Merge pull request #35 from docker/add-cache-from

Add cache_froms input to support --cache-from

README.md

@@ -17,6 +17,7 @@ Suggestions and issues can be posted on the repositories [issues page](https://g
 * [target](#target)
 * [always_pull](#always_pull)
 * [build_args](#build_args)
+* [cache_froms](#cache_froms)
 * [labels](#labels)
 * [add_git_labels](#add_git_labels)
 * [push](#push)
@@ -86,11 +87,13 @@ Example:
 
 ### `path`
 
-Path to run the docker build from. Defaults to `.`.
+Path to the build context. Defaults to `.`
 
 ### `dockerfile`
 
-Name of the Dockerfile. Defaults to `{path}/Dockerfile`.
+Path to the Dockerfile. Defaults to `{path}/Dockerfile`
+
+Note when set this path is **not** relative to the `path` input but is instead relative to the current working directory.
 
 ### `target`
 
@@ -112,6 +115,15 @@ Example:
 build_args: arg1=value1,arg2=value2
 ```
 
+### `cache_froms`
+
+Comma-delimited list of images to consider as cache sources.
+
+Example:
+```yaml
+cache_froms: myorg/baseimage:latest
+```
+
 ### `labels`
 
 Comma-delimited list of labels to add to the built image.
@@ -191,3 +203,15 @@ with:
   tag_with_ref: true
   target: mytarget
 ```
+
+The following will build the root Dockerfile, tag the image as `myorg/myrepository:latest`, log in to Google Container Registry using GitHub secrets (where `DOCKER_PASSWORD` is a [JSON key](https://cloud.google.com/container-registry/docs/advanced-authentication#json-key)), and push the image to the CGR repository `myorg/myrepository`:
+ 
+```yaml
+uses: docker/build-push-action@v1
+with:
+  username: _json_key
+  password: ${{ secrets.DOCKER_PASSWORD }}
+  registry: gcr.io
+  repository: myorg/myrepository
+  tags: latest
+```

action.yml

@@ -6,7 +6,7 @@ branding:
   color: 'blue'
 runs:
   using: docker
-  image: docker://docker/github-actions:v1.0
+  image: docker://docker/github-actions:v1
   args:
     - build-push
 inputs:
@@ -34,11 +34,11 @@ inputs:
     required: false
     default: false
   path:
-    description: Path to run docker build from
+    description: Path to the build context
     required: false
     default: "."
   dockerfile:
-    description: Name of the Dockerfile (Default is 'path/Dockerfile')
+    description: Path to the Dockerfile (Default is '{path}/Dockerfile')
     required: false
   target:
     description: Sets the target stage to build
@@ -50,6 +50,9 @@ inputs:
   build_args:
     description: Comma-delimited list of build-time variables
     required: false
+  cache_froms:
+    description: Comma-delimited list of images to consider as cache sources
+    required: false
   labels:
     description: Comma-delimited list of labels to add to the built image
     required: false