docs(tutorials): how to scale vertically

docs/src/SUMMARY.md

@@ -12,7 +12,7 @@
 - [Troubleshooting](./troubleshooting.md)
 - [Tutorials]()
   - [Single node cluster adjustments](./tutorials/single_node_cluster_adjustments.md)
-  - [Add or remove nodes (scale up or down)]()
+  - [Add or remove nodes (scale up or down)](./tutorials/add-or-remove-nodes.md)
   - [Install new applications]()
 - [Reference](./reference/README.md)
   - [Architecture](./reference/architecture.md)

docs/src/tutorials/add-or-remove-nodes.md

@@ -0,0 +1,68 @@
+# Add or remove nodes
+
+Or how to scale vertically. To replace the same node with a clean OS, remove it and add it again.
+
+## Add new nodes
+
+> You can add multiple nodes at the same time
+
+Ensure that it meets the requirements in [prerequisites](../deployment/prerequisites.md), then add its details to the inventory:
+
+```diff
+diff --git a/metal/inventories/prod.yml b/metal/inventories/prod.yml
+index 7f6474a..1bb2cbc 100644
+--- a/metal/inventories/prod.yml
++++ b/metal/inventories/prod.yml
+@@ -8,3 +8,4 @@ metal:
+     workers:
+       hosts:
+         metal3: {ansible_host: 192.168.1.113, mac: '00:23:24:d1:f5:69', disk: sda, network_interface: eno1}
++        metal4: {ansible_host: 192.168.1.114, mac: '00:11:22:33:44:55', disk: sda, network_interface: eno1}
+```
+
+Install the OS and join the cluster:
+
+```
+make metal
+```
+
+That's it!
+
+## Remove a node
+
+> It is recommended to remove nodes one at a time
+
+Remove it from the inventory:
+
+```diff
+diff --git a/metal/inventories/prod.yml b/metal/inventories/prod.yml
+index 7f6474a..d12b50a 100644
+--- a/metal/inventories/prod.yml
++++ b/metal/inventories/prod.yml
+@@ -4,7 +4,6 @@ metal:
+       hosts:
+         metal0: {ansible_host: 192.168.1.110, mac: '00:23:24:d1:f3:f0', disk: sda, network_interface: eno1}
+         metal1: {ansible_host: 192.168.1.111, mac: '00:23:24:d1:f4:d6', disk: sda, network_interface: eno1}
+-        metal2: {ansible_host: 192.168.1.112, mac: '00:23:24:e7:04:60', disk: sda, network_interface: eno1}
+     workers:
+       hosts:
+         metal3: {ansible_host: 192.168.1.113, mac: '00:23:24:d1:f5:69', disk: sda, network_interface: eno1}
+```
+
+Drain the node:
+
+```sh
+kubectl drain ${NODE_NAME} --delete-emptydir-data --ignore-daemonsets --force
+```
+
+Remove the node from the cluster
+
+```sh
+kubectl delete node ${NODE_NAME}
+```
+
+Shutdown the node:
+
+```
+ssh root@${NODE_IP} poweroff
+```