Add docs, parameterize the directory

README.md

@@ -0,0 +1,9 @@
+# GitHub Action - Synchronize Branches
+
+This GitHub Action (written in JavaScript) checks out a branch with the same name as the context (`github.ref`) branch in each repository in a directory. This helps synchronize multi-repo builds when working on related feature branches in different repositories.
+
+## Usage
+
+### Inputs
+
+- `path`: Directory containing the repositories to synchronize. Defaults to the workspace working directory.

action.yml

@@ -0,0 +1,13 @@
+name: Synchronize Branches
+description: Synchronize branches in a multi-repo build
+inputs:
+  path:
+    description: The directory containing the repositories to synchronize
+    required: true
+    default: '.'
+runs:
+  using: node12
+  main: dist/index.js
+branding:
+  icon: git-branch
+  color: green

package.json

@@ -10,6 +10,7 @@
     "clean": "shx rm -rf dist/*",
     "debug": "node --inspect-brk -r dotenv/config src/main.js",
     "lint": "eslint . --cache --fix",
+    "start": "node -r dotenv/config src/main.js",
     "test": "jest"
   },
   "dependencies": {

src/main.js

@@ -3,7 +3,8 @@ const { synchronizeBranches } = require("./synchronize");
 
 async function main() {
   try {
-    await synchronizeBranches();
+    const path = core.getInput("path", { required: true });
+    await synchronizeBranches(path);
   } catch (e) {
     core.setFailed(e.message);
   }

src/synchronize.js

@@ -27,23 +27,24 @@ async function getChildRepositories(path) {
 }
 
 /**
- * Attempt to fetch a matching branch in every git repository in the current directory.
+ * Attempt to fetch a matching branch in every git repository in a directory
+ * @param {string} path the directory containing the repositories to synchronize
  */
-async function synchronizeBranches() {
+async function synchronizeBranches(path) {
   if (context.ref === "refs/heads/master" || context.ref.startsWith("refs/tags/")) {
     core.info(`Skipping synchronize for ${context.ref}`);
     return;
   }
 
   const branch = basename(context.ref);
-  const children = (await getChildRepositories(".")).filter(
-    (path) => basename(path) !== context.repo.repo
+  const children = (await getChildRepositories(path)).filter(
+    (child) => basename(child) !== context.repo.repo
   );
 
   for (let i = 0; i < children.length; ++i) {
-    const path = children[i];
-    const name = basename(path);
-    const git = simpleGit(path);
+    const child = children[i];
+    const name = basename(child);
+    const git = simpleGit(child);
 
     // try to fetch a branch with the same name
     // eslint-disable-next-line no-await-in-loop