feat(k8s): add Helm module inheritance via the base field

docs/README.md

@@ -8,6 +8,7 @@
   * [Features and usage](./using-garden/features-and-usage.md)
   * [Configuration files](./using-garden/configuration-files.md)
   * [Remote Clusters](./using-garden/remote-clusters.md)
+  * [Using Helm charts](./using-garden/using-helm-charts.md)
   * [Hot Reload](./using-garden/hot-reload.md)
 * [Example projects](./examples/README.md)
   * [Hello world](./examples/hello-world.md)

docs/reference/config.md

@@ -46,15 +46,6 @@ module:
   # Optional.
   repositoryUrl:
 
-  # Variables that this module can reference and expose as environment variables.
-  #
-  # Example:
-  #   my-variable: some-value
-  #
-  # Optional.
-  variables: 
-    {}
-
   # When false, disables pushing this module to remote registries.
   #
   # Optional.
@@ -237,15 +228,6 @@ module:
   # Optional.
   repositoryUrl:
 
-  # Variables that this module can reference and expose as environment variables.
-  #
-  # Example:
-  #   my-variable: some-value
-  #
-  # Optional.
-  variables: 
-    {}
-
   # When false, disables pushing this module to remote registries.
   #
   # Optional.
@@ -409,15 +391,6 @@ module:
   # Optional.
   repositoryUrl:
 
-  # Variables that this module can reference and expose as environment variables.
-  #
-  # Example:
-  #   my-variable: some-value
-  #
-  # Optional.
-  variables: 
-    {}
-
   # When false, disables pushing this module to remote registries.
   #
   # Optional.
@@ -801,15 +774,6 @@ module:
   # Optional.
   repositoryUrl:
 
-  # Variables that this module can reference and expose as environment variables.
-  #
-  # Example:
-  #   my-variable: some-value
-  #
-  # Optional.
-  variables: 
-    {}
-
   # When false, disables pushing this module to remote registries.
   #
   # Optional.
@@ -858,15 +822,29 @@ module:
             # Optional.
             target:
 
-  # A valid Helm chart name or URI. Required if the module doesn't contain the Helm chart itself.
+  # The name of another `helm` module to use as a base for this one. Use this to re-use a Helm
+  # chart across multiple services. For example, you might have an organization-wide base chart
+  # for certain types of services.
+  # If set, this module will by default inherit the following properties from the base module:
+  # `serviceResource`, `values`
+  # Each of those can be overridden in this module. They will be merged with a JSON Merge Patch
+  # (RFC 7396).
+  #
+  # Example: "my-base-chart"
+  #
+  # Optional.
+  base:
+
+  # A valid Helm chart name or URI (same as you'd input to `helm install`). Required if the module
+  # doesn't contain the Helm chart itself.
   #
   # Example: "stable/nginx-ingress"
   #
   # Optional.
   chart:
 
   # The path, relative to the module path, to the chart sources (i.e. where the Chart.yaml file
-  # is, if any).
+  # is, if any). Not used when `base` is specified.
   #
   # Optional.
   chartPath: .
@@ -942,6 +920,12 @@ module:
     hotReloadArgs: 
       -
 
+  # Set this to true if the chart should only be built, but not deployed as a service. Use this,
+  # for example, if the chart should only be used as a base for other modules.
+  #
+  # Optional.
+  skipDeploy: false
+
   # The task definitions for this module.
   #
   # Optional.

docs/using-garden/using-helm-charts.md

@@ -151,3 +151,100 @@ module:
 For hot-reloading to work you must specify `serviceResource.containerModule`, so that Garden knows which module contains the sources to use for hot-reloading. You can then optionally add `serviceResource.hotReloadArgs` to, for example, start the container with automatic reloading or in development mode.
 
 For the above example, you could then run `garden deploy -w --hot-reload=vote` or `garden dev --hot-reload=vote` to start the `vote` service in hot-reloading mode. When you then change the sources in the _vote-image_ module, Garden syncs the changes to the running container from the Helm chart.
+
+## Re-using charts
+
+Often you'll want to re-use the same Helm charts for multiple modules. For example, you might have a generic template
+for all your backend services that configures auto-scaling, secrets/keys, sidecars, routing and so forth, and you don't
+want to repeat those configurations all over the place.
+
+You can achieve this by using the `base` field on the `helm` module type. Staying with our `vote-helm` example project,
+let's look at the `base-chart` and `api` modules:
+
+```yaml
+# base-chart
+module:
+  description: Base Helm chart for services
+  type: helm
+  name: base-chart
+  serviceResource:
+    kind: Deployment
+  skipDeploy: true
+```
+
+```yaml
+# api
+module:
+  description: The API backend for the voting UI
+  type: helm
+  name: api
+  base: base-chart
+  serviceResource:
+    containerModule: api-image
+  dependencies:
+    - redis
+  values:
+    name: api
+    image:
+      repository: api-image
+      tag: ${modules.api-image.version}
+    ingress:
+      enabled: true
+      paths: [/]
+      hosts: [api.local.app.garden]
+```
+
+Here, the `base-chart` module contains the actual Helm chart and templates. Note the `skipDeploy` flag, which we set
+because the module should only be used as a base chart in this case.
+
+The `api` module only contains the `garden.yml` file, but configures the base chart using the `values` field, and also
+sets its own dependencies (those are not inherited) and specifies its `serviceResource.containerModule`.
+
+In our base chart, we make certain values like `name`, `image.repository` and `image.tag` required (using the
+[required](https://github.com/helm/helm/blob/master/docs/charts_tips_and_tricks.md#using-the-required-function)
+helper function) in order to enforce correct usage. We recommend enforcing constraints like that, so that mistakes
+can be caught quickly.
+
+The `result` module also uses the same base chart, but sets different values and metadata:
+
+```yaml
+module:
+  description: Helm chart for the results UI
+  type: helm
+  name: result
+  base: base-chart
+  serviceResource:
+    containerModule: result-image
+    hotReloadArgs: [nodemon, server.js]
+  dependencies:
+    - db-init
+  values:
+    name: result
+    image:
+      repository: result-image
+      tag: ${modules.result-image.version}
+    ingress:
+      enabled: true
+      paths: [/]
+      hosts: [result.local.app.garden]
+  tests:
+    - name: integ
+      args: [echo, ok]
+      dependencies:
+        - db-init
+```
+
+This pattern can be quite powerful, and can be used to share common templates across your organization. You could
+even have an organization-wide repository of base charts for different purposes, and link it in your project config
+with something like this:
+
+```yaml
+project:
+  sources:
+    - name: base-charts
+      repositoryUrl: https://github.com/my-org/helm-base-charts.git#v0.1.0
+  ...
+```
+
+The base chart can also be any `helm` module (not just "base" charts specifically made for that purpose), so you have
+a lot of flexibility in how you organize your charts.

examples/vote-helm/README.md

@@ -1,13 +1,19 @@
 # Voting example project with Helm charts
 
 This is a clone of the [vote example project](../vote/README.md), modified to use Helm charts to describe
-Kubernetes resources, instead of the `container` module type.
+Kubernetes resources, instead of the simpler `container` module type.
 
 You'll notice that we still use the `container` module types for building the container images (the corresponding
 `*-image` next to each service module), but they do not contain a `service` section.
 
 The `helm` modules only contain the charts, which reference the container images. Garden will build the images
 ahead of deploying the charts.
 
+Furthermore, to showcase the chart re-use feature, the `api` and `result` modules use the `base-chart` module
+as a base.
+
+For more details on how to use Helm charts, please refer to our
+[Helm user guide](https://docs.garden.io/using-garden).
+
 The usage and workflow is the same as in the [vote project](../vote/README.md), please refer to that for usage
 instructions.

examples/vote-helm/api/garden.yml

@@ -2,13 +2,15 @@ module:
   description: The API backend for the voting UI
   type: helm
   name: api
+  base: base-chart
   serviceResource:
-    kind: Deployment
     containerModule: api-image
   dependencies:
     - redis
   values:
+    name: api
     image:
+      repository: api-image
       tag: ${modules.api-image.version}
     ingress:
       enabled: true

examples/vote-helm/api/Chart.yaml → examples/vote-helm/base-chart/Chart.yaml

@@ -1,5 +1,5 @@
 apiVersion: v1
 appVersion: "1.0"
 description: A Helm chart for Kubernetes
-name: api
+name: base-chart
 version: 0.1.0

examples/vote-helm/base-chart/garden.yml

@@ -0,0 +1,7 @@
+module:
+  description: Base Helm chart for services
+  type: helm
+  name: base-chart
+  serviceResource:
+    kind: Deployment
+  skipDeploy: true

examples/vote-helm/api/templates/NOTES.txt → examples/vote-helm/base-chart/templates/NOTES.txt

@@ -6,16 +6,16 @@
   {{- end }}
 {{- end }}
 {{- else if contains "NodePort" .Values.service.type }}
-  export NODE_PORT=$(kubectl get --namespace {{ .Release.Namespace }} -o jsonpath="{.spec.ports[0].nodePort}" services {{ include "api.fullname" . }})
+  export NODE_PORT=$(kubectl get --namespace {{ .Release.Namespace }} -o jsonpath="{.spec.ports[0].nodePort}" services {{ include "base-chart.fullname" . }})
   export NODE_IP=$(kubectl get nodes --namespace {{ .Release.Namespace }} -o jsonpath="{.items[0].status.addresses[0].address}")
   echo http://$NODE_IP:$NODE_PORT
 {{- else if contains "LoadBalancer" .Values.service.type }}
      NOTE: It may take a few minutes for the LoadBalancer IP to be available.
-           You can watch the status of by running 'kubectl get svc -w {{ include "api.fullname" . }}'
-  export SERVICE_IP=$(kubectl get svc --namespace {{ .Release.Namespace }} {{ include "api.fullname" . }} -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+           You can watch the status of by running 'kubectl get svc -w {{ include "base-chart.fullname" . }}'
+  export SERVICE_IP=$(kubectl get svc --namespace {{ .Release.Namespace }} {{ include "base-chart.fullname" . }} -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
   echo http://$SERVICE_IP:{{ .Values.service.port }}
 {{- else if contains "ClusterIP" .Values.service.type }}
-  export POD_NAME=$(kubectl get pods --namespace {{ .Release.Namespace }} -l "app.kubernetes.io/name={{ include "api.name" . }},app.kubernetes.io/instance={{ .Release.Name }}" -o jsonpath="{.items[0].metadata.name}")
+  export POD_NAME=$(kubectl get pods --namespace {{ .Release.Namespace }} -l "app.kubernetes.io/name={{ include "base-chart.name" . }},app.kubernetes.io/instance={{ .Release.Name }}" -o jsonpath="{.items[0].metadata.name}")
   echo "Visit http://127.0.0.1:8080 to use your application"
   kubectl port-forward $POD_NAME 8080:80
 {{- end }}