Output available platforms for setup-qemu

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/setup-qemu-ci.yml

@@ -38,7 +38,11 @@ jobs:
         uses: actions/checkout@v2.3.1
       -
         name: Set up QEMU
+        id: qemu
         uses: ./setup-qemu/
         with:
           image: ${{ matrix.image }}
           platforms: ${{ matrix.platforms }}
+      -
+        name: Available platforms
+        run: echo ${{ steps.qemu.outputs.platforms }}

setup-qemu/README.md

@@ -30,10 +30,14 @@ jobs:
         uses: actions/checkout@v2
       -
         name: Set up QEMU
+        id: qemu
         uses: docker/actions/setup-qemu@v1
         with:
           image: tonistiigi/binfmt:latest
           platforms: all
+      -
+        name: Available platforms
+        run: echo ${{ steps.qemu.outputs.platforms }}
 ```
 
 ## Customizing
@@ -47,6 +51,14 @@ Following inputs can be used as `step.with` keys
 | `image`          | String  | `tonistiigi/binfmt:latest`  | QEMU static binaries Docker image. Example: [`tonistiigi/binfmt:latest`](https://hub.docker.com/r/tonistiigi/binfmt/tags) |
 | `platforms`      | String  | `all`                       | Platforms to install. Example: `arm64,riscv64,arm` |
 
+### outputs
+
+Following outputs are available
+
+| Name          | Type    | Description                           |
+|---------------|---------|---------------------------------------|
+| `platforms`   | String  | Available platforms (comma separated) |
+
 ## Limitation
 
 This action is only available for Linux [virtual environments](https://help.github.com/en/articles/virtual-environments-for-github-actions#supported-virtual-environments-and-hardware-resources).

setup-qemu/action.yml

@@ -16,6 +16,10 @@ inputs:
     default: 'all'
     required: false
 
+outputs:
+  platforms:
+    description: 'Available platforms (comma separated)'
+
 runs:
   using: 'node12'
   main: 'dist/index.js'

setup-qemu/src/exec.ts

@@ -0,0 +1,34 @@
+import * as actionsExec from '@actions/exec';
+import {ExecOptions} from '@actions/exec';
+
+export interface ExecResult {
+  success: boolean;
+  stdout: string;
+  stderr: string;
+}
+
+export const exec = async (command: string, args: string[] = [], silent: boolean): Promise<ExecResult> => {
+  let stdout: string = '';
+  let stderr: string = '';
+
+  const options: ExecOptions = {
+    silent: silent,
+    ignoreReturnCode: true
+  };
+  options.listeners = {
+    stdout: (data: Buffer) => {
+      stdout += data.toString();
+    },
+    stderr: (data: Buffer) => {
+      stderr += data.toString();
+    }
+  };
+
+  const returnCode: number = await actionsExec.exec(command, args, options);
+
+  return {
+    success: returnCode === 0,
+    stdout: stdout.trim(),
+    stderr: stderr.trim()
+  };
+};

setup-qemu/src/main.ts

@@ -1,6 +1,11 @@
 import * as os from 'os';
 import * as core from '@actions/core';
-import * as exec from '@actions/exec';
+import * as exec from './exec';
+
+interface Platforms {
+  supported: string[];
+  available: string[];
+}
 
 async function run(): Promise<void> {
   try {
@@ -13,7 +18,15 @@ async function run(): Promise<void> {
     const platforms: string = core.getInput('platforms') || 'all';
 
     core.info(`💎 Installing QEMU static binaries...`);
-    await exec.exec('docker', ['run', '--rm', '--privileged', image, '--install', platforms]);
+    await exec.exec(`docker`, ['run', '--rm', '--privileged', image, '--install', platforms], false).then(res => {
+      if (res.stderr != '' && !res.success) {
+        throw new Error(res.stderr);
+      }
+
+      core.info('🛒 Extracting available platforms...');
+      const platforms: Platforms = JSON.parse(res.stdout.trim());
+      core.setOutput('platforms', platforms.supported.join(','));
+    });
   } catch (error) {
     core.setFailed(error.message);
   }