Rename 'archs' input and improve multiarch

Expand readme
Add example

Signed-off-by: Tim Etchells <tetchel@gmail.com>

.github/workflows/multiarch.yml

@@ -0,0 +1,71 @@
+name: Multiarch build
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 0 * * *'  # every day at midnight
+
+env:
+  IMAGE_NAME: hello-world-multiarch
+  IMAGE_TAG: latest
+
+jobs:
+  build:
+    name: Build image using Buildah
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+        arch: [ amd64, i386, arm64v8 ]
+    steps:
+
+      # Checkout buildah action github repository
+      - name: Checkout Buildah action
+        uses: actions/checkout@v2
+        with:
+          path: "buildah-build"
+
+      - name: Install qemu dependency
+        run: sudo apt-get install -y qemu-user-static
+
+      - name: Create Dockerfile
+        run: |
+          cat > Dockerfile<<EOF
+
+          ARG ARCH
+          FROM docker.io/\${ARCH}/alpine:3.14
+
+          RUN echo "hello world"
+
+          ENTRYPOINT [ "sh", "-c", "echo -n 'Machine: ' && uname -m && echo -n 'Bits: ' && getconf LONG_BIT && echo 'goodbye world'" ]
+          EOF
+
+      - name: Build Image
+        id: build_image
+        uses: ./buildah-build/
+        with:
+          image: ${{ env.IMAGE_NAME }}
+          tags: ${{ env.IMAGE_TAG }}
+          arch: ${{ matrix.arch }}
+          build-args: ARCH=${{ matrix.arch }}
+          dockerfiles: |
+            ./Dockerfile
+
+      - name: Echo Outputs
+        run: |
+          echo "Image: ${{ steps.build_image.outputs.image }}"
+          echo "Tags: ${{ steps.build_image.outputs.tags }}"
+
+      - name: Check images created
+        run: buildah images | grep '${{ env.IMAGE_NAME }}'
+
+      - name: Check image metadata
+        run: |
+          set -x
+          buildah inspect ${{ steps.build_image.outputs.image }}:${{ env.IMAGE_TAG }} | jq ".OCIv1.architecture"
+          buildah inspect ${{ steps.build_image.outputs.image }}:${{ env.IMAGE_TAG }} | jq ".Docker.architecture"
+
+      - name: Run image
+        run: |
+          podman run --rm ${{ steps.build_image.outputs.image }}:${{ env.IMAGE_TAG }}

.github/workflows/scratch_build.yml

@@ -84,7 +84,7 @@ jobs:
             -jar
             spring-petclinic-*.jar
           port: 8080
-          archs: amd64,arm64
+          arch: amd64
           workdir: "."
 
       - name: Echo Outputs

README.md

@@ -25,7 +25,7 @@ After building your image, use [push-to-registry](https://github.com/redhat-acti
 
 | Input Name | Description | Default |
 | ---------- | ----------- | ------- |
-| archs | Architecture(s) to build the image(s) for. For multiple architectures, separate by a comma. Refer to [Multi arch builds](#multi-arch-builds) to setup the `qemu-user-static` dependency. | None (host architecture)
+| arch | Label the image with this ARCH, instead of defaulting to the host architecture. Refer to [Multi arch builds](#multi-arch-builds) to setup the `qemu-user-static` dependency. | None (host architecture)
 | build-args | Build arguments to pass to the Docker build using `--build-arg`, if using a Dockerfile that requires ARGs. Use the form `arg_name=arg_value`, and separate arguments with newlines. | None
 | context | Path to directory to use as the build context. | `.`
 | dockerfiles | The list of Dockerfile paths to perform a build using docker instructions. This is a multiline input to allow multiple Dockerfiles. | **Must be provided**
@@ -41,7 +41,7 @@ After building your image, use [push-to-registry](https://github.com/redhat-acti
 
 | Input Name | Description | Default |
 | ---------- | ----------- | ------- |
-| archs | Architecture(s) to build the image(s) for. For multiple architectures, separate by a comma. | None (host architecture)
+| arch | Label the image with this ARCH, instead of defaulting to the host architecture. | None (host architecture)
 | base-image | The base image to use for the container. | **Must be provided**
 | content | Paths to files or directories to copy inside the container to create the file image. This is a multiline input to allow you to copy multiple files/directories.| None
 | entrypoint | The entry point to set for the container. This is a multiline input; split arguments across lines. | None
@@ -146,11 +146,31 @@ jobs:
 
 ## Multi arch builds
 
-Cross-architecture builds from dockerfiles containing `RUN` instructions require `qemu-user-static` emulation registered in the Linux kernel. Run `sudo apt install -y qemu-user-static` on Debian-based container hosts. Or run the following registration command for other distributions:
-```
+Refer to the [multi-arch example](./.github/workflows/multiarch.yml).
+
+### Emulating RUN instructions
+
+Cross-architecture builds from dockerfiles containing `RUN` instructions require `qemu-user-static` emulation registered in the Linux kernel.
+
+For example, run `sudo apt install qemu-user-static` on Debian hosts, or `sudo dnf install qemu-user-static` on Fedora.
+
+You can run a [containerized version of the registration](https://hub.docker.com/r/tonistiigi/binfmt) if the package does not exist for your distribution:
+```sh
 sudo podman run --rm --privileged docker.io/tonistiigi/binfmt --install all
 ```
-The registration remains active until the container host reboots.
+This registration remains active until the host reboots.
+
+### The `arch` input
+The `arch` argument overrides the `ARCH` label in the output image. It does not actually affect the architectures the output image will run on. The image must still be built for the required architecture.
+
+There is a simple example [in this issue](https://github.com/redhat-actions/buildah-build/issues/60#issuecomment-876552452).
+
+### Creating a Multi-Arch Image List
+Use the [buildah manifest](https://github.com/containers/buildah/blob/main/docs/buildah-manifest.md) command to bundle images into an image list, so multiple image can be referenced by the same repository tag.
+
+There are examples and explanations of the `manifest` command [in this issue](https://github.com/containers/buildah/issues/1590).
+
+This action does not support the `manifest` command at this time, but there is [an issue open](https://github.com/redhat-actions/buildah-build/issues/61).
 
 ## Using private images
 

action.yml

@@ -47,11 +47,11 @@ inputs:
     description: 'Set to true to build using the OCI image format instead of the Docker image format'
     default: 'false'
     required: false
+  arch:
+    description: 'Label the image with this ARCH, instead of defaulting to the host architecture.'
+    required: false
   archs:
-    description: |
-      Architecture(s) to build the image(s) for. For multiple architectures,
-      separate by a comma.
-    default: 'amd64'
+    description: 'Alias for "arch". "arch" takes precedence if both are set.'
     required: false
   extra-args:
     description: |

package.json

@@ -23,19 +23,18 @@
     "@actions/core": "^1.2.6",
     "@actions/exec": "^1.0.4",
     "@actions/io": "^1.0.2",
-    "ini": "^2.0.0",
-    "language-recognizer": "0.0.1"
+    "ini": "^2.0.0"
   },
   "devDependencies": {
     "@redhat-actions/action-io-generator": "^1.5.0",
-    "@redhat-actions/eslint-config": "^1.2.11",
+    "@redhat-actions/eslint-config": "^1.3.2",
     "@redhat-actions/tsconfig": "^1.1.1",
     "@types/ini": "^1.3.30",
     "@types/node": "^12",
-    "@typescript-eslint/eslint-plugin": "^4.14.1",
-    "@typescript-eslint/parser": "^4.14.1",
+    "@typescript-eslint/eslint-plugin": "^4.28.2",
+    "@typescript-eslint/parser": "^4.28.2",
     "@vercel/ncc": "^0.25.1",
-    "eslint": "^7.18.0",
-    "typescript": "^4.0.5"
+    "eslint": "^7.30.0",
+    "typescript": "^4.3.5"
   }
 }

src/buildah.ts

@@ -14,13 +14,13 @@ export interface BuildahConfigSettings {
     envs?: string[];
     port?: string;
     workingdir?: string;
-    archs?: string;
+    arch?: string;
 }
 
 interface Buildah {
     buildUsingDocker(
         image: string, context: string, dockerFiles: string[], buildArgs: string[],
-        useOCI: boolean, archs: string, layers: string, extraArgs: string[]
+        useOCI: boolean, arch: string, layers: string, extraArgs: string[]
     ): Promise<CommandResult>;
     from(baseImage: string): Promise<CommandResult>;
     copy(container: string, contentToCopy: string[]): Promise<CommandResult | undefined>;
@@ -63,12 +63,12 @@ export class BuildahCli implements Buildah {
 
     async buildUsingDocker(
         image: string, context: string, dockerFiles: string[], buildArgs: string[],
-        useOCI: boolean, archs: string, layers: string, extraArgs: string[]
+        useOCI: boolean, arch: string, layers: string, extraArgs: string[]
     ): Promise<CommandResult> {
         const args: string[] = [ "bud" ];
-        if (archs) {
+        if (arch) {
             args.push("--arch");
-            args.push(archs);
+            args.push(arch);
         }
         dockerFiles.forEach((file) => {
             args.push("-f");
@@ -131,9 +131,9 @@ export class BuildahCli implements Buildah {
                 args.push(env);
             });
         }
-        if (settings.archs) {
+        if (settings.arch) {
             args.push("--arch");
-            args.push(settings.archs);
+            args.push(settings.arch);
         }
         if (settings.workingdir) {
             args.push("--workingdir");

src/generated/inputs-outputs.ts

@@ -1,10 +1,15 @@
 // This file was auto-generated by action-io-generator. Do not edit by hand!
 export enum Inputs {
     /**
-     * Architecture(s) to build the image(s) for. For multiple architectures,
-     * separate by a comma.
+     * Label the image with this ARCH, instead of defaulting to the host architecture.
      * Required: false
-     * Default: "amd64"
+     * Default: None.
+     */
+    ARCH = "arch",
+    /**
+     * Alias for "arch". "arch" takes precedence if both are set.
+     * Required: false
+     * Default: None.
      */
     ARCHS = "archs",
     /**

src/index.ts

@@ -33,21 +33,20 @@ export async function run(): Promise<void> {
     const tagsList: string[] = tags.split(" ");
 
     // info message if user doesn't provides any tag
-    if (!tagsList.length) {
+    if (tagsList.length === 0) {
         core.info(`Input "${Inputs.TAGS}" is not provided, using default tag "${DEFAULT_TAG}"`);
         tagsList.push(DEFAULT_TAG);
     }
     const newImage = `${image}:${tagsList[0]}`;
     const useOCI = core.getInput(Inputs.OCI) === "true";
-    let archs: string | undefined = core.getInput(Inputs.ARCHS);
-    // remove white spaces (if any) in archs input
-    archs = archs.replace(/\s+/g, "");
+
+    const arch = getArch();
 
     if (dockerFiles.length !== 0) {
-        await doBuildUsingDockerFiles(cli, newImage, workspace, dockerFiles, useOCI, archs);
+        await doBuildUsingDockerFiles(cli, newImage, workspace, dockerFiles, useOCI, arch);
     }
     else {
-        await doBuildFromScratch(cli, newImage, useOCI, archs);
+        await doBuildFromScratch(cli, newImage, useOCI, arch);
     }
 
     if (tagsList.length > 1) {
@@ -58,7 +57,7 @@ export async function run(): Promise<void> {
 }
 
 async function doBuildUsingDockerFiles(
-    cli: BuildahCli, newImage: string, workspace: string, dockerFiles: string[], useOCI: boolean, archs: string
+    cli: BuildahCli, newImage: string, workspace: string, dockerFiles: string[], useOCI: boolean, arch: string
 ): Promise<void> {
     if (dockerFiles.length === 1) {
         core.info(`Performing build from Dockerfile`);
@@ -81,12 +80,12 @@ async function doBuildUsingDockerFiles(
         buildahBudExtraArgs = lines.flatMap((line) => line.split(" ")).map((arg) => arg.trim());
     }
     await cli.buildUsingDocker(
-        newImage, context, dockerFileAbsPaths, buildArgs, useOCI, archs, layers, buildahBudExtraArgs
+        newImage, context, dockerFileAbsPaths, buildArgs, useOCI, arch, layers, buildahBudExtraArgs
     );
 }
 
 async function doBuildFromScratch(
-    cli: BuildahCli, newImage: string, useOCI: boolean, archs: string
+    cli: BuildahCli, newImage: string, useOCI: boolean, arch: string
 ): Promise<void> {
     core.info(`Performing build from scratch`);
 
@@ -107,7 +106,7 @@ async function doBuildFromScratch(
         port,
         workingdir: workingDir,
         envs,
-        archs,
+        arch,
     };
     await cli.config(containerId, newImageConfig);
     await cli.commit(containerId, newImage, useOCI);
@@ -127,4 +126,19 @@ function getInputList(name: string): string[] {
         );
 }
 
+function getArch(): string {
+    // 'arch' should be used over 'archs', see https://github.com/redhat-actions/buildah-build/issues/60
+    const archs = core.getInput(Inputs.ARCHS).replace(/\s+/g, "");
+    const arch = core.getInput(Inputs.ARCH).replace(/\s+/g, "");
+
+    if (arch && archs) {
+        core.warning(
+            `Please use only one input of "${Inputs.ARCH}" and "${Inputs.ARCHS}". "${Inputs.ARCH}" takes precedence, `
+            + `so --arch argument will be "${arch}".`
+        );
+    }
+
+    return arch || archs;
+}
+
 run().catch(core.setFailed);