Add support for container lifecycle hooks

This is already supported by JupyterHub and gives
a simple way for people to for example add custom CA
without requiring image rebuild.

Author: sgaist

helm-chart/binderhub/templates/deployment.yaml

@@ -70,6 +70,10 @@ spec:
         args:
           - --config
           - /etc/binderhub/config/binderhub_config.py
+        {{- with .Values.lifecycle }}
+        lifecycle:
+          {{- . | toYaml | nindent 10 }}
+        {{- end }}
         volumeMounts:
           - mountPath: /etc/binderhub/config/
             name: config

helm-chart/binderhub/values.yaml

@@ -211,6 +211,7 @@ ingress:
     #     - chart-example.local
 
 initContainers: []
+lifecycle: {}
 extraVolumes: []
 extraVolumeMounts: []
 extraEnv: []