Documentation, and validation logic for HA configuration added.

README.md

@@ -72,6 +72,11 @@ consistency.
 | `k3s_disable_cloud_controller` | Disable k3s default cloud controller manager.                            | `false`                        |
 | `k3s_disable_network_policy`   | Disable k3s default network policy controller.                           | `false`                        |
 | `k3s_write_kubeconfig_mode`    | Define the file mode from the generated KubeConfig, eg. `644`            | _NULL_                         |
+| `k3s_datastore_endpoint`       | Define the database or etcd cluster endpoint for HA.                     | _NULL_                         |
+| `k3s_datastore_cafile`         | Define the database TLS CA file.                                         | _NULL_                         |
+| `k3s_datastore_certfile`       | Define the database TLS Cert file.                                       | _NULL_                         |
+| `k3s_datastore_keyfile`        | Define the database TLS Key file.                                        | _NULL_                         |
+| `k3s_dqlite_datastore`         | Use DQLite as the database backend for HA. (EXPERIMENTAL)                | `false`                        |
 
 #### Important note about `k3s_release_version`
 
@@ -121,13 +126,25 @@ Below are variables that are set against specific hosts in your inventory.
 | `k3s_node_data_dir`         | Folder to hold state.                                                    | `/var/lib/rancher/k3s` |
 | `k3s_tls_san`               | Add additional hosname or IP as Subject Alternate Name in the TLS cert.  | _NULL_                 |
 
-#### Important note about `k3s_control_node`
+#### Important note about `k3s_control_node` and High Availability (HA)
 
-Currently only one host can be defined as a control node, if multiple hosts are
-set to true the play will fail.
+By default only one host will be defined as a control node by Ansible, If you 
+do not set a host as a control node, the role will automatically delegate
+the first play host as a control node (master). This is not suitable for use in
+a Production workload.
 
-If you do not set a host as a control node, the role will automatically delegate
-the first play host as a control node.
+If multiple hosts have `k3s_control_node` set to true, you must also set
+`k3s_datastore_endpoint` as the connection string to a MySQL or PostgreSQL
+database, or etcd cluster else the play will fail.
+
+If using TLS, the CA, Certificate and Key need to already be available on
+the play hosts.
+
+See: [High Availability with an External DB](https://rancher.com/docs/k3s/latest/en/installation/ha/)
+
+Since K3s v1.0.0 it is possible to use DQLite as the backend database, and this
+is done by setting `k3s_dqlite_datastore` to true. As this is an experimental
+feature you will also need to set `k3s_use_experimental` to true.
 
 #### Important note about `k3s_flannel_interface`
 

defaults/main.yml

@@ -17,6 +17,27 @@ k3s_install_dir: /usr/local/bin
 # Use experimental features in k3s?
 k3s_use_experimental: false
 
+# Use a database or etcd cluster to enable HA. Examples below:
+# MySQL:
+#   k3s_datastore_endpoint "mysql://username:password@tcp(hostname:3306)/database-name"
+# PostgreSQL:
+#   k3s_datastore_endpoint: "postgres://username:password@hostname:port/database-name"
+# Etcd:
+#   k3s_datastore_endpoint: "https://etcd-host-1:2379,https://etcd-host-2:2379,https://etcd-host-3:2379"
+k3s_datastore_endpoint: false
+
+# If using a database endpoint for HA, you can optionally set the CA file,
+# Cert file and Key file for connecting to the database using TLS.
+#
+# These need to already be present on the play hosts.
+#
+# k3s_datastore_cafile: /path/to/ca.crt
+# k3s_datastore_certfile: /path/to/cert.crt
+# k3s_datastore_keyfile: /path/to/key.pem
+
+# Use DQLite for HA Datastore? (EXPERIMENTAL)
+k3s_dqlite_datastore: false
+
 # Are control hosts also worker nodes?
 k3s_control_workers: true
 

tasks/validate/check-experimental-variables.yml

@@ -1,9 +1,10 @@
 ---
 
-- name: Check k3s_non_root is enabled with k3s_use_experimental
+- name: Check if any experimental variables are configure and if they are enabled with k3s_use_experimental
   assert:
     that:
       - k3s_use_experimental is defined and k3s_use_experimental
+      - k3s_dqlite_datastore is defined and k3s_use_experimental
     success_msg: "Experimental variables are defined and enabled."
     fail_msg: "Experimental variables have been configured. If you want to use them ensure you set k3s_use_experimental"
   when: k3s_non_root is defined and k3s_non_root

tasks/validate/check-master-count.yml

@@ -1,8 +1,21 @@
 ---
 
-- name: Check if multiple controllers defined
+- name: Check the conditions when a single controller is defined
   assert:
     that:
-      - k3s_controller_count | length == 1
-    success_msg: "Only one controller has been defined."
-    fail_msg: "Multiple controllers have been defined. This is not yet supported."
+      - (k3s_controller_count | length == 1)
+        and (k3s_datastore_endpoint is not defined or not k3s_datastore_endpoint)
+        and (k3s_dqlite_datastore is not defined or not k3s_dqlite_datastore)
+    success_msg: "Control plane configuration is valid."
+    fail_msg: "Control plane configuration is invalid. Please see notes about k3s_control_node and HA in README.md."
+  when: k3s_controller_count | length == 1
+
+- name: Check the conditions when multiple controllers are defined
+  assert:
+    that:
+      - (k3s_controller_count | length >= 2)
+        and ((k3s_datastore_endpoint is defined and k3s_datastore_endpoint)
+              or k3s_dqlite_datastore is defined and k3s_dqlite_datastore)
+    success_msg: "Control plane configuration is valid."
+    fail_msg: "Control plane configuration is invalid. Please see notes about k3s_control_node and HA in README.md."
+  when: k3s_controller_count | length >= 2

tasks/validate/check-variables.yml

@@ -137,3 +137,43 @@
     success_msg: "--disable-scheduler supported in {{ k3s_release_version }}"
     fail_msg: "--disable-scheduler not supported in {{ k3s_release_version }}"
   when: k3s_disable_scheduler is defined and k3s_disable_scheduler
+
+- name: Check k3s_datastore_endpoint against k3s version
+  assert:
+    that:
+      - (k3s_release_version | replace('v', '')) is version_compare('1.0.0', '>=')
+    success_msg: "--datastore-endpoint supported in {{ k3s_release_version }}"
+    fail_msg: "--datastore-endpoint not supported in {{ k3s_release_version }}"
+  when: k3s_datastore_endpoint is defined and k3s_datastore_endpoint
+
+- name: Check k3s_dqlite_datastore against k3s version
+  assert:
+    that:
+      - (k3s_release_version | replace('v', '')) is version_compare('1.0.0', '>=')
+    success_msg: "--cluster-init supported in {{ k3s_release_version }}"
+    fail_msg: "--cluster-init not supported in {{ k3s_release_version }}"
+  when: k3s_dqlite_datastore is defined and k3s_dqlite_datastore
+
+- name: Check k3s_datastore_cafile against k3s version
+  assert:
+    that:
+      - (k3s_release_version | replace('v', '')) is version_compare('1.0.0', '>=')
+    success_msg: "--datastore-endpoint supported in {{ k3s_release_version }}"
+    fail_msg: "--datastore-endpoint not supported in {{ k3s_release_version }}"
+  when: k3s_datastore_cafile is defined and k3s_datastore_cafile
+
+- name: Check k3s_datastore_certfile against k3s version
+  assert:
+    that:
+      - (k3s_release_version | replace('v', '')) is version_compare('1.0.0', '>=')
+    success_msg: "--datastore-endpoint supported in {{ k3s_release_version }}"
+    fail_msg: "--datastore-endpoint not supported in {{ k3s_release_version }}"
+  when: k3s_datastore_certfile is defined and k3s_datastore_certfile
+
+- name: Check k3s_datastore_keyfile against k3s version
+  assert:
+    that:
+      - (k3s_release_version | replace('v', '')) is version_compare('1.0.0', '>=')
+    success_msg: "--datastore-endpoint supported in {{ k3s_release_version }}"
+    fail_msg: "--datastore-endpoint not supported in {{ k3s_release_version }}"
+  when: k3s_datastore_keyfile is defined and k3s_datastore_keyfile