Fix #83: Add support for custom shell

jacob-carlborg · jacob-carlborg · commit 566b34e1d6c3 · 2026-01-04T19:00:49.000+01:00
This allows to specify the shell as `cpa.sh {0}` and then use the
regular `run` syntax to run commands inside the VM.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -548,3 +548,45 @@ jobs:
           sync_files: false
           shutdown_vm: false
           run: true
+
+  shell-mode:
+    timeout-minutes: 5
+    name: Test running the action in shell mode
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: cpa.sh {0}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - shell: bash
+        run: |
+          sudo apt update
+          sudo apt install -y dosfstools rsync fdisk
+
+      - name: Start VM
+        uses: ./
+        with:
+          operating_system: freebsd
+          architecture: x86-64
+          version: '15.0'
+          hypervisor: qemu
+          shutdown_vm: false
+          run: echo "Starting VM"
+
+      - name: Verify VM configuration
+        run: |
+          uname -a
+          [ "$(uname)" = "FreeBSD" ]
+          [ "$(uname -r | cut -d- -f1)" = "15.0" ]
+          [ "$(uname -m)" = "amd64" ]
+
+      - name: Create file in VM
+        run: touch shell_mode_test.txt
+
+      - name: Check file in subsequent step
+        run: test -f shell_mode_test.txt
diff --git a/action.yml b/action.yml
@@ -3,19 +3,19 @@ description: Provides cross platform runner
 author: Jacob Carlborg
 inputs:
   run:
-    required: true
+    required: false
     description: |
       Runs command-line programs using the operating system's shell.
       This will be executed inside the virtual machine.
   operating_system:
-    required: true
+    required: false
     description: The type of operating system to run the job on
   architecture:
     required: false
     description: The architecture of the operating system.
     default: x86-64
   version:
-    required: true
+    required: false
     description: The version of the operating system to use
   shell:
     required: false
@@ -57,7 +57,6 @@ inputs:
     required: false
     description: |
       Specifies if the VM should be shutdown after the action has been run.
-    default: true
 
 runs:
   using: node20
diff --git a/changelog.md b/changelog.md
@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Add support for running the action as a custom shell ([#23](https://github.com/cross-platform-actions/action/issues/23)).
+    This allows to run multiple steps in the same job without having to invoke
+    the action multiple times.
 
 ## [0.32.0] - 2025-12-21
 ### Added
diff --git a/cpa.sh b/cpa.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+export INPUT_RUN="$(cat $1)"
+export CPA_SHELL_MODE=true
+
+node "$GITHUB_ACTION_PATH/dist/index.js"
diff --git a/dist/index.js b/dist/index.js
diff --git a/dist/index.js.map b/dist/index.js.map
diff --git a/readme.md b/readme.md
@@ -13,7 +13,7 @@ Some of the features that this action supports include:
 - Allows to use default shell or Bash shell
 - Low boot overhead
 - Fast execution
-- Using the action in multiple steps in the same job
+- Using the action in multiple steps in the same job by using a custom shell
 
 ## `Usage`
 
@@ -61,6 +61,9 @@ on: [push]
 jobs:
   test:
     runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: cpa.sh {0}
     strategy:
       matrix:
         os:
@@ -108,13 +111,14 @@ jobs:
           shell: bash
           memory: 5G
           cpu_count: 4
-          run: |
-            uname -a
-            echo $SHELL
-            pwd
-            ls -lah
-            whoami
-            env | sort
+
+      - run: |
+          uname -a
+          echo $SHELL
+          pwd
+          ls -lah
+          whoami
+          env | sort
 ```
 
 Different platforms need to run on different runners, so see the
diff --git a/src/action/action.ts b/src/action/action.ts
@@ -55,7 +55,9 @@ export class Action {
   async run(): Promise<void> {
     core.startGroup('Setting up VM')
     core.debug('Running action')
+
     const runPreparer = this.createRunPreparer()
+    runPreparer.setupEnvironment()
     runPreparer.createInputHash()
     runPreparer.validateInputHash()
 
@@ -106,7 +108,9 @@ export class Action {
       core.info('VM is ready')
       try {
         core.endGroup()
-        await this.runCommand(vm)
+        if (this.input.hasRun) {
+          await this.runCommand(vm)
+        }
       } finally {
         core.startGroup('Tearing down VM')
         await vm.synchronizeBack()
@@ -239,9 +243,14 @@ export class Action {
   }
 
   private createRunPreparer(): RunPreparer {
-    const cls = runPreparerFor({isRunning: vmModule.Vm.isRunning})
+    const isRunning = vmModule.Vm.isRunning
+    const cls = runPreparerFor({isRunning})
+    const environmentSetup = environmentSetupFor({
+      isRunning,
+      isShellMode: process.env['CPA_SHELL_MODE'] === 'true'
+    })
     core.debug(`Using run preparer: ${cls.name}`)
-    return new cls(this, this.operatingSystem)
+    return new cls(this, this.operatingSystem, environmentSetup)
   }
 }
 
@@ -261,7 +270,45 @@ function runPreparerFor({
   return isRunning ? LiveRunPreparer : InitialRunPreparer
 }
 
+function environmentSetupFor({
+  isRunning,
+  isShellMode
+}: {
+  isRunning: boolean
+  isShellMode: boolean
+}): EnvironmentSetup {
+  if (isShellMode) return new ShellEnvironmentSetup()
+  return isRunning ? new LiveEnvironmentSetup() : new InitialEnvironmentSetup()
+}
+
+interface EnvironmentSetup {
+  setup(): void
+}
+
+class ShellEnvironmentSetup implements EnvironmentSetup {
+  setup(): void {
+    // noop
+  }
+}
+
+class InitialEnvironmentSetup implements EnvironmentSetup {
+  setup(): void {
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    core.addPath(process.env['GITHUB_ACTION_PATH']!)
+  }
+}
+
+class LiveEnvironmentSetup implements EnvironmentSetup {
+  setup(): void {
+    core.warning(
+      'Invoking the action multiple times is deprecated. Please use the ' +
+        'shell integration instead.'
+    )
+  }
+}
+
 interface RunPreparer {
+  setupEnvironment(): void
   createInputHash(): void
   validateInputHash(): void
   download(): [Promise<string>, Promise<string>, Promise<string>]
@@ -276,10 +323,20 @@ interface RunPreparer {
 class InitialRunPreparer implements RunPreparer {
   private readonly action: Action
   private readonly operatingSystem: os.OperatingSystem
+  private readonly environmentSetup: EnvironmentSetup
 
-  constructor(action: Action, operatingSystem: os.OperatingSystem) {
+  constructor(
+    action: Action,
+    operatingSystem: os.OperatingSystem,
+    environmentSetup: EnvironmentSetup
+  ) {
     this.action = action
     this.operatingSystem = operatingSystem
+    this.environmentSetup = environmentSetup
+  }
+
+  setupEnvironment(): void {
+    this.environmentSetup.setup()
   }
 
   createInputHash(): void {
@@ -318,9 +375,19 @@ class InitialRunPreparer implements RunPreparer {
 // Used when the VM is already running
 class LiveRunPreparer implements RunPreparer {
   private readonly action: Action
+  private readonly environmentSetup: EnvironmentSetup
 
-  constructor(action: Action) {
+  constructor(
+    action: Action,
+    _operatingSystem: os.OperatingSystem,
+    environmentSetup: EnvironmentSetup
+  ) {
     this.action = action
+    this.environmentSetup = environmentSetup
+  }
+
+  setupEnvironment(): void {
+    this.environmentSetup.setup()
   }
 
   createInputHash(): void {
diff --git a/src/action/input.ts b/src/action/input.ts
