Merge pull request #941 from gabemontero/deprecate-implicit-emptydir

SHIP-22: add deprecation notice for implicit tekton workspace emptydir volumes

deploy/crds/shipwright.io_buildstrategies.yaml

@@ -37,7 +37,7 @@ spec:
             properties:
               buildSteps:
                 items:
-                  description: BuildStep defines a partial step that needs to run in container for building the image.
+                  description: BuildStep defines a partial step that needs to run in container for building the image. If the build step declares a volumeMount, Shipwright will create an emptyDir volume mount for the named volume. Build steps which share the same named volume in the volumeMount will share the same underlying emptyDir volume. This behavior is deprecated, and will be removed when full volume support is added to build strategies as specified in SHIP-0022.
                   properties:
                     args:
                       description: 'Arguments to the entrypoint. The docker image''s CMD is used if this is not provided. Variable references $(VAR_NAME) are expanded using the container''s environment. If a variable cannot be resolved, the reference in the input string will be unchanged. The $(VAR_NAME) syntax can be escaped with a double $$, ie: $$(VAR_NAME). Escaped references will never be expanded, regardless of whether the variable exists or not. Cannot be updated. More info: https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell'

deploy/crds/shipwright.io_clusterbuildstrategies.yaml

@@ -37,7 +37,7 @@ spec:
             properties:
               buildSteps:
                 items:
-                  description: BuildStep defines a partial step that needs to run in container for building the image.
+                  description: BuildStep defines a partial step that needs to run in container for building the image. If the build step declares a volumeMount, Shipwright will create an emptyDir volume mount for the named volume. Build steps which share the same named volume in the volumeMount will share the same underlying emptyDir volume. This behavior is deprecated, and will be removed when full volume support is added to build strategies as specified in SHIP-0022.
                   properties:
                     args:
                       description: 'Arguments to the entrypoint. The docker image''s CMD is used if this is not provided. Variable references $(VAR_NAME) are expanded using the container''s environment. If a variable cannot be resolved, the reference in the input string will be unchanged. The $(VAR_NAME) syntax can be escaped with a double $$, ie: $$(VAR_NAME). Escaped references will never be expanded, regardless of whether the variable exists or not. Cannot be updated. More info: https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell'

docs/buildstrategies.md

@@ -634,3 +634,12 @@ The following annotations are not propagated:
 - `buildrun.shipwright.io/*`
 
 A Kubernetes administrator can further restrict the usage of annotations by using policy engines like [Open Policy Agent](https://www.openpolicyagent.org/).
+
+## Volumes and VolumeMounts
+
+Build steps can declare a `volumeMount`, which allows data in the provided path to be shared across build steps.
+When a `volumeMount` is declared, Shipwright will create an `emptyDir` volume with the corresponding name.
+Build steps whose volume mounts share the same name will share the same underlying `emtpyDir` volume.
+
+In a future release, build strategy authors will be able to use other volume types for the volume mounts.
+When this feature is introduced, the volume and volume type will need to be explicitly declared.

pkg/apis/build/v1alpha1/buildstrategy.go

@@ -41,8 +41,11 @@ type Parameter struct {
 	Default *string `json:"default"`
 }
 
-// BuildStep defines a partial step that needs to run in container for
-// building the image.
+// BuildStep defines a partial step that needs to run in container for building the image.
+// If the build step declares a volumeMount, Shipwright will create an emptyDir volume mount for the named volume.
+// Build steps which share the same named volume in the volumeMount will share the same underlying emptyDir volume.
+// This behavior is deprecated, and will be removed when full volume support is added to build strategies as specified
+// in SHIP-0022. 
 type BuildStep struct {
 	corev1.Container `json:",inline"`
 }