Test single-node cluster (#78)

* Molecule: Derive overrides.yml location from scenario dir

# Conflicts:
#	molecule/default/molecule.yml
#	molecule/ipv6/molecule.yml

* Molecule: Add single_node scenario

* Fix get_nodes test for the case of empty groups

.github/workflows/test.yml

@@ -15,6 +15,8 @@ jobs:
       matrix:
         scenario:
           - default
+          - single_node
+      fail-fast: false
     env:
       PYTHON_VERSION: "3.10"
 

molecule/README.md

@@ -8,6 +8,8 @@ We have these scenarios:
 
 - **default**:
   A 3 control + 2 worker node cluster based very closely on the [sample inventory](../inventory/sample/).
+- **single_node**:
+  Very similar to the default scenario, but uses only a single node for all cluster functionality.
 
 ## How to execute
 
@@ -29,7 +31,7 @@ Furthermore, the test cluster uses the `192.168.30.0/24` subnet which is [not se
 To set the subnet up for use with VirtualBox, please make sure that `/etc/vbox/networks.conf` exists and that it contains this line:
 
 ```
-* 192.168.30.0/24`
+* 192.168.30.0/24
 ```
 
 ### Install Python dependencies

molecule/default/molecule.yml

@@ -53,8 +53,6 @@ provisioner:
   inventory:
     links:
       group_vars: ../../inventory/sample/group_vars
-  env:
-    OVERRIDES_FILE: ../default/overrides.yml
 scenario:
   test_sequence:
     - dependency

molecule/resources/converge.yml

@@ -1,7 +1,7 @@
 ---
 - name: Apply overrides
   ansible.builtin.import_playbook: >-
-    {{ lookup("ansible.builtin.env", "OVERRIDES_FILE") }}
+    {{ lookup("ansible.builtin.env", "MOLECULE_SCENARIO_DIRECTORY") }}/overrides.yml
 
 - name: Converge
   ansible.builtin.import_playbook: ../../site.yml

molecule/resources/reset.yml

@@ -1,7 +1,7 @@
 ---
 - name: Apply overrides
   ansible.builtin.import_playbook: >-
-    {{ lookup("ansible.builtin.env", "OVERRIDES_FILE") }}
+    {{ lookup("ansible.builtin.env", "MOLECULE_SCENARIO_DIRECTORY") }}/overrides.yml
 
 - name: Reset
   ansible.builtin.import_playbook: ../../reset.yml

molecule/resources/verify/from_outside/tasks/test/get-nodes.yml

@@ -12,6 +12,13 @@
     fail_msg: "Expected nodes {{ expected_nodes }}, but found nodes {{ found_nodes }}"
   vars:
     found_nodes: >-
-      {{ cluster_nodes | json_query('resources[*].metadata.name') | unique }}
-    expected_nodes: >-
-      {{ (groups['master'] + groups['node']) | unique }}
+      {{ cluster_nodes | json_query('resources[*].metadata.name') | unique | sort }}
+    expected_nodes: |-
+      {{
+        (
+          ( groups['master'] | default([]) ) +
+          ( groups['node'] | default([]) )
+        )
+        | unique
+        | sort
+      }}

molecule/single_node/molecule.yml

@@ -0,0 +1,48 @@
+---
+dependency:
+  name: galaxy
+driver:
+  name: vagrant
+platforms:
+  - name: control1
+    box: generic/ubuntu2204
+    memory: 4096
+    cpus: 4
+    config_options:
+      # We currently can not use public-key based authentication on Ubuntu 22.04,
+      # see: https://github.com/chef/bento/issues/1405
+      ssh.username: "vagrant"
+      ssh.password: "vagrant"
+    groups:
+      - k3s_cluster
+      - master
+    interfaces:
+      - network_name: private_network
+        ip: 192.168.30.50
+provisioner:
+  name: ansible
+  playbooks:
+    converge: ../resources/converge.yml
+    side_effect: ../resources/reset.yml
+    verify: ../resources/verify.yml
+  inventory:
+    links:
+      group_vars: ../../inventory/sample/group_vars
+scenario:
+  test_sequence:
+    - dependency
+    - lint
+    - cleanup
+    - destroy
+    - syntax
+    - create
+    - prepare
+    - converge
+    # idempotence is not possible with the playbook in its current form.
+    - verify
+    # We are repurposing side_effect here to test the reset playbook.
+    # This is why we do not run it before verify (which tests the cluster),
+    # but after the verify step.
+    - side_effect
+    - cleanup
+    - destroy

molecule/single_node/overrides.yml

@@ -0,0 +1,15 @@
+---
+- name: Apply overrides
+  hosts: all
+  tasks:
+    - name: Override host variables
+      ansible.builtin.set_fact:
+        # See: https://github.com/flannel-io/flannel/blob/67d603aaf45ef80f5dd39f43714fc5e6f8a637eb/Documentation/troubleshooting.md#Vagrant  # noqa yaml[line-length]
+        flannel_iface: eth1
+
+        # The test VMs might be a bit slow, so we give them more time to join the cluster:
+        retry_count: 45
+
+        # Make sure that our IP ranges do not collide with those of the default scenario
+        apiserver_endpoint: "192.168.30.223"
+        metal_lb_ip_range: "192.168.30.91-192.168.30.99"