Change default in prometheus storage type to emptydir

Only create pvcs when openshift_prometheus_<alertmanager|buffer>_storage_type==pvc
By default deployment will use emptydir.
Add some documentation and examples.

bz: https://bugzilla.redhat.com/show_bug.cgi?id=1495446

inventory/byo/hosts.example

@@ -632,6 +632,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_storage_volume_name=prometheus
 #openshift_prometheus_storage_volume_size=10Gi
 #openshift_prometheus_storage_labels={'storage': 'prometheus'}
+#openshift_prometheus_storage_type='pvc'
 # For prometheus-alertmanager
 #openshift_prometheus_alertmanager_storage_kind=nfs
 #openshift_prometheus_alertmanager_storage_access_modes=['ReadWriteOnce']
@@ -640,6 +641,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_alertmanager_storage_volume_name=prometheus-alertmanager
 #openshift_prometheus_alertmanager_storage_volume_size=10Gi
 #openshift_prometheus_alertmanager_storage_labels={'storage': 'prometheus-alertmanager'}
+#openshift_prometheus_alertmanager_storage_type='pvc'
 # For prometheus-alertbuffer
 #openshift_prometheus_alertbuffer_storage_kind=nfs
 #openshift_prometheus_alertbuffer_storage_access_modes=['ReadWriteOnce']
@@ -648,6 +650,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_alertbuffer_storage_volume_name=prometheus-alertbuffer
 #openshift_prometheus_alertbuffer_storage_volume_size=10Gi
 #openshift_prometheus_alertbuffer_storage_labels={'storage': 'prometheus-alertbuffer'}
+#openshift_prometheus_alertbuffer_storage_type='pvc'
 #
 # Option B - External NFS Host
 # NFS volume must already exist with path "nfs_directory/_volume_name" on
@@ -660,6 +663,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_storage_volume_name=prometheus
 #openshift_prometheus_storage_volume_size=10Gi
 #openshift_prometheus_storage_labels={'storage': 'prometheus'}
+#openshift_prometheus_storage_type='pvc'
 # For prometheus-alertmanager
 #openshift_prometheus_alertmanager_storage_kind=nfs
 #openshift_prometheus_alertmanager_storage_access_modes=['ReadWriteOnce']
@@ -668,6 +672,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_alertmanager_storage_volume_name=prometheus-alertmanager
 #openshift_prometheus_alertmanager_storage_volume_size=10Gi
 #openshift_prometheus_alertmanager_storage_labels={'storage': 'prometheus-alertmanager'}
+#openshift_prometheus_alertmanager_storage_type='pvc'
 # For prometheus-alertbuffer
 #openshift_prometheus_alertbuffer_storage_kind=nfs
 #openshift_prometheus_alertbuffer_storage_access_modes=['ReadWriteOnce']
@@ -676,6 +681,7 @@ openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true',
 #openshift_prometheus_alertbuffer_storage_volume_name=prometheus-alertbuffer
 #openshift_prometheus_alertbuffer_storage_volume_size=10Gi
 #openshift_prometheus_alertbuffer_storage_labels={'storage': 'prometheus-alertbuffer'}
+#openshift_prometheus_alertbuffer_storage_type='pvc'
 #
 # Option C - none -- Prometheus, alertmanager and alertbuffer will use emptydir volumes
 # which are destroyed when pods are deleted

roles/openshift_prometheus/README.md

@@ -24,7 +24,7 @@ For default values, see [`defaults/main.yaml`](defaults/main.yaml).
 ## PVC related variables
 Each prometheus component (prometheus, alertmanager, alertbuffer) can set pv claim by setting corresponding role variable:
 ```
-openshift_prometheus_<COMPONENT>_storage_type: <VALUE>
+openshift_prometheus_<COMPONENT>_storage_type: <VALUE> (pvc, emptydir)
 openshift_prometheus_<COMPONENT>_pvc_(name|size|access_modes|pv_selector): <VALUE>
 ```
 e.g

roles/openshift_prometheus/defaults/main.yaml

@@ -16,19 +16,22 @@ openshift_prometheus_image_alertbuffer: "openshift/prometheus-alert-buffer:v0.0.
 openshift_prometheus_additional_rules_file: null
 
 # storage
-openshift_prometheus_storage_type: pvc
+# One of ['emptydir', 'pvc']
+openshift_prometheus_storage_type: "emptydir"
 openshift_prometheus_pvc_name: prometheus
 openshift_prometheus_pvc_size: "{{ openshift_prometheus_storage_volume_size | default('10Gi') }}"
 openshift_prometheus_pvc_access_modes: [ReadWriteOnce]
 openshift_prometheus_pvc_pv_selector: "{{ openshift_prometheus_storage_labels | default({}) }}"
 
-openshift_prometheus_alertmanager_storage_type: pvc
+# One of ['emptydir', 'pvc']
+openshift_prometheus_alertmanager_storage_type: "emptydir"
 openshift_prometheus_alertmanager_pvc_name: prometheus-alertmanager
 openshift_prometheus_alertmanager_pvc_size: "{{ openshift_prometheus_alertmanager_storage_volume_size | default('10Gi') }}"
 openshift_prometheus_alertmanager_pvc_access_modes: [ReadWriteOnce]
 openshift_prometheus_alertmanager_pvc_pv_selector: "{{ openshift_prometheus_alertmanager_storage_labels | default({}) }}"
 
-openshift_prometheus_alertbuffer_storage_type: pvc
+# One of ['emptydir', 'pvc']
+openshift_prometheus_alertbuffer_storage_type: "emptydir"
 openshift_prometheus_alertbuffer_pvc_name: prometheus-alertbuffer
 openshift_prometheus_alertbuffer_pvc_size: "{{ openshift_prometheus_alertbuffer_storage_volume_size | default('10Gi') }}"
 openshift_prometheus_alertbuffer_pvc_access_modes: [ReadWriteOnce]

roles/openshift_prometheus/tasks/install_prometheus.yaml

@@ -128,6 +128,7 @@
     access_modes: "{{ openshift_prometheus_pvc_access_modes }}"
     volume_capacity: "{{ openshift_prometheus_pvc_size }}"
     selector: "{{ openshift_prometheus_pvc_pv_selector }}"
+  when: openshift_prometheus_storage_type == 'pvc'
 
 - name: create alertmanager pvc
   oc_pvc:
@@ -136,6 +137,7 @@
     access_modes: "{{ openshift_prometheus_alertmanager_pvc_access_modes }}"
     volume_capacity: "{{ openshift_prometheus_alertmanager_pvc_size }}"
     selector: "{{ openshift_prometheus_alertmanager_pvc_pv_selector }}"
+  when: openshift_prometheus_alertmanager_storage_type == 'pvc'
 
 - name: create alertbuffer pvc
   oc_pvc:
@@ -144,6 +146,7 @@
     access_modes: "{{ openshift_prometheus_alertbuffer_pvc_access_modes }}"
     volume_capacity: "{{ openshift_prometheus_alertbuffer_pvc_size }}"
     selector: "{{ openshift_prometheus_alertbuffer_pvc_pv_selector }}"
+  when: openshift_prometheus_alertbuffer_storage_type == 'pvc'
 
 # create prometheus stateful set
 - name: Set prometheus template