183 lines
6.2 KiB
Markdown
183 lines
6.2 KiB
Markdown
# Adding/replacing a node
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Modified from [comments in #3471](https://github.com/kubernetes-sigs/kubespray/issues/3471#issuecomment-530036084)
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## Limitation: Removal of first kube_control_plane and etcd-master
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Currently you can't remove the first node in your kube_control_plane and etcd-master list. If you still want to remove this node you have to:
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### 1) Change order of current control planes
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Modify the order of your control plane list by pushing your first entry to any other position. E.g. if you want to remove `node-1` of the following example:
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```yaml
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children:
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kube_control_plane:
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hosts:
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node-1:
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node-2:
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node-3:
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kube_node:
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hosts:
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node-1:
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node-2:
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node-3:
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etcd:
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hosts:
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node-1:
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node-2:
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node-3:
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```
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change your inventory to:
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```yaml
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children:
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kube_control_plane:
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hosts:
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node-2:
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node-3:
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node-1:
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kube_node:
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hosts:
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node-2:
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node-3:
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node-1:
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etcd:
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hosts:
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node-2:
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node-3:
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node-1:
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```
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## 2) Upgrade the cluster
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run `upgrade-cluster.yml` or `cluster.yml`. Now you are good to go on with the removal.
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## Adding/replacing a worker node
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This should be the easiest.
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### 1) Add new node to the inventory
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### 2) Run `scale.yml`
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You can use `--limit=NODE_NAME` to limit Kubespray to avoid disturbing other nodes in the cluster.
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Before using `--limit` run playbook `facts.yml` without the limit to refresh facts cache for all nodes.
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### 3) Remove an old node with remove-node.yml
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With the old node still in the inventory, run `remove-node.yml`. You need to pass `-e node=NODE_NAME` to the playbook to limit the execution to the node being removed.
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If the node you want to remove is not online, you should add `reset_nodes=false` and `allow_ungraceful_removal=true` to your extra-vars: `-e node=NODE_NAME -e reset_nodes=false -e allow_ungraceful_removal=true`.
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Use this flag even when you remove other types of nodes like a control plane or etcd nodes.
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### 4) Remove the node from the inventory
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That's it.
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## Adding/replacing a control plane node
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### 1) Run `cluster.yml`
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Append the new host to the inventory and run `cluster.yml`. You can NOT use `scale.yml` for that.
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### 2) Restart kube-system/nginx-proxy
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In all hosts, restart nginx-proxy pod. This pod is a local proxy for the apiserver. Kubespray will update its static config, but it needs to be restarted in order to reload.
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```sh
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# run in every host
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docker ps | grep k8s_nginx-proxy_nginx-proxy | awk '{print $1}' | xargs docker restart
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```
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### 3) Remove old control plane nodes
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With the old node still in the inventory, run `remove-node.yml`. You need to pass `-e node=NODE_NAME` to the playbook to limit the execution to the node being removed.
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If the node you want to remove is not online, you should add `reset_nodes=false` and `allow_ungraceful_removal=true` to your extra-vars.
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## Replacing a first control plane node
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### 1) Change control plane nodes order in inventory
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from
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```ini
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[kube_control_plane]
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node-1
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node-2
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node-3
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```
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to
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```ini
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[kube_control_plane]
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node-2
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node-3
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node-1
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```
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### 2) Remove old first control plane node from cluster
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With the old node still in the inventory, run `remove-node.yml`. You need to pass `-e node=node-1` to the playbook to limit the execution to the node being removed.
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If the node you want to remove is not online, you should add `reset_nodes=false` and `allow_ungraceful_removal=true` to your extra-vars.
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### 3) Edit cluster-info configmap in kube-public namespace
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`kubectl edit cm -n kube-public cluster-info`
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Change ip of old kube_control_plane node with ip of live kube_control_plane node (`server` field). Also, update `certificate-authority-data` field if you changed certs.
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### 4) Add new control plane node
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Update inventory (if needed)
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Run `cluster.yml` with `--limit=kube_control_plane`
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## Adding an etcd node
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You need to make sure there are always an odd number of etcd nodes in the cluster. In such a way, this is always a replace or scale up operation. Either add two new nodes or remove an old one.
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### 1) Add the new node running cluster.yml
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Update the inventory and run `cluster.yml` passing `--limit=etcd,kube_control_plane -e ignore_assert_errors=yes`.
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If the node you want to add as an etcd node is already a worker or control plane node in your cluster, you have to remove him first using `remove-node.yml`.
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Run `upgrade-cluster.yml` also passing `--limit=etcd,kube_control_plane -e ignore_assert_errors=yes`. This is necessary to update all etcd configuration in the cluster.
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At this point, you will have an even number of nodes.
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Everything should still be working, and you should only have problems if the cluster decides to elect a new etcd leader before you remove a node.
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Even so, running applications should continue to be available.
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If you add multiple etcd nodes with one run, you might want to append `-e etcd_retries=10` to increase the amount of retries between each etcd node join.
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Otherwise the etcd cluster might still be processing the first join and fail on subsequent nodes. `etcd_retries=10` might work to join 3 new nodes.
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### 2) Add the new node to apiserver config
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In every control plane node, edit `/etc/kubernetes/manifests/kube-apiserver.yaml`. Make sure the new etcd nodes are present in the apiserver command line parameter `--etcd-servers=...`.
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## Removing an etcd node
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### 1) Remove an old etcd node
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With the node still in the inventory, run `remove-node.yml` passing `-e node=NODE_NAME` as the name of the node that should be removed.
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If the node you want to remove is not online, you should add `reset_nodes=false` and `allow_ungraceful_removal=true` to your extra-vars.
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### 2) Make sure only remaining nodes are in your inventory
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Remove `NODE_NAME` from your inventory file.
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### 3) Update kubernetes and network configuration files with the valid list of etcd members
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Run `cluster.yml` to regenerate the configuration files on all remaining nodes.
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### 4) Remove the old etcd node from apiserver config
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In every control plane node, edit `/etc/kubernetes/manifests/kube-apiserver.yaml`. Make sure only active etcd nodes are still present in the apiserver command line parameter `--etcd-servers=...`.
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### 5) Shutdown the old instance
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That's it.
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