Setting up CircleCI

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What is CircleCI?

When we send pull request with code change we want to ensure that the changed code does not break our test. So we need to run all the tests of the application every single time we send a pull request or every single time we make a commit to the pull request.

Here, CircleCI comes into the picture. CircleCI runs those tests and provides feedback in our pull request.

CircleCI is a modern continuous integration and continuous delivery (CI/CD) platform. CircleCI automates build, test, and deployment of software.

Note: Before setting up CircleCI make sure to push your code to a Github repo to see it listed in the CircleCI projects tab.

CircleCI setup

To do CircleCI setup, we need to follow below steps:

Login at CircleCI

Visit CircleCI and login using your GitHub account.

Add project

Click the projects button from the left-hand side menu. Then select the project you want Circle-CI to test for you, and click the Setup Project button.

Then we would be navigated to a new page which would display a config file.

Build project

We should see Add config button click on it. After that click a new branch would be created in your repository as circleci-project-setup .

And it would add a generic config.yml file under the .circleci directory in root folder of the application .circleci/config.yml.

Updating config.yml file

Add the following code to .circleci/config.yml:

1version: 2.1
3  build:
4    #No. of servers/machines
5    parallelism: 1
6    docker:
7      - image: circleci/ruby:3.0.2-node-browsers
8      - image: circleci/postgres:9.6
9        environment:
10          POSTGRES_HOST_AUTH_METHOD: trust
12    #application directory change it with your application directory name
13    working_directory: ~/granite
14    environment:
15      TZ: "/usr/share/zoneinfo/America/New_York"
16      RAILS_ENV: "test"
17      RACK_ENV: "test"
19    steps:
20      - checkout
21      - run: gem install bundler:2.2.20
22      #install sqlite dependency
23      - run: sudo apt update && sudo apt install zlib1g-dev libsqlite3-dev
24      # Bundle install
25      - run:
26          bundle check --path=vendor/bundle || bundle install
27          --path=vendor/bundle --jobs=4 --retry=3
28      # Yarn install
29      - run:
30          chmod a+x ./bin/yarn && ./bin/yarn install --cache-folder
31          vendor/node_modules
32      # Ensure Rubocop has linted all Ruby files
33      - run: bundle exec rubocop
34      # Ensure Prettier+ESLint has been run on all JS files
35      - run:
36          npx prettier "./app/javascript/src/**/*.{js,jsx,json}" && npx eslint
37          "./app/javascript/src/**/*.{js,jsx,json}"
38      # Setup database
39      - run: cp config/ config/database.yml
40      - run: bundle exec rails db:create db:schema:load --trace
41      # Generate assets
42      - run: chmod a+x ./bin/webpack && ./bin/webpack
43      - run: bundle exec rails webpacker:compile
44      # Unit tests
45      - run:
46          shell: /bin/bash
47          command: bundle exec rake db:test:prepare && bundle exec rails t -v
49  version: 2
50  commit:
51    jobs:
52      - build

Note that in order to ensure linting and formatting is strictly done using the configs mentioned in the linting and formatting chapter, we added relevant tasks in CircleCI too.

If the CircleCI build fails, then you will get an email for the same. Or you can check the last commit in GitHub and confirm whether there's a green tick mark or not. Green tick mark means build has passed successfully.


This config file expects a file at config/ . We don't have that file right now. Let's add that file.

Open terminal and execute following command:

1touch config/

Now open config/ and add the following code:

1default: &default
2  adapter: sqlite3
3  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
4  timeout: 5000
7  <<: *default
8  database: db/development.sqlite3
10# Warning: The database defined as "test" will be erased and
11# re-generated from your development database when you run "rake".
12# Do not set this db to the same as development or production.
14  <<: *default
15  database: granite_test<%= ENV['CIRCLE_NODE_INDEX'] %>
18  <<: *default
19  database: db/production.sqlite3

Check in all the changes and push the changed code to GitHub. Before proceeding further please ensure that these changes are pushed to GitHub and these changes are there in the master branch of the repository.

Running a build through a pull request

Create a pull request and we will see that as soon as pull request is raised the CircleCI starts running the tests.

Common CircleCI errors and their solutions

Rubocop failing in CircleCI

This is quite possible to happen in the first run with CircleCI.

The reason is that when we create a Rails application in the first place, a lot of Ruby files will be added, but no linting nor formatting is applied to it.

Thus what we can do is to run Rubocop on all relevant files, like so, from our terminal:

1bundle exec rubocop -A

Once done, verify all offenses are corrected. You check if anymore offenses are remaining by committing the already modified files using Git, since it will invoke our Git hooks.

You might've to manually correct some Rubocop offenses in the pointed out files.

Example: Rubocop uncorrectable offenses.

Once everything is done, re-push to the GitHub branch with CircleCI tracks and things should be working.

Bundle check: Could not find 'bundler' (version)

To resolve this issue, make sure that the right version of bundler is used before building. Add the following line in your .circleci/config.yml file under steps - run: gem install bundler:version . Here version is the version with which your Gemfile.lock is bundled. It is at last line of your Gemfile.lock:

2  - checkout
3  - run: gem install bundler:2.1.4

Your Ruby version is X, but your Gemfile specified Y

To fix this issue, we need to keep the Ruby version consistent everywhere. Here are some solutions:

  1. Ensure that the Ruby version mentioned in ".circleci/config.yml" under jobs -> build -> docker -> image has the right Ruby version.
  2. Ensure that the Ruby version at the top of Gemfile has the right Ruby version.
  3. Ensure that the Ruby version in .ruby-version file has the same value.
  4. Ensure that the Ruby version file .ruby-version is present in GitHub. Some folks ignore this file.

Now, let's commit the changes:

1git add -A
2git commit -m "Setup the CircleCI"