Parallelizing Builds In Travis CI

Ember JS + Python

A little background: over the last few months, I have been contributing to open source organization, FOSSASIA, where I’m working on a project called BadgeYAY. It is a badge generator with a simple web UI to add data and generate printable badges in PDF.

The BadgeYAY project is now divided into two parts, i.e front-end with Ember JS and back-end with REST-API, programmed in Python.

Now, one of the challenging job is that it should support uncoupled architecture. It should therefore run tests for the front-end and back-end, i.e, of two different languages on isolated instances, by making use of isolated parallel builds.

In this blog, I’ll be discussing how I have configured Travis CI to run the tests in parallel in isolated parallel builds in BadgeYAY in my Pull Request.

First, let’s understand what is Parallel Travis CI build and why we need it. Then we will move on to configuring the travis.yml file to run tests parallely. Let’s get started and understand it step by step.

Why Parallel Travis CI Build?

The integration test suites tend to test more complex situations through the whole stack, which incorporates front-end and back-end. They likewise have a tendency to be the slowest part, requiring various minutes to run, here and there, even up to 30 minutes.

To accelerate a test suite like that, we can split it up into a few sections, utilizing Travis build matrix feature. Travis will decide the build matrix based on environment variables and schedule two builds to run.

Now our objective is clear. We have to configure travis.yml to build in parallel. Our project requires two buildpacks, Python and node_js, running the build jobs for both them would speed up things by a considerable amount.

It seems be possible now to run several languages in one .travis.yml file using the matrix:include feature.

Below is the code snippet of the travis.yml file for the BadgeYAY project in order to run build jobs in a parallel fashion.

sudo: required
dist: trusty

# check different combinations of build flags which is able to divide builds into “jobs”.
matrix:

# Helps to run different languages in one .travis.yml file
 include:

# First Job in Python language.
 — language: python3

apt:
 packages:
 — python-dev

python:
 — 3.5
 cache:
 directories:
 — $HOME/backend/.pip-cache/
 
 before_install:
 — sudo apt-get -qq update
 — sudo apt-get -y install python3-pip
 — sudo apt-get install python-virtualenv

install:
 — virtualenv -p python3 ../flask_env
 — source ../flask_env/bin/activate
 — pip3 install -r backend/requirements/test.txt — cache-dir

before_script:
 — export DISPLAY=:99.0
 — sh -e /etc/init.d/xvfb start
 — sleep 3

script:
 — python backend/app/main.py >> log.txt 2>&1 &
 — python backend/app/main.py > /dev/null &
 — py.test — cov ../ ./backend/app/tests/test_api.py

after_success:
 — bash <(curl -s [https://codecov.io/bash)](https://codecov.io/bash%29)

# Second Job in node js language.
 — language: node_js
 node_js:
 — “6”

addons:
 chrome: stable

cache:
 directories:
 — $HOME/frontend/.npm

env:
 global:
 # See [https://git.io/vdao3](https://git.io/vdao3) for details.
 — JOBS=1

before_install:
 — cd frontend
 — npm install
 — npm install -g ember-cli
 — npm i eslint-plugin-ember@latest — save-dev
 — npm config set spin false

script:
 — npm run lint:js
 — npm test

Now we have added travis.yml and pushed it to the project repository. Here is the screenshot of passing Travis CI after parallel build jobs.

The related Pull Request of this work is https://github.com/fossasia/badgeyay/pull/512

With that, I have reached the end of our discussion on Parallelizing Builds In Travis CI. I wrote this post as a solution to this issue in BadgeYAY project. If you liked this post, consider having a look at my other work on GitHub 🙂.

Source: Travis CI documentation

PS: Constructive criticism is very much wanted. 🙂