Implement sandbox execution in separated child_process to prevent shared event loop leaks

README.md

@@ -32,6 +32,7 @@ const myCode = mySandbox.compileCode('test.js', `
   }
 `);
 
+
 // express.Request compatible
 const req = {
   headers: {},
@@ -46,6 +47,50 @@ mySandbox.runScript(myCode, req).then(({status, body}) => {
 });
 ```
 
+## Example of usage (with child_process)
+
+```javascript
+const { executeFunctionInSandbox } = require('backstage-functions-sandbox/lib/ForkSandbox');
+
+const myCode = `
+  async function main(req, res) {
+    const result = req.body.x * req.body.y;
+    const name = Backstage.env.MY_VAR;
+    // you could call await here
+    return { name, result };
+  }
+`;
+
+const req = {
+  headers: {},
+  query: {},
+  body: { x: 10, y: 10}
+};
+
+const taskId = `${namespace}/${id}-${Date.now()}`; //or can be any uniq id
+
+executeFunctionInSandbox(taskId, {
+  env: {
+    MY_VAR: 'TRUE', // environment variable will be available on Backstage.env.MY_VAR
+  },
+  globalModules: [ 'path' ], // put all available modules that will allow to import
+  asyncTimeout: 10000,
+  syncTimeout: 300,
+  preCode: code, // not required to compile using sandbox.Compilecode
+  req,
+  namespace: "foo",
+  functionName: "bar",
+  options,
+})
+/* can return result using callback or using async await */
+.then(result => {
+  console.log(result)
+})
+.catch(err => {
+  console.log(err)
+})
+```
+
 ## Configuration
 
 | Name            | Description                                      | Example                               |

lib/ForkSandbox.js

@@ -0,0 +1,57 @@
+const path = require('path');
+const child_process = require('child_process');
+
+const Sandbox = require("./Sandbox");
+
+const childs = {};
+
+const codeFileName = (namespace, codeId) => {
+  return `${namespace}/${codeId}.js`;
+}
+
+const executeFunctionInSandbox = (id, data) => {
+  return new Promise((resolve, reject) => {
+    childs[id] = child_process.fork(path.resolve(__filename)); //require this file to execute process.on('message') below
+
+    childs[id].send({ id, data });
+
+    childs[id].on('message', (message) => {
+      const result = message;
+      if (result.error) {
+        reject(result.error);
+      }
+
+      resolve(result.data);
+      delete childs[id];
+
+    });
+  });
+}
+
+module.exports = {
+  executeFunctionInSandbox,
+}
+
+process.on('message', async (message) => {
+  try {
+    const { id, namespace, functionName } = message;
+    const { env, globalModules, asyncTimeout, syncTimeout, config, preCode, req, options } = message.data;
+    const sandbox = new Sandbox({ env, globalModules, asyncTimeout, syncTimeout, config });
+    const filename = codeFileName(namespace, functionName);
+
+    const _req = Object.assign({
+      method: null,
+      headers: {},
+      body: {},
+      query: {},
+    }, req);
+
+    const script = sandbox.compileCode(filename, preCode.code)
+    const result = await sandbox.runScript(script, _req, options);
+    process.send({ id, data: result });
+    process.exit(0);
+  } catch (ex) {
+    process.send({ id: message.id, data: { error: ex.message } });
+    process.exit(1);
+  }
+})