fix!: fallback to sh if bash does not exist

It is a breaking change because it changes how the shell is
determined.

Before, if `jobs.<job_id>.container.image` is set and the shell is not
specified, it defaults to `sh` instead of `bash`.

After, regardless of `jobs.<job_id>.container.image`, if the shell is
not specified, it defaults to `bash` if available, otherwise it
defaults to `sh`.

Rework the shell integration tests:

- Remove container specific tests because the special behavior related
  to shell being set differently when a container image is present is
  removed
- Modify the defaults test case to verify the fallback logic
- Use container images from code.forgejo.org to escape rate limiting
  in the CI
- Add the missing node test
- Use
      container:
        image: code.forgejo.org/oci/node:22-bookworm
  instead of
      container: code.forgejo.org/oci/node:22-bookworm
  because it silently failed to run (with no exit code)
- Prefer `-z "${BASH}"` because `-z ${BASH+x}` reads obscure

Closes forgejo/runner#150

act/runner/run_context.go

@@ -12,11 +12,13 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path"
 	"path/filepath"
 	"regexp"
 	"runtime"
 	"strings"
 	"text/template"
+	"time"
 
 	"github.com/docker/docker/api/types/network"
 	"github.com/docker/go-connections/nat"
@@ -585,6 +587,42 @@ func (rc *RunContext) startJobContainer() common.Executor {
 	}
 }
 
+func (rc *RunContext) sh(ctx context.Context, script string) (stdout, stderr string, err error) {
+	timeed, cancel := context.WithTimeout(ctx, time.Minute)
+	defer cancel()
+	hout := &bytes.Buffer{}
+	herr := &bytes.Buffer{}
+
+	env := map[string]string{}
+	for k, v := range rc.Env {
+		env[k] = v
+	}
+
+	base, err := common.RandName(8)
+	if err != nil {
+		return "", "", err
+	}
+	name := base + ".sh"
+	oldStdout, oldStderr := rc.JobContainer.ReplaceLogWriter(hout, herr)
+	err = rc.JobContainer.Copy(rc.JobContainer.GetActPath(), &container.FileEntry{
+		Name: name,
+		Mode: 0o644,
+		Body: script,
+	}).
+		Then(rc.execJobContainer([]string{"sh", path.Join(rc.JobContainer.GetActPath(), name)},
+			env, "", "")).
+		Finally(func(context.Context) error {
+			rc.JobContainer.ReplaceLogWriter(oldStdout, oldStderr)
+			return nil
+		})(timeed)
+	if err != nil {
+		return "", "", err
+	}
+	stdout = hout.String()
+	stderr = herr.String()
+	return stdout, stderr, nil
+}
+
 func (rc *RunContext) execJobContainer(cmd []string, env map[string]string, user, workdir string) common.Executor {
 	return func(ctx context.Context) error {
 		return rc.JobContainer.Exec(cmd, env, user, workdir)(ctx)

act/runner/runner_test.go

@@ -227,12 +227,12 @@ func TestRunEvent(t *testing.T) {
 	tables := []TestJobFileInfo{
 		// Shells
 		{workdir, "shells/defaults", "push", "", platforms, secrets},
-		// TODO: figure out why it fails
-		// {workdir, "shells/custom", "push", "", map[string]string{"ubuntu-latest": "catthehacker/ubuntu:pwsh-latest"}, }, // custom image with pwsh
-		{workdir, "shells/pwsh", "push", "", map[string]string{"ubuntu-latest": "catthehacker/ubuntu:pwsh-latest"}, secrets}, // custom image with pwsh
+		{workdir, "shells/custom", "push", "", platforms, secrets},
 		{workdir, "shells/bash", "push", "", platforms, secrets},
-		{workdir, "shells/python", "push", "", map[string]string{"ubuntu-latest": "node:16-buster"}, secrets}, // slim doesn't have python
+		{workdir, "shells/node", "push", "", platforms, secrets},
+		{workdir, "shells/python", "push", "", platforms, secrets},
 		{workdir, "shells/sh", "push", "", platforms, secrets},
+		{workdir, "shells/pwsh", "push", "", platforms, secrets},
 
 		// Local action
 		{workdir, "local-action-docker-url", "push", "", platforms, secrets},

act/runner/step_run.go

@@ -194,9 +194,20 @@ func (sr *stepRun) setupShell(ctx context.Context) {
 			if err != nil {
 				step.Shell = shellWithFallback[1]
 			}
-		} else if containerImage := rc.containerImage(ctx); containerImage != "" {
-			// Currently only linux containers are supported, use sh by default like actions/runner
-			step.Shell = "sh"
+		} else {
+			shell_fallback := `
+if command -v bash >/dev/null; then
+	echo -n bash
+else
+	echo -n sh
+fi
+`
+			stdout, _, err := rc.sh(ctx, shell_fallback)
+			if err != nil {
+				common.Logger(ctx).Error("fail to run %q: %v", shell_fallback, err)
+				return
+			}
+			step.Shell = stdout
 		}
 	}
 }

act/runner/testdata/shells/bash/push.yml

@@ -14,7 +14,8 @@ jobs:
           fi
   check-container:
     runs-on: ubuntu-latest
-    container: node:16-buster-slim
+    container:
+      image: code.forgejo.org/oci/node:22-bookworm
     steps:
       - shell: ${{ env.MY_SHELL }}
         run: |

act/runner/testdata/shells/custom/push.yml

@@ -3,12 +3,6 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      # prints version and exits, it's not valid (for github) if {0} is not included
-      - shell: pwsh -v '. {0}'
-        run: ''
-  check-container:
-    runs-on: ubuntu-latest
-    container: catthehacker/ubuntu:pwsh-latest
-    steps:
-      - shell: pwsh -v '. {0}'
-        run: ''
+      - shell: cat {0}
+        run: |
+          exit 1

act/runner/testdata/shells/defaults/push.yml

@@ -1,6 +1,6 @@
 on: push
 jobs:
-  check: # GHA uses `bash` as default for runners
+  check: # use `bash` as default for runners
     runs-on: ubuntu-latest
     steps:
       - run: |
@@ -9,12 +9,13 @@ jobs:
           else
             exit 1
           fi
-  check-container: # GHA uses `sh` as default for containers
+  fallback: # uses `sh` as fallback default if `bash` is not available
     runs-on: ubuntu-latest
-    container: alpine:latest
+    container:
+      image: code.forgejo.org/oci/alpine:latest
     steps:
       - run: |
-          if [ -z ${BASH+x} ]; then
+          if [ -z "${BASH}" ]; then
             echo "I'm sh!"
           else
             exit 1

act/runner/testdata/shells/node/push.yml

@@ -8,13 +8,6 @@ jobs:
       - shell: ${{ env.MY_SHELL }}
         run: |
           console.log(process.version)
-  check-container:
-    runs-on: ubuntu-latest
-    container: node:16-buster-slim
-    steps:
-      - shell: ${{ env.MY_SHELL }}
-        run: |
-          console.log(process.version)
   check-job-default:
     runs-on: ubuntu-latest
     defaults:

act/runner/testdata/shells/pwsh/push.yml

@@ -4,19 +4,16 @@ env:
 jobs:
   check:
     runs-on: ubuntu-latest
-    steps:
-      - shell: ${{ env.MY_SHELL }}
-        run: |
-          $PSVersionTable
-  check-container:
-    runs-on: ubuntu-latest
-    container: catthehacker/ubuntu:pwsh-latest
+    container:
+      image: code.forgejo.org/oci/ci:1
     steps:
       - shell: ${{ env.MY_SHELL }}
         run: |
           $PSVersionTable
   check-job-default:
     runs-on: ubuntu-latest
+    container:
+      image: code.forgejo.org/oci/ci:1
     defaults:
       run:
         shell: ${{ env.MY_SHELL }}

act/runner/testdata/shells/python/push.yml

@@ -4,14 +4,8 @@ env:
 jobs:
   check:
     runs-on: ubuntu-latest
-    steps:
-      - shell: ${{ env.MY_SHELL }}
-        run: |
-          import platform
-          print(platform.python_version())
-  check-container:
-    runs-on: ubuntu-latest
-    container: node:16-buster
+    container:
+      image: code.forgejo.org/oci/python:slim
     steps:
       - shell: ${{ env.MY_SHELL }}
         run: |
@@ -19,6 +13,8 @@ jobs:
           print(platform.python_version())
   check-job-default:
     runs-on: ubuntu-latest
+    container:
+      image: code.forgejo.org/oci/python:slim
     defaults:
       run:
         shell: ${{ env.MY_SHELL }}

act/runner/testdata/shells/sh/push.yml

@@ -7,18 +7,7 @@ jobs:
     steps:
       - shell: ${{ env.MY_SHELL }}
         run: |
-          if [ -z ${BASH+x} ]; then
-            echo "I'm sh!"
-          else
-            exit 1
-          fi
-  check-container:
-    runs-on: ubuntu-latest
-    container: alpine:latest
-    steps:
-      - shell: ${{ env.MY_SHELL }}
-        run: |
-          if [ -z ${BASH+x} ]; then
+          if [ -z "${BASH}" ]; then
             echo "I'm sh!"
           else
             exit 1
@@ -30,7 +19,7 @@ jobs:
         shell: ${{ env.MY_SHELL }}
     steps:
       - run: |
-          if [ -z ${BASH+x} ]; then
+          if [ -z "${BASH}" ]; then
             echo "I'm sh!"
           else
             exit 1