support custom templates via helm

- top-level templates is dict of filename: contents, e.g. "page.html": "{% extends "templates/page.html" %}"
- mount custom templates dir in /etc/binderhub/templates

Existing template config already supports this, so it's just making the files available we need.

helm-chart/binderhub/files/binderhub_config.py

@@ -38,6 +38,8 @@ def get_value(key, default=None):
             value = value[level]
     return value
 
+# load custom templates, by default
+c.BinderHub.template_path = "/etc/binderhub/templates"
 
 # load config from values.yaml
 for section, sub_cfg in get_value("config", {}).items():

helm-chart/binderhub/schema.yaml

@@ -25,6 +25,7 @@ required:
   - service
   - config
   - extraConfig
+  - templates
   - jupyterhub
   - deployment
   - dind
@@ -260,6 +261,14 @@ properties:
       manifest as either the binder pod going into `Error` or `CrashLoopBackoff` states, or in
       some special cases, the binder pod running but... just doing very random things. Be careful!
 
+  templates:
+    type: object
+    additionalProperties:
+      type: string
+    description: |
+      Custom HTML page templates for BinderHub,
+      e.g. page.html.
+
   jupyterhub:
     type: object
     additionalProperties: true
@@ -479,7 +488,7 @@ properties:
         description: |
           The path type to use. The default value is 'Prefix'. Only applies on Kubernetes v1.18+.
 
-          See [the Kubernetes documentation](https://kubernetes.io/docs/concepts/services-networking/ingress/#path-types) 
+          See [the Kubernetes documentation](https://kubernetes.io/docs/concepts/services-networking/ingress/#path-types)
           for more details about path types.
       tls:
         type: array

helm-chart/binderhub/templates/deployment.yaml

@@ -45,6 +45,14 @@ spec:
       - name: config
         secret:
           secretName: binder-secret
+      - name: templates
+        secret:
+          secretName: binder-secret
+          items:
+            {{- range $filename, $contents := .Values.templates }}
+            - key: "templates-{{ $filename }}"
+              path: {{ $filename | quote }}
+            {{- end }}
       {{- if .Values.config.BinderHub.use_registry }}
       - name: docker-secret
         secret:
@@ -54,6 +62,7 @@ spec:
         hostPath:
           path: /var/run/docker.sock
       {{- end }}
+
       {{- with .Values.extraVolumes }}
       {{- . | toYaml | nindent 6 }}
       {{- end }}
@@ -71,6 +80,9 @@ spec:
           - mountPath: /etc/binderhub/config/
             name: config
             readOnly: true
+          - mountPath: /etc/binderhub/templates/
+            name: templates
+            readOnly: true
           {{- if .Values.config.BinderHub.use_registry }}
           - mountPath: /root/.docker
             name: docker-secret

helm-chart/binderhub/templates/secret.yaml

@@ -18,6 +18,12 @@ stringData:
   values.yaml: |
     {{- pick .Values "config" "cors" "dind" "extraConfig" | toYaml | nindent 4 }}
 
+  {{- /* Custom HTML templates */ -}}
+  {{- range $filename, $contents := .Values.templates }}
+  templates-{{ $filename }}: |
+    {{ $contents | nindent 4 }}
+  {{- end }}
+
   {{- /* Glob files to allow them to be mounted by the binderhub pod */}}
   {{- /* key=filename: value=content */}}
   {{- (.Files.Glob "files/*").AsConfig | nindent 2 }}

helm-chart/binderhub/values.yaml

@@ -41,6 +41,8 @@ config:
 
 extraConfig: {}
 
+templates: {}
+
 # Two bits of config need to be set to fully enable cors.
 # config.BinderHub.cors_allow_origin controls the allowed origins for the
 # binderhub api, and jupyterhub.hub.config.BinderSpawner.cors_allow_origin
@@ -281,16 +283,14 @@ ingress:
     type: kube-lego
   hosts: []
   ingressClassName:
-  annotations:
-    {}
+  annotations: {}
     # kubernetes.io/ingress.class: nginx
     # kubernetes.io/tls-acme: "true"
   pathSuffix:
     # Suffix added to Ingress's routing path pattern.
     # Specify `*` if your ingress matches path by glob pattern.
   pathType: Prefix
-  tls:
-    []
+  tls: []
     # Secrets must be manually created in the namespace.
     # - secretName: chart-example-tls
     #   hosts:

testing/k8s-binder-k8s-hub/binderhub-chart-config.yaml

@@ -14,6 +14,14 @@ config:
     log_level: 10
     cors_allow_origin: "*"
 
+templates:
+  page.html: |
+    {% extends "templates/page.html" %}
+    {% block footer %}
+    {{ super() }}
+    <span>test-template</span>
+    {% endblock %}
+
 ingress:
   # Enabled to test the creation/update of the k8s Ingress resource, but not
   # used actively in our CI system.