feat(common): add support for cnpg cluster hibernation without using annotations (#420)

**Description**
cluster hibernation is a good way to get CNPG to scale down to 0
cleanly.
This might(!) be a potential solution for fixing the broken stop button
on SCALE as well, but that's not fully clear as of yet.

This also scales down the poolers to 0 as well. To ensure nothing
remains active.

**⚙️ Type of change**

- [x] ⚙️ Feature/App addition
- [ ] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code

**🧪 How Has This Been Tested?**
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**✔️ Checklist:**

- [x] ⚖️ My code follows the style guidelines of this project
- [x] 👀 I have performed a self-review of my own code
- [x] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [x] 📄 I have made corresponding changes to the documentation
- [x] ⚠️ My changes generate no new warnings
- [x] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [x] ⬆️ I increased versions for any altered app according to semantic
versioning

**➕ App addition**

If this PR is an app addition please make sure you have done the
following.

- [ ] 🪞 I have opened a PR on
[truecharts/containers](https://github.com/truecharts/containers) adding
the container to TrueCharts mirror repo.
- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

---

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library/common-test/Chart.yaml

@@ -3,7 +3,7 @@ appVersion: ""
 dependencies:
 - name: common
   repository: file://../common
-  version: ~12.6.0
+  version: ~12.7.0
 deprecated: false
 description: Helper chart to test different use cases of the common library
 home: https://github.com/truecharts/apps/tree/master/charts/library/common-test

library/common/Chart.yaml

@@ -15,4 +15,4 @@ maintainers:
 name: common
 sources: null
 type: library
-version: 12.6.9
+version: 12.7.0

library/common/templates/class/_cnpgCluster.tpl

@@ -15,14 +15,16 @@ apiVersion: {{ include "tc.v1.common.capabilities.cnpg.cluster.apiVersion" $ }}
 kind: Cluster
 metadata:
   name: {{ $cnpgClusterName }}
-  {{- $labels := (mustMerge ($cnpgClusterLabels | default dict) (include "tc.v1.common.lib.metadata.allLabels" $ | fromYaml)) -}}
-  {{- with (include "tc.v1.common.lib.metadata.render" (dict "rootCtx" $ "labels" $labels) | trim) }}
+  {{- $labels := (mustMerge ($cnpgClusterLabels | default dict) (include "tc.v1.common.lib.metadata.allLabels" $ | fromYaml)) }}
   labels:
+    cnpg.io/reload: "on"
+  {{- with (include "tc.v1.common.lib.metadata.render" (dict "rootCtx" $ "labels" $labels) | trim) }}
     {{- . | nindent 4 }}
   {{- end }}
-  {{- $annotations := (mustMerge ($cnpgClusterAnnotations | default dict) (include "tc.v1.common.lib.metadata.allAnnotations" $ | fromYaml)) -}}
-  {{- with (include "tc.v1.common.lib.metadata.render" (dict "rootCtx" $ "annotations" $annotations) | trim) }}
+  {{- $annotations := (mustMerge ($cnpgClusterAnnotations | default dict) (include "tc.v1.common.lib.metadata.allAnnotations" $ | fromYaml)) }}
   annotations:
+    cnpg.io/hibernation: {{ if $values.hibernate }}"on"{{ else }}"off"{{ end }}
+  {{- with (include "tc.v1.common.lib.metadata.render" (dict "rootCtx" $ "annotations" $annotations) | trim) }}
     {{- . | nindent 4 }}
   {{- end }}
 spec:
@@ -64,7 +66,7 @@ spec:
 
   nodeMaintenanceWindow:
     inProgress: false
-    reusePVC: on
+    reusePVC: true
 
   postgresql:
     {{- tpl ( $values.postgresql | toYaml ) $ | nindent 4 }}

library/common/templates/class/_cnpgPooler.tpl

@@ -21,7 +21,7 @@ spec:
   cluster:
     name: {{ $cnpgClusterName }}
 
-  instances: {{ $values.pooler.instances | default 2 }}
+  instances: {{ if $values.hibernate}}0{{ else }}{{ $values.pooler.instances | default 2 }}{{ end }}
   type: {{ $values.pooler.type }}
   pgbouncer:
     poolMode: session

library/common/values.yaml

@@ -705,6 +705,8 @@ cnpg:
   main:
     enabled: false
     primary: true
+    # -- Puts the cnpg cluster in hibernation mode
+    hibernate: false
     # -- number of instances for both postgres and pgbouncer
     instances: 2
     database: "app"
@@ -724,6 +726,7 @@ cnpg:
     storage:
       size: "256Gi"
       walsize: "256Gi"
+    # -- Gets scaled to 0 if hibernation is true
     pooler:
       instances: 2
     # -- set to enable prometheus metrics