Fix breakage when ignoring all kubeadm preflight errors (#12618)

kubeadm errors out if 'all' is specified with specific checks, so check
that case when we add hardcoded checks.

Add a test to catch regression.

Co-authored-by: Max Gautier <mg@max.gautier.name>

roles/kubernetes/kubeadm/tasks/main.yml

@@ -86,13 +86,13 @@
     - not kubelet_conf.stat.exists
   vars:
     ignored:
-      - DirAvailable--etc-kubernetes-manifests
+      - "{{ 'DirAvailable--etc-kubernetes-manifests' if 'all' not in kubeadm_ignore_preflight_errors }}"
       - "{{ kubeadm_ignore_preflight_errors }}"
   command: >-
     timeout -k {{ kubeadm_join_timeout }} {{ kubeadm_join_timeout }}
     {{ bin_dir }}/kubeadm join
     --config {{ kube_config_dir }}/kubeadm-client.conf
-    --ignore-preflight-errors={{ ignored | flatten | join(',') }}
+    --ignore-preflight-errors={{ ignored | select | flatten | join(',') }}
     --skip-phases={{ kubeadm_join_phases_skip | join(',') }}
 
 - name: Update server field in kubelet kubeconfig

tests/files/packet_ubuntu20-flannel-ha.yml

@@ -9,3 +9,7 @@ etcd_deployment_type: kubeadm
 kubeadm_certificate_key: 3998c58db6497dd17d909394e62d515368c06ec617710d02edea31c06d741085
 skip_non_kubeadm_warning: true
 kube_asymmetric_encryption_algorithm: "RSA-4096"
+
+# This test the variable usage, it is not a prerequisite of the test itself
+kubeadm_ignore_preflight_errors:
+  - all