CircleCI 2 speeds up your CI build time drastically

CircleCI 2 has been released, which makes your CI faster and flexible.

I’ve accomplished 3 times faster CI build time on my public project.

Here is how I configured my circle.yml.

Before: Circle 1.0 configuration

Circle 1.0 configuration is very simple.

# circle.yml
machine:
  ruby:
    version: 2.4.1
general:
  artifacts:
    - coverage
    - tmp/capybara

After: Circle 2.0 configuration

Circle 2.0 configuration becomes a bit overwhelming, but I’ll explain it one by one.

# .circleci/config.yml
jobs:
  build:
    working_directory: ~/app
    docker:
      - image: circleci/ruby:2.5-node-browsers
        environment:
          RAILS_ENV: test
    steps:
      - checkout
      # Restore bundle cache
      - type: cache-restore
        key: bundle-{{ checksum "Gemfile.lock" }}
      # Bundle install dependencies
      - run: bundle install --path vendor/bundle
      # Store bundle cache
      - type: cache-save
        key: bundle-{{ checksum "Gemfile.lock" }}
        paths:
          - vendor/bundle
      # Database setup
      - run: bundle exec rails db:create db:schema:load
      # RSpec
      - run: bundle exec rspec
      - store_artifacts:
          path: coverage
      - store_artifacts:
          path: tmp/capybara

Working Directory

First of all, set your working_directory, any name is okay.

working_directory: ~/app

docker image

Then, you need to specify base docker image on CircleCI 2. In this case, I used CircleCI official docker image listed here(All available images are listed here).

docker:
  - image: circleci/ruby:2.5-node-browsers
    environment:
      RAILS_ENV: test

In environment section, I configured environment variables for the base image.

Repository checkout

This line means checkout your code base from the repository.

- checkout

Bundle cache configuration

As of CircleCI 2, you need to configured cache setting by yourself. In my Rails project, bundler is used, so I configured bundle install cache as the following.

# Restore bundle cache
- type: cache-restore
  key: bundle-{{ checksum "Gemfile.lock" }}

# Bundle install dependencies
- run: bundle install --path vendor/bundle

# Store bundle cache
- type: cache-save
  key: bundle-{{ checksum "Gemfile.lock" }}
  paths:
    - vendor/bundle

Rails testing

Rails database setup and runnning RSpec:

# Database setup
- run: bundle exec rails db:create db:schema:load
# RSpec
- run: bundle exec rspec

PhantomJS

Update: If you use circleci/ruby:2.5-node-browsers docker image, PhantomJS is bundled in the image. Therefore, you don’t have to follow the following step.

~~I used poltergeist as a Capybara javascript driver. It requires PhantomJS as a dependency but official Ruby docker image doesn’t include PhantomJS, so I needed to install PhantomJS by myself.~~

- run:
    name: Install PhantomJS
    command: |
      mkdir -p ~/.phantomjs/${PHANTOM_JS_VERSION}
      curl -L --output ~/.phantomjs/${PHANTOM_JS_VERSION}/phantomjs.tar.bz2 https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-${PHANTOM_JS_VERSION}-linux-x86_64.tar.bz2
      tar xfvj ~/.phantomjs/${PHANTOM_JS_VERSION}/phantomjs.tar.bz2 -C ~/.phantomjs/${PHANTOM_JS_VERSION}/
      chmod ugo+x ~/.phantomjs/${PHANTOM_JS_VERSION}/phantomjs-${PHANTOM_JS_VERSION}-linux-x86_64/bin/phantomjs
      sudo ln -sf ~/.phantomjs/${PHANTOM_JS_VERSION}/phantomjs-${PHANTOM_JS_VERSION}-linux-x86_64/bin/phantomjs /usr/local/bin/phantomjs

~~I created environment variable of PhantomJS version(PHANTOM_JS_VERSION) so that we can upgrade PhantomJS version easily.~~

Artifacts

You can upload artifacts by specifying store_artifacts and the path.

- store_artifacts:
    path: coverage
- store_artifacts:
    path: tmp/capybara

Comparison

CircleCI 1.0 Phase	CircleCI 1.0	CircleCI 2.0	improvement
INFRASTRUCTURE	25 sec	1 sec	25x faster
CHECKOUT	10 sec	1 sec	10x faster
MACHINE(cache restore)	15 sec	3 sec	5x faster
DEPENDENCIES(bundle install)	6 sec	1 sec	6x faster
DATABASE	11 sec	6 sec	2x faseter
TEST(RSpec)	20 sec	22 sec	-
TEARDOWN(artifacts)	26 sec	1 sec	26x fasetr
Total build time on CircleCI	02:02	00:40	3x faster

* 0 sec is rounded to 1 sec

Conclusion

CircleCI 2.0 is much faster than CircleCI 1.0. Although CircleCI 2 configuration looks complex, it gives you flexibility and better CI experience. It’ll be worth it.

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