Gabbs

Library for building command line tools

Tutorial

Let's create a command line utility called test-gabbs. First we need to create a bootstrap file:

test-gabbs.js

const runner = require('@jobandtalent/gabbs').runner;

runner.start().then((result) => {
  console.log(result);
});

Now we'll add our first parameter. We want to call it hello-world so we'll add a file with that name in the ./command folder.

./command/hello-world.js

const BaseCommand = require('@jobandtalent/gabbs').BaseCommand;

const HelloWorld = function(args) {
  BaseCommand.call(this, args);
};

HelloWorld.prototype = new HelloWorld();

HelloWorld.prototype.run = function() {
  return new Promise((resolve) => {
    resolve('Hello world!');
  });
};

module.exports = HelloWorld;

Notice how in the method run we are returning a Promise, that's the way gabbs processes asynchronous operations.

Now we can run our first parameter:

./test-gabbs --hello-world # => Will output 'Hello world!'

Arguments

You can access to the command line arguments by using the private property _args.

Let's use that for printing a customized message:

HelloWorld.prototype.run = function() {
  const self = this;
  return new Promise((resolve) => {
    resolve(self._args[1]);
  });
};

./test-gabbs --hello-world "My custom hello world!" # => Will output 'My custom hello world!'

Logger

gabbs incorportes a logger utility in order to pretty-print output:

const logger = require('@jobandtalent/gabbs').logger;

HelloWorld.prototype.run = function() {
  return new Promise((resolve, reject) => {
    asyncTask((err, data) => {
      if (err) {
        logger.error('Something bad happened!');
        reject();
      } else {
        logger.log('Processed finished');
        resolve(data);
      }
    });
  });
};

Running processes

In order to implement more complex commands you can use the Spawn object that will let you to run external tasks.

The Spawn object provides a layer of Promises so you can return it directly in your run method.

const Spawn = require('@jobandtalent/gabbs').Spawn;

HelloWorld.prototype.run = function() {
  const process = new Spawn();
  return process.run('sh', ['./script.sh', 'first-parameter']);
};

You can chain subprocess execution by using Promise.all:

HelloWorld.prototype.run = function() {
  ...
  return Promise.all([
    process.run('sh', ['./script.sh', 'first-parameter']),
    process.run('npm', ['install', '--dev'])
  ]);
};

Accessing to the github api

Another utility is the GHApi wrapper that encapsulates the gh library in order to provide a layer of Promises for accessing to the github api.

Suppose that we want to add a new parameter to our tool that reads a file from github:

./command/github-test.js

const GHApi = require('@jobandtalent/gabbs').GHApi;

GithubTest.prototype.run = function() {
  const api = new GHApi();
  // Here you will need to create a github application token
  // @see https://help.github.com/articles/creating-an-access-token-for-command-line-use/
  api.connect('username', 'github-token');

  return new Promise((resolve, reject) => {
    api.getFileAtRevision(self._args[1], self._args[2], self._args[3])
    .then((file) => {
       resolve(file.content);
     });
  });
};

Now, with this command we have a way of reading from command line any file from github:

# Output package.json file from the jobandtalent/gabbs repository
./test-gabbs --github-test jobandtalent gabbs package.json

The GHApi object provides the following methods:

connect = function(username, token) {};
getFilesFromPullRequest = function(user, repo, id) {};
getFileAtRevision = function(user, repo, path, ref) {};
extractRepoInfoFromUrl = function(url) {};
createRelease = function(owner, repo, tag) {};

License

Apache 2

Maintainer

Jobandtalent Frontend Guild