kendralabs/code-component repository overview

⁠code-component

⁠Available Variables and Libraries

Here are the available variables and libraries that can be used within the context of execution. The most up-to-date list can always be found in be used within the context of execution or in code.js of the component. Below is a sample for the reference. Built-in Node.js global objects are also supported.

⁠Elastic.io Specific Functionality

• msg - incoming message containing the payload from the previous step
• cfg - step's configuration. At the moment contains only one property: code (the code, being executed). May contain further attributes passed through the fields propery in the flow definition
• snapshot - step's snapshot
• messages - utility for convenient message creation
• emitter user to emit messages and errors

⁠Other Libraries/functions

• wait(numberOfMilliscondsToSleep) - Utility function for sleeping
• request⁠ - Http Client (wrapped in co - this library⁠ so that it is pre-promisified)
• _ - Lodash⁠

⁠Code component usage Examples

Use code is very simple, just do following:

async function run(msg, cfg, snapshot) {
  console.log('Incoming message is %s', JSON.stringify(msg));
  const body = { result : 'Hello world!' };
  // You can emit as many data messages as required
  await this.emit('data', { body });
  console.log('Execution finished');
}

Please note if you have a simple one-in-one-out function you can simply return a JSON object as a result of your function, it will be automatically emitted as data.

⁠Common usage scenarios

⁠Doing complex data transformation

JSONata⁠ is great however sometimes it's easier to do things in JavaScript, if you want to transorm an incoming message with code, just use following sample:

async function run(msg, cfg, snapshot) {
  return {
      addition: 'You can use code',
      keys: Object.keys(msg)    
  };
}

⁠Calling an external REST API

It's very simple to code a small REST API call out of the Code component, see following example:

async function run(msg, cfg, snapshot) {
  const res = await request.get({
    uri: 'https://postman-echo.com/get?foo1=bar1&foo2=bar2',
    json: true  
  });
  return {
    arguments: response.body.args
  }
}