. Copy the following files from any etcd node in the cluster to the first control plane node:
```sh
export CONTROL_PLANE="ubuntu@10.0.0.7"
scp /etc/kubernetes/pki/etcd/ca.crt "${CONTROL_PLANE}":
scp /etc/kubernetes/pki/apiserver-etcd-client.crt "${CONTROL_PLANE}":
scp /etc/kubernetes/pki/apiserver-etcd-client.key "${CONTROL_PLANE}":
```
```sh
export CONTROL_PLANE="ubuntu@10.0.0.7"
scp /etc/kubernetes/pki/etcd/ca.crt "${CONTROL_PLANE}":
scp /etc/kubernetes/pki/apiserver-etcd-client.crt "${CONTROL_PLANE}":
scp /etc/kubernetes/pki/apiserver-etcd-client.key "${CONTROL_PLANE}":
```
- Replace the value of `CONTROL_PLANE` with the `user@host` of the first control-plane node.
- Replace the value of `CONTROL_PLANE` with the `user@host` of the first control-plane node.
### Set up the first control plane node
1. Create a file called `kubeadm-config.yaml` with the following contents:
1. Create a file called `kubeadm-config.yaml` with the following contents:
apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: stable
controlPlaneEndpoint: "LOAD_BALANCER_DNS:LOAD_BALANCER_PORT"
etcd:
external:
endpoints:
- https://ETCD_0_IP:2379
- https://ETCD_1_IP:2379
- https://ETCD_2_IP:2379
caFile: /etc/kubernetes/pki/etcd/ca.crt
certFile: /etc/kubernetes/pki/apiserver-etcd-client.crt
keyFile: /etc/kubernetes/pki/apiserver-etcd-client.key
{{< note >}}
The difference between stacked etcd and external etcd here is that the external etcd setup requires
a configuration file with the etcd endpoints under the `external` object for `etcd`.
In the case of the stacked etcd topology this is managed automatically.
{{< /note >}}
```yaml
---
apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: stable
controlPlaneEndpoint: "LOAD_BALANCER_DNS:LOAD_BALANCER_PORT" # change this (see below)
etcd:
external:
endpoints:
- https://ETCD_0_IP:2379 # change ETCD_0_IP appropriately
- https://ETCD_1_IP:2379 # change ETCD_1_IP appropriately
- https://ETCD_2_IP:2379 # change ETCD_2_IP appropriately
caFile: /etc/kubernetes/pki/etcd/ca.crt
certFile: /etc/kubernetes/pki/apiserver-etcd-client.crt
keyFile: /etc/kubernetes/pki/apiserver-etcd-client.key
```
- Replace the following variables in the config template with the appropriate values for your cluster:
{{< note >}}
The difference between stacked etcd and external etcd here is that the external etcd setup requires
a configuration file with the etcd endpoints under the `external` object for `etcd`.
In the case of the stacked etcd topology, this is managed automatically.
{{< /note >}}
- `LOAD_BALANCER_DNS`
- `LOAD_BALANCER_PORT`
- `ETCD_0_IP`
- `ETCD_1_IP`
- `ETCD_2_IP`
- Replace the following variables in the config template with the appropriate values for your cluster:
- `LOAD_BALANCER_DNS`
- `LOAD_BALANCER_PORT`
- `ETCD_0_IP`
- `ETCD_1_IP`
- `ETCD_2_IP`
The following steps are similar to the stacked etcd setup:
1. Run `sudo kubeadm init --config kubeadm-config.yaml --upload-certs` on this node.
1. Run `sudo kubeadm init --config kubeadm-config.yaml --upload-certs` on this node.
1. Write the output join commands that are returned to a text file for later use.
1. Write the output join commands that are returned to a text file for later use.
1. Apply the CNI plugin of your choice.
1. Apply the CNI plugin of your choice.
{{< note >}}
You must pick a network plugin that suits your use case and deploy it before you move on to next step.
@@ -276,7 +279,7 @@ The steps are the same as for the stacked etcd setup:
- Make sure the first control plane node is fully initialized.
- Join each control plane node with the join command you saved to a text file. It's recommended
to join the control plane nodes one at a time.
to join the control plane nodes one at a time.
- Don't forget that the decryption key from `--certificate-key` expires after two hours, by default.
## Common tasks after bootstrapping control plane
@@ -296,79 +299,80 @@ If you choose to not use `kubeadm init` with the `--upload-certs` flag this mean
you are going to have to manually copy the certificates from the primary control plane node to the
joining control plane nodes.
There are many ways to do this. In the following example we are using `ssh` and `scp`:
There are many ways to do this. The following example uses `ssh` and `scp`:
SSH is required if you want to control all nodes from a single machine.
1. Enable ssh-agent on your main device that has access to all other nodes in
the system:
1. Enable ssh-agent on your main device that has access to all other nodes in
the system:
```
eval $(ssh-agent)
```
eval $(ssh-agent)
```
1. Add your SSH identity to the session:
```
ssh-add ~/.ssh/path_to_private_key
```
1. SSH between nodes to check that the connection is working correctly.
- When you SSH to any node, add the `-A` flag. This flag allows the node that you
have logged into via SSH to access the SSH agent on your PC.
```
ssh -A 10.0.0.7
```
- When using sudo on any node, make sure to preserve the environment so SSH
forwarding works:
```
sudo -E -s
```
1. After configuring SSH on all the nodes you should run the following script on the first
control plane node after running `kubeadm init`. This script will copy the certificates from
the first control plane node to the other control plane nodes:
In the following example, replace `CONTROL_PLANE_IPS` with the IP addresses of the
other control plane nodes.
```sh
USER=ubuntu # customizable
CONTROL_PLANE_IPS="10.0.0.7 10.0.0.8"
for host in ${CONTROL_PLANE_IPS}; do
scp /etc/kubernetes/pki/ca.crt "${USER}"@$host:
scp /etc/kubernetes/pki/ca.key "${USER}"@$host:
scp /etc/kubernetes/pki/sa.key "${USER}"@$host:
scp /etc/kubernetes/pki/sa.pub "${USER}"@$host:
scp /etc/kubernetes/pki/front-proxy-ca.crt "${USER}"@$host:
scp /etc/kubernetes/pki/front-proxy-ca.key "${USER}"@$host:
scp /etc/kubernetes/pki/etcd/ca.crt "${USER}"@$host:etcd-ca.crt
# Quote this line if you are using external etcd
scp /etc/kubernetes/pki/etcd/ca.key "${USER}"@$host:etcd-ca.key
done
```
1. Add your SSH identity to the session:
```
ssh-add ~/.ssh/path_to_private_key
```
1. SSH between nodes to check that the connection is working correctly.
- When you SSH to any node, make sure to add the `-A` flag:
```
ssh -A 10.0.0.7
```
- When using sudo on any node, make sure to preserve the environment so SSH
forwarding works:
```
sudo -E -s
```
1. After configuring SSH on all the nodes you should run the following script on the first control plane node after
running `kubeadm init`. This script will copy the certificates from the first control plane node to the other
control plane nodes:
In the following example, replace `CONTROL_PLANE_IPS` with the IP addresses of the
other control plane nodes.
```sh
USER=ubuntu # customizable
CONTROL_PLANE_IPS="10.0.0.7 10.0.0.8"
for host in ${CONTROL_PLANE_IPS}; do
scp /etc/kubernetes/pki/ca.crt "${USER}"@$host:
scp /etc/kubernetes/pki/ca.key "${USER}"@$host:
scp /etc/kubernetes/pki/sa.key "${USER}"@$host:
scp /etc/kubernetes/pki/sa.pub "${USER}"@$host:
scp /etc/kubernetes/pki/front-proxy-ca.crt "${USER}"@$host:
scp /etc/kubernetes/pki/front-proxy-ca.key "${USER}"@$host:
scp /etc/kubernetes/pki/etcd/ca.crt "${USER}"@$host:etcd-ca.crt
# Quote this line if you are using external etcd
scp /etc/kubernetes/pki/etcd/ca.key "${USER}"@$host:etcd-ca.key
done
```
{{< caution >}}
Copy only the certificates in the above list. kubeadm will take care of generating the rest of the certificates
with the required SANs for the joining control-plane instances. If you copy all the certificates by mistake,
the creation of additional nodes could fail due to a lack of required SANs.
{{< /caution >}}
{{< caution >}}
Copy only the certificates in the above list. kubeadm will take care of generating the rest of the certificates
with the required SANs for the joining control-plane instances. If you copy all the certificates by mistake,
the creation of additional nodes could fail due to a lack of required SANs.
{{< /caution >}}
1. Then on each joining control plane node you have to run the following script before running `kubeadm join`.
This script will move the previously copied certificates from the home directory to `/etc/kubernetes/pki`:
```sh
USER=ubuntu # customizable
mkdir -p /etc/kubernetes/pki/etcd
mv /home/${USER}/ca.crt /etc/kubernetes/pki/
mv /home/${USER}/ca.key /etc/kubernetes/pki/
mv /home/${USER}/sa.pub /etc/kubernetes/pki/
mv /home/${USER}/sa.key /etc/kubernetes/pki/
mv /home/${USER}/front-proxy-ca.crt /etc/kubernetes/pki/
mv /home/${USER}/front-proxy-ca.key /etc/kubernetes/pki/
mv /home/${USER}/etcd-ca.crt /etc/kubernetes/pki/etcd/ca.crt
# Quote this line if you are using external etcd
mv /home/${USER}/etcd-ca.key /etc/kubernetes/pki/etcd/ca.key
```
```sh
USER=ubuntu # customizable
mkdir -p /etc/kubernetes/pki/etcd
mv /home/${USER}/ca.crt /etc/kubernetes/pki/
mv /home/${USER}/ca.key /etc/kubernetes/pki/
mv /home/${USER}/sa.pub /etc/kubernetes/pki/
mv /home/${USER}/sa.key /etc/kubernetes/pki/
mv /home/${USER}/front-proxy-ca.crt /etc/kubernetes/pki/
mv /home/${USER}/front-proxy-ca.key /etc/kubernetes/pki/
mv /home/${USER}/etcd-ca.crt /etc/kubernetes/pki/etcd/ca.crt
# Quote this line if you are using external etcd
mv /home/${USER}/etcd-ca.key /etc/kubernetes/pki/etcd/ca.key
```