add gc add-on

ansible/add-on-roles/garbagecollection/README.md

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+# garbagecollection
+
+this add-on adds a KubeConfig Machineconfiguration as per https://cloud.redhat.com/blog/image-garbage-collection-in-openshift
+This can be used to have a tighter garbagecollection for the images. This may be useful in environments with low disk volume
+
+## Role Variables
+
+see [defaults](defaults/main.yml)
+
+## License
+
+Apache 2.0

ansible/add-on-roles/garbagecollection/defaults/main.yml

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+garbagecollection_high_treshold_percent: 66
+garbagecollection_low_treshold_percent: 50
+garbagecollection_minimum_age: "5m30s"

ansible/add-on-roles/garbagecollection/meta/main.yml

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+galaxy_info:
+  author: Steffen Luetzenkirchen
+  description: configures tight garbage collection for ocp4
+  company: Red Hat
+
+  license: Apache-2.0
+
+  min_ansible_version: 2.9
+
+  platforms:
+    - name: OpenShift
+      versions:
+        - all
+  galaxy_tags:
+    []
+
+dependencies:
+  []
+  # List your role dependencies here, one per line. Be sure to remove the '[]' above,
+  # if you add dependencies to this list.

ansible/add-on-roles/garbagecollection/tasks/post-install.yml

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+---
+- name: Ensure GarbageCollection machineconfig
+  delegate_to: localhost
+  kubernetes.core.k8s:
+    state: present
+    kubeconfig: "{{ k8s_kubeconfig }}"
+    host: "{{ k8s_host }}"
+    ca_cert: "{{ k8s_ca_cert }}"
+    client_cert: "{{ k8s_client_cert }}"
+    client_key: "{{ k8s_client_key }}"
+    definition: "{{ lookup('template', 'templates/cluster-garbagecollection-machineconfig.yml.j2') }}"
+  vars:
+    role: "{{ loop_role }}"
+  with_items:
+    - master
+    - worker
+  loop_control:
+    loop_var: loop_role

ansible/add-on-roles/garbagecollection/templates/cluster-garbagecollection-machineconfig.yml.j2

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+apiVersion: machineconfiguration.openshift.io/v1
+kind: KubeletConfig
+metadata:
+  labels:
+    machineconfiguration.openshift.io/role: {{ role }}
+  name: 60-{{ role }}-kubeconfig-tight-garbage
+spec:
+  kubeletConfig:
+    imageGCHighThresholdPercent: {{ garbagecollection_high_treshold_percent }}
+    imageGCLowThresholdPercent: {{ garbagecollection_low_treshold_percent }}
+    imageMinimumGCAge: "{{ garbagecollection_minimum_age }} "
+  machineConfigPoolSelector:
+    matchLabels:
+      pools.operator.machineconfiguration.openshift.io/{{ role }}: ""