introduce extraInitContainers to helm chart

New extraInitContainers configuration added.
It allows to pass template with a list of containers to execute before
main code-server container started. Main container will only start when
all init containers are  completed (exited with 0 code).

 Additionally changes the way extraContainers is used - instead of
 toYaml use tpl, because this allows to
 reference any values from extraContainers string.

CHANGELOG.md

@@ -3,6 +3,7 @@
 # Changelog
 
 - [Changelog](#changelog)
+  - [Next Version](#next-version)
   - [3.10.1](#3101)
     - [Bug Fixes](#bug-fixes)
     - [Documentation](#documentation)
@@ -51,6 +52,15 @@ VS Code v0.00.0
 
 -->
 
+## Next Version
+
+VS Code v1.56.1
+
+### New Features
+
+- feat: supported `extraInitContainers` in helm chart values
+- feat: changed `extraContainers` to support templating in helm chart
+
 ## 3.10.1
 
 VS Code v1.56.1

ci/helm-chart/README.md

@@ -65,6 +65,7 @@ and their default values.
 | extraArgs | list | `[]` |  |
 | extraConfigmapMounts | list | `[]` |  |
 | extraContainers | string | `""` |  |
+| extraInitContainers | string | `""` |  |
 | extraSecretMounts | list | `[]` |  |
 | extraVars | list | `[]` |  |
 | extraVolumeMounts | list | `[]` |  |
@@ -115,3 +116,47 @@ $ helm upgrade --install code-server ci/helm-chart -f values.yaml
 ```
 
 > **Tip**: You can use the default [values.yaml](values.yaml)
+
+# Extra Containers
+
+There are two parameters which allow to add more containers to pod.
+Use `extraContainers` to add regular containers 
+and `extraInitContainers` to add init containers. You can read more
+about init containers in [k8s documentation](https://kubernetes.io/docs/concepts/workloads/pods/init-containers/).
+
+Both parameters accept strings and use them as a templates
+
+Example of using `extraInitContainers`:
+
+``` yaml
+extraInitContainers: |
+  - name: customization
+    image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
+    imagePullPolicy: IfNotPresent
+    env:
+      - name: SERVICE_URL
+        value: https://open-vsx.org/vscode/gallery
+      - name: ITEM_URL
+        value: https://open-vsx.org/vscode/item
+    command:
+      - sh
+      - -c
+      - |
+        code-server --install-extension ms-python.python
+        code-server --install-extension golang.Go
+    volumeMounts:
+      - name: data
+        mountPath: /home/coder
+
+```
+
+With this yaml in file `init.yaml`, you can execute 
+
+```console
+$ helm upgrade --install code-server \
+    ci/helm-chart \
+    --values init.yaml
+```
+
+to deploy code-server with python and golang extensions preinstalled
+before main container have started. 

ci/helm-chart/templates/deployment.yaml

@@ -43,10 +43,13 @@ spec:
         volumeMounts:
         - name: data
           mountPath: /home/coder
+{{- if .Values.extraInitContainers }}
+{{ tpl .Values.extraInitContainers . | indent 6}}
+{{- end }}
       {{- end }}
       containers:
 {{- if .Values.extraContainers }}
-{{ toYaml .Values.extraContainers | indent 8}}
+{{ tpl .Values.extraContainers . | indent 8}}
 {{- end }}
         - name: {{ .Chart.Name }}
           image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"