CH-94 add control on image prepull

Author: filippomc

applications/jupyterhub/deploy/templates/image-puller/_helpers-daemonset.tpl

@@ -199,7 +199,27 @@ spec:
           securityContext:
             {{- . | toYaml | nindent 12 }}
           {{- end }}
+      {{- end }}
+      {{- /* --- EDIT: CLOUDHARNESS pull images --- */}}
+      {{- if $.Values.apps.jupyterhub.harness.jupyterhub.prepull -}}
+        {{- range $k, $v := $.Values.apps.jupyterhub.harness.jupyterhub.prepull }}
+        - name: image-pull--{{ $v }}
+          image: {{ get ( get $.Values "task-images" ) $v }}
+          command:
+            - /bin/sh
+            - -c
+            - echo "Pulling complete"
+          {{- with $.Values.apps.jupyterhub.prePuller.resources }}
+          resources:
+            {{- . | toYaml | nindent 12 }}
+          {{- end }}
+          {{- with $.Values.apps.jupyterhub.prePuller.containerSecurityContext }}
+          securityContext:
+            {{- . | toYaml | nindent 12 }}
+          {{- end }}
         {{- end }}
+      {{- end }}
+      {{- /* --- END EDIT: CLOUDHARNESS pull images --- */}}
       containers:
         - name: pause
           image: {{ .Values.apps.jupyterhub.prePuller.pause.image.name }}:{{ .Values.apps.jupyterhub.prePuller.pause.image.tag }}

applications/jupyterhub/deploy/values-test.yaml

@@ -1 +1,5 @@
-
+harness:
+  jupyterhub:
+    prepull: 
+    - cloudharness-base
+ 

docs/jupyterhub.md

@@ -35,6 +35,7 @@ Edit the `deploy/values.yaml` file `harness.jupyterhub` section  to edit configu
 - `applicationHook`: change the hook function (advances, see below)
 - `extraConfig`: allows you to add Python snippets to the jupyterhub_config.py file
 - `spawnerExtraConfig`: allows you to add values to the spawner object without the need of creating a new hook
+- `prepull`: indicate images that will be prepulled from the current build
 
 Example:
 ```yaml
@@ -46,6 +47,8 @@ harness:
     name: proxy-public
   jupyterhub:
     args: ["--debug", "--NotebookApp.default_url=/lab"]
+    prepull:
+    - cloudharness-base
     extraConfig:
       timing: |
         c.Spawner.port = 8000
@@ -179,4 +182,30 @@ Cloudharness JupyterHub is integrated with the accounts service so enabling a sh
 
 The spawner is also adapted providing a hook to allow other applications to be based on the hub spawner to run with their own configurations.
 
-Available
+Available
+
+## Prepull configuration
+Image prepull can be configured in two ways.
+
+For static images (tag known), can set `prepuller.extraImages` on `applications/jupyterhub/deploy/values.yaml`, like:
+
+```yaml
+prePuller:
+  extraImages:
+    nginx-image:
+      name: nginx
+      tag: latest
+```
+
+For images which build is managed by CloudHarness the tag is unknown during the configuration;
+for this case, can rely on the dynamic configuration through `harness.jupyterhub.prepull` variable, like:
+
+```yaml
+harness:
+  jupyterhub:
+    prepull: 
+    - cloudharness-base
+```
+
+> Note that only built images defined as tasks, base or common can be used here. 
+> If an image is not included, it might be required to include it also as a build dependency or, better, define task images directly inside your jupyterhub application override.