feat: Make it possible to customize k8s resources

CHANGELOG.md

@@ -17,6 +17,7 @@ Every user-facing change should have an entry in this changelog. Please respect
 -->
 
 ## Unreleased
+- [Improvement] Make it possible to override k8s resources in plugins using `k8s-override` patch. (by @foadlind)
 
 ## v14.0.2 (2022-06-27)
 

docs/k8s.rst

@@ -140,3 +140,30 @@ Updating docker images
 Kubernetes does not provide a single command for updating docker images out of the box. A `commonly used trick <https://github.com/kubernetes/kubernetes/issues/33664>`__ is to modify an innocuous label on all resources::
 
     kubectl patch -k "$(tutor config printroot)/env" --patch "{\"spec\": {\"template\": {\"metadata\": {\"labels\": {\"date\": \"`date +'%Y%m%d-%H%M%S'`\"}}}}}"
+
+
+.. _customizing_kubernetes_sources:
+
+Customizing Kubernetes resources
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Plugins can customize any Kubernetes resource in Tutor by overriding the definition of the resource with a :patch:`k8s-override` patch. For example, to change the volume size for MongoDB from ``5Gi`` to ``10Gi``, add the following to the plugin:
+
+::
+
+    # myplugin/tutormyplugin/patches/k8s-override
+
+    apiVersion: v1
+    kind: PersistentVolumeClaim
+    metadata:
+      name: mongodb
+      labels:
+        app.kubernetes.io/component: volume
+        app.kubernetes.io/name: mongodb
+    spec:
+      accessModes:
+        - ReadWriteOnce
+      resources:
+        requests:
+          storage: 10Gi
+

docs/reference/patches.rst

@@ -90,6 +90,15 @@ File: ``k8s/deployments.yml``
 
 File: ``k8s/jobs.yml``
 
+.. patch:: k8s-override
+
+``k8s-override``
+================
+
+File: ``k8s/override.yml``
+
+Any Kubernetes resource definition in this patch will override the resource defined by Tutor, provided that their names match. See :ref:`Customizing Kubernetes resources <customizing_kubernetes_sources>` for an example.
+
 .. patch:: k8s-services
 
 ``k8s-services``
@@ -125,6 +134,15 @@ File: ``kustomization.yml``
 
 File: ``kustomization.yml``
 
+.. patch:: kustomization-patches-strategic-merge
+
+``kustomization-patches-strategic-merge``
+=========================================
+
+File: ``kustomization.yml``
+
+This can be used to add more Kustomization patches that make use of the `strategic merge mechanism <https://kubernetes.io/docs/tasks/manage-kubernetes-objects/kustomization/#customizing>`__. 
+
 .. patch:: kustomization-resources
 
 ``kustomization-resources``

tutor/templates/k8s/override.yml

@@ -0,0 +1 @@
+{{ patch("k8s-override") }}

tutor/templates/kustomization.yml

@@ -59,4 +59,8 @@ configMapGenerator:
         app.kubernetes.io/name: redis
 {{ patch("kustomization-configmapgenerator") }}
 
+patchesStrategicMerge:
+- k8s/override.yml
+{{ patch("kustomization-patches-strategic-merge") }}
+
 {{ patch("kustomization") }}