feat: detects the best shell and allow to override entrypoint

index.js

@@ -34,6 +34,9 @@ const {
   GLOBAL_DEFAULT_KEY,
   DEFAULT_STAGES,
 } = require("./src/constants");
+const {
+  getShellCommandLine,
+} = require("./src/shell");
 
 // ----- globals -----
 
@@ -67,7 +70,7 @@ async function execCommands({
 
     try {
       exec = await container.exec({
-        Cmd: ["sh", "-c", command],
+        Cmd: getShellCommandLine(command),
         AttachStdout: true,
         AttachStderr: true,
         WorkingDir: workdir,
@@ -280,6 +283,9 @@ async function main() {
         (job.image?.name ? job.image.name : job.image) ??
         (DEFAULT.image?.name ? DEFAULT.image.name : DEFAULT.image) ??
         "ruby:2.5";
+      const entrypoint =
+        (job.image?.entrypoint ? job.image.entrypoint : undefined) ??
+        (DEFAULT.image?.entrypoint ? DEFAULT.image.entrypoint : undefined);
 
       let cache = {};
       if ("cache" in job) {
@@ -454,7 +460,9 @@ async function main() {
 
       const config = {
         Image: preparedImageName,
+        Entrypoint: entrypoint,
         Tty: true,
+        Cmd: getShellCommandLine(),
         Env: Object.keys(variables).map((key) => `${key}=${variables[key]}`),
         HostConfig: {
           AutoRemove: true,

src/shell.js

@@ -0,0 +1,49 @@
+// References:
+// * https://gitlab.com/gitlab-org/gitlab-runner/-/blob/master/shells/bash.go
+// * https://gitlab.com/gitlab-org/gitlab-runner/-/blob/master/executors/shell/shell.go
+
+/**
+ * get bash detect shell script
+ *
+ * @param isLoginShell {boolean} login shell
+ * @return {string} generated code
+ */
+function getBashDetectShellScript(isLoginShell) {
+  const bashDefaultArguments = isLoginShell ? '--login' : '';
+  return `if [ -x /usr/local/bin/bash ]; then
+	exec /usr/local/bin/bash ${bashDefaultArguments} "$@"
+elif [ -x /usr/bin/bash ]; then
+	exec /usr/bin/bash ${bashDefaultArguments} "$@"
+elif [ -x /bin/bash ]; then
+	exec /bin/bash ${bashDefaultArguments} "$@"
+elif [ -x /usr/local/bin/sh ]; then
+	exec /usr/local/bin/sh "$@"
+elif [ -x /usr/bin/sh ]; then
+	exec /usr/bin/sh "$@"
+elif [ -x /bin/sh ]; then
+	exec /bin/sh "$@"
+elif [ -x /busybox/sh ]; then
+	exec /busybox/sh "$@"
+else
+	echo shell not found
+	exit 1
+fi
+`;
+}
+
+function getShellCommandLine(userCommand) {
+  const command = [
+    'sh', '-c', getBashDetectShellScript(true)
+  ];
+  if (userCommand) {
+    command.push('--');
+    command.push('-c');
+    command.push(userCommand);
+  }
+  return command;
+}
+
+
+module.exports = {
+  getShellCommandLine
+};