init k8s guide

content/posts/11-build-your-own-kubernetes-cluster-part-2/index.md

@@ -117,9 +117,7 @@ terraform {
     }
   }
 
-  backend "local" {
-    path = "terraform.tfstate"
-  }
+  backend "local" {}
 }
 
 variable "hcloud_token" {
@@ -228,9 +226,7 @@ Get a complete description of the above file [here](https://github.com/okami101/
 {{< tab tabName="State" >}}
 
 ```tf
-backend "local" {
-  path = "terraform.tfstate"
-}
+backend "local" {}
 ```
 
 I'm using a local backend for simplicity, but for teams sharing, you may use more appropriate backend, like S3 or Terraform Cloud (the most secured with encryption at REST, versioning and centralized locking).

content/posts/12-build-your-own-kubernetes-cluster-part-3/index.md

@@ -12,10 +12,60 @@ Be free from AWS/Azure/GCP by building a production grade On-Premise Kubernetes
 
 This is the **Part III** of more global topic tutorial. [Back to first part]({{< ref "/posts/10-build-your-own-kubernetes-cluster" >}}) for intro.
 
-## Automatic upgrades
+## Kubernetes cluster initialization with Terraform
 
-* OS reboot
-* K3s upgrade
+For this part let's create a new Terraform project that will be dedicated to Kubernetes infrastructure provisioning. Start from scratch with a new empty folder and the following `main.tf` file then `terraform init`.
+
+{{< highlight file="main.tf" >}}
+
+```tf
+terraform {
+  backend "local" {}
+}
+```
+
+{{</ highlight >}}
+
+Let's begin with automatic upgrades management.
+
+### Automatic reboot
+
+When OS kernel is upgraded, the system needs to be rebooted to apply it. This is a critical operation for a Kubernetes cluster as can cause downtime. To avoid this, we'll use [kured](https://github.com/kubereboot/kured) that will take care of cordon & drains before rebooting nodes one by one.
+
+{{< highlight file="reboot.tf" >}}
+
+```tf
+resource "helm_release" "kubereboot" {
+  chart      = "kured"
+  version    = "5.1.0"
+  repository = "https://kubereboot.github.io/charts"
+
+  name = "kured"
+
+  set {
+    name  = "configuration.period"
+    value = "1m"
+  }
+
+  set {
+    name  = "tolerations[0].effect"
+    value = "NoSchedule"
+  }
+
+  set {
+    name  = "tolerations[0].operator"
+    value = "Exists"
+  }
+}
+```
+
+{{</ highlight >}}
+
+After applying this, you can check that the daemonset is running on all nodes with `kg ds`.
+
+### Automatic K3s upgrade
+
+kubectl apply -k github.com/rancher/system-upgrade-controller
 
 ## HTTP access