Build args support (#22)

.github/workflows/self-test-multistage-docker-build.yml

@@ -35,6 +35,7 @@ jobs:
       - uses: ./
         id: build
         with:
+          build-args: BUILD_ARG_1=hello, BUILD_ARG_2=goodbye, version=${{ github.sha }}
           dockerfile: examples/Dockerfile
           # repository: firehed/actions
           # repository: gcr.io/firehed/actions
@@ -56,6 +57,22 @@ jobs:
             --rm
             ${{ needs.build.outputs.testenv-tag }}
             echo "I'm a test!"
+
+      - name: get build arg1
+        id: build-args
+        run: docker run
+            --rm
+            ${{ needs.build.outputs.testenv-tag }}
+            sh examples/print-outputs.sh
+
+      - name: validate build arg 1
+        if: ${{ steps.build-args.outputs.arg1 != 'hello' }}
+        run: exit 1
+
+      - name: validate build arg 2
+        if: ${{ steps.build-args.outputs.arg2 != 'goodbye' }}
+        run: exit 1
+
       - name: display server
         run: echo ${{ needs.build.outputs.server-tag }}
 

README.md

@@ -20,6 +20,7 @@ While the initial build will, of course, be performed from scratch, subsequent b
 | `testenv-stage` | no | | Name of stage for test environment |
 | `dockerfile` | no | `Dockerfile` | Path to the Dockerfile |
 | `quiet` | no | `true` | Should docker commands be passed `--quiet` |
+| `build-args` | no | | Comma-separated list of `--build-arg` flags. |
 
 ## Outputs
 
@@ -69,6 +70,7 @@ jobs:
           stages: env, configured
           testenv-stage: testenv
           server-stage: server
+          build-args: arg1=val1, arg2=val2
 
       # This assumes your testenv actually runs the tests, and
       # exits 0 if they all pass and nonzero on failure

action.yml

@@ -5,6 +5,10 @@ author: Eric Stern
 description: Build Docker images to maximize layer caching and minimize build times
 
 inputs:
+  build-args:
+    description: A comma-separated list of `--build-arg` flags
+    required: false
+    default: ''
   dockerfile:
     description: Path to Dockerfile
     required: false

examples/Dockerfile

@@ -10,7 +10,11 @@ COPY . .
 CMD ls
 
 FROM configured AS testenv
+ARG BUILD_ARG_1
+ARG BUILD_ARG_2
 RUN apk add --update --no-cache libzip-dev
+RUN echo ${BUILD_ARG_1} > build_arg_1.txt
+RUN echo ${BUILD_ARG_2} > build_arg_2.txt
 COPY . .
 RUN echo bar > bar.txt
 CMD ls

examples/print-outputs.sh

@@ -0,0 +1,2 @@
+echo "::set-output name=arg1::$(cat build_arg_1.txt)"
+echo "::set-output name=arg2::$(cat build_arg_2.txt)"

src/helpers.ts

@@ -43,6 +43,13 @@ export function getBaseStages(): string[] {
     .filter(stage => stage !== '')
 }
 
+export function getBuildArgs(): string[] {
+  return core.getInput('build-args')
+    .split(',')
+    .map(arg => arg.trim())
+    .filter(arg => arg !== '')
+}
+
 export function getAllStages(): string[] {
   const stages = [
     ...getBaseStages(),

src/index.ts

@@ -4,6 +4,7 @@ import {
   isDefaultBranch,
   getFullCommitHash,
   getTagForRun,
+  getBuildArgs,
   getBaseStages,
   getAllStages,
   getTaggedImageForStage,
@@ -95,11 +96,15 @@ async function buildStage(stage: string, extraTags: string[]): Promise<string> {
     const targetTag = getTaggedImageForStage(stage, getTagForRun())
 
     const cacheFromArg = getAllPossibleCacheTargets()
-    .flatMap(target => ['--cache-from', target])
+      .flatMap(target => ['--cache-from', target])
+
+    const buildArgs = getBuildArgs()
+      .flatMap(arg => ['--build-arg', arg])
 
     const result = await runDockerCommand(
       'build',
       // '--build-arg', 'BUILDKIT_INLINE_CACHE="1"',
+      ...buildArgs,
       ...cacheFromArg,
       '--file', dockerfile,
       '--tag', targetTag,