Added README.md for roles

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/k3s_server/README.md

@@ -0,0 +1,49 @@
+# K3s Server Ansible Role
+
+This Ansible role installs and configures a K3s server cluster.
+
+## Role Variables
+
+- `k3s_primary_server_ip`: The IP address of the primary K3s server.
+- `k3s_server_name`: The server name for the K3s cluster.
+- `k3s_cluster_name`: The name for the K3s cluster in the kubeconfig.
+- `k3s_user_name`: The user name for the K3s cluster in the kubeconfig.
+- `k3s_context_name`: The context name for the K3s cluster in the kubeconfig.
+- `k3s_server_token_vault_file`: The path to the Ansible Vault file containing the K3s token. Default is `../vars/group_vars/k3s/secrets_token.yml`.
+
+## Tasks
+
+The main tasks are:
+
+1.  **Install dependencies**: Installs `qemu-guest-agent`.
+2.  **Primary Server Installation**:
+    - Downloads the K3s installation script.
+    - Installs the K3s server on the primary node with a TLS SAN.
+3.  **Pull Token**:
+    - Retrieves the K3s token from the primary server.
+    - Stores the token in an Ansible Vault encrypted file.
+4.  **Secondary Server Installation**:
+    - Installs K3s on the secondary servers, joining them to the cluster using the token from the vault.
+5.  **Create Kubeconfig**:
+    - Slurps the `k3s.yaml` from the primary server.
+    - Creates a kubeconfig file on the local machine for accessing the cluster.
+
+## Handlers
+
+- `Restart k3s`: Restarts the K3s service.
+
+## Usage
+
+Here is an example of how to use this role in a playbook:
+
+```yaml
+- hosts: k3s_servers
+  roles:
+    - role: k3s_server
+      vars:
+        k3s_primary_server_ip: "192.168.1.100"
+        k3s_server_name: "k3s.example.com"
+        k3s_cluster_name: "my-k3s-cluster"
+        k3s_user_name: "my-k3s-user"
+        k3s_context_name: "my-k3s-context"
+```