Remove Image Resources

This commit removes the Image Resources support.
Removal of `pipelineResources`, as in #5967 has been broken up into removal of each resources packages for the `small PR` code standard.
This PR removes `github.com/tektoncd/pipeline/pkg/apis/resource/v1alpha1/image`
the imagedigestexporter and the docs for image resources.

cmd/controller/main.go

@@ -61,7 +61,6 @@ func main() {
 	flag.StringVar(&opts.Images.ShellImageWin, "shell-image-win", "", "The container image containing a windows shell")
 	flag.StringVar(&opts.Images.GsutilImage, "gsutil-image", "", "The container image containing gsutil")
 	flag.StringVar(&opts.Images.PRImage, "pr-image", "", "The container image containing our PR binary.")
-	flag.StringVar(&opts.Images.ImageDigestExporterImage, "imagedigest-exporter-image", "", "The container image containing our image digest exporter binary.")
 	flag.StringVar(&opts.Images.WorkingDirInitImage, "workingdirinit-image", "", "The container image containing our working dir init binary.")
 
 	// This parses flags.

config/controller.yaml

@@ -70,7 +70,6 @@ spec:
           "-entrypoint-image", "ko://github.com/tektoncd/pipeline/cmd/entrypoint",
           "-nop-image", "ko://github.com/tektoncd/pipeline/cmd/nop",
           "-sidecarlogresults-image", "ko://github.com/tektoncd/pipeline/cmd/sidecarlogresults",
-          "-imagedigest-exporter-image", "ko://github.com/tektoncd/pipeline/cmd/imagedigestexporter",
           "-pr-image", "ko://github.com/tektoncd/pipeline/cmd/pullrequest-init",
           "-workingdirinit-image", "ko://github.com/tektoncd/pipeline/cmd/workingdirinit",
 

docs/install.md

@@ -775,8 +775,6 @@ list of image references with their digest as part of the `args`:
               "gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/entrypoint:v0.28.1@sha256:2fa7f7c3408f52ff21b2d8c4271374dac4f5b113b1c4dbc7d5189131e71ce721",
               "-nop-image",
               "gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/nop:v0.28.1@sha256:59b5304bcfdd9834150a2701720cf66e3ebe6d6e4d361ae1612d9430089591f8",
-              "-imagedigest-exporter-image",
-              "gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/imagedigestexporter:v0.28.1@sha256:e4d77b5b8902270f37812f85feb70d57d6d0e1fed2f3b46f86baf534f19cd9c0",
               "-pr-image",
               "gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/pullrequest-init:v0.28.1@sha256:4992491b2714a73c0a84553030e6056e6495b3d9d5cc6b20cf7bc8c51be779bb",
 ```

docs/resources.md

@@ -47,7 +47,6 @@ For example:
 -   [Resource types](#resource-types)
     -   [Git Resource](#git-resource)
     -   [Pull Request Resource](#pull-request-resource)
-    -   [Image Resource](#image-resource)
     -   [Cluster Resource](#cluster-resource)
     -   [Storage Resource](#storage-resource)
         -   [GCS Storage Resource](#gcs-storage-resource)
@@ -581,91 +580,6 @@ spec:
       value: github
 ```
 
-### Image Resource
-
-An `image` resource represents an image that lives in a remote repository. It is
-usually used as [a `Task` `output`](tasks.md#outputs) for `Tasks` that build
-images. This allows the same `Tasks` to be used to generically push to any
-registry.
-
-Params that can be added are the following:
-
-1.  `url`: The complete path to the image, including the registry and the image
-    tag
-1.  `digest`: The
-    [image digest](https://success.docker.com/article/images-tagging-vs-digests)
-    which uniquely identifies a particular build of an image with a particular
-    tag. _While this can be provided as a parameter, there is not yet a way to
-    update this value after an image is built, but this is planned in
-    [#216](https://github.com/tektoncd/pipeline/issues/216)._
-
-For example:
-
-```yaml
-apiVersion: tekton.dev/v1alpha1
-kind: PipelineResource
-metadata:
-  name: kritis-resources-image
-  namespace: default
-spec:
-  type: image
-  params:
-    - name: url
-      value: gcr.io/staging-images/kritis
-```
-
-#### Surfacing the image digest built in a task
-
-To surface the image digest in the output of the `taskRun` the builder tool
-should produce this information in a
-[OCI Image Layout](https://github.com/opencontainers/image-spec/blob/master/image-layout.md)
-`index.json` file. This file should be placed on a location as specified in the
-task definition under the default resource directory, or the specified
-`targetPath`. If there is only one image in the `index.json` file, the digest of
-that image is exported; otherwise, the digest of the whole image index would be
-exported. For example this build-push task defines the `outputImageDir` for the
-`builtImage` resource in `/workspace/buildImage`
-
-```yaml
-apiVersion: tekton.dev/v1beta1
-kind: Task
-metadata:
-  name: build-push
-spec:
-  resources:
-    inputs:
-      - name: workspace
-        type: git
-    outputs:
-      - name: builtImage
-        type: image
-        targetPath: /workspace/builtImage
-  steps: ...
-```
-
-If no value is specified for `targetPath`, it will default to
-`/workspace/output/{resource-name}`.
-
-_Please check the builder tool used on how to pass this path to create the
-output file._
-
-The `taskRun` will include the image digest and URL in the `resourcesResult` field that
-is part of the `taskRun.Status`
-
-for example:
-
-```yaml
-status:
-    # ...
-    resourcesResult:
-      - key: "digest"
-        value: "sha256:eed29cd0b6feeb1a92bc3c4f977fd203c63b376a638731c88cacefe3adb1c660"
-        resourceName: skaffold-image-leeroy-web
-    # ...
-```
-
-If the `index.json` file is not produced, the image digest will not be included
-in the `taskRun` output.
 
 ### Cluster Resource
 

pkg/apis/pipeline/images.go

@@ -65,7 +65,6 @@ func (i Images) Validate() error {
 		{i.ShellImageWin, "shell-image-win"},
 		{i.GsutilImage, "gsutil-image"},
 		{i.PRImage, "pr-image"},
-		{i.ImageDigestExporterImage, "imagedigest-exporter-image"},
 		{i.WorkingDirInitImage, "workingdirinit-image"},
 	} {
 		if f.v == "" {