Continuous Integration/Deployment for Rails on Gitlab
In this blog post, we will through the necessary steps to setup Gitlab in order
to run Rails build, tests & deployment if everything will be okay.
I will put a particular attention on rails system test
and how to make them works.
We will use Heroku to deploy our staging App.
What will we achieve ?
The build Stage
The build will contain:
- Installation of dependencies
- Database setup
- Precompile of assets (assets & webpacker)
The Test Stage
The Integration tests
In this stage, we will run all our integration tests, which basically turn to
run:
bundle exec rails test
The system tests
This is the most exciting and important part to have in our CI.
The system tests are very useful in term of testing complex UI requiring a massive use
of Javascript (React of Vue app) and interacting with external services like Google
.
Map Places
The system test will mimic a regular user by clicking and filling inputs like a regular user on our App.
The main command executed in this stage is bundle exec rails test:system
.
The interacting fact in this case is the use of container to embed the Selenium
to run real browser to fetch and tests our frontend.
Chrome browser
The deploy Stage
This is an easy step, we will deploy our application to the staging environment.
The GITLAB-CI
Gitlab offer to everyone ( and we should be grateful to them for all the work
that have be done) a recipe that define how the code will be tested / deployed
and all the services needed for these tasks.
All the instructions are stored in .gitlab-ci
present in the root of our repo.
This offer us a centralized and an easy way to manage our source code and
our continues integration for FREE
.
How does it works
The CI follow these simple steps:
- Booting one or several containers aka
services
that you have specified in the.gitlab-ci
- Copy your repo in the main container.
- Run all scripts wanted in it
Use the cache to speedup the CI
Gitlab allows us to cache folders and files and use them for the next jobs.
No need to recompile all dependencies or even download them.
In our case, caching all the gems
and node_modules
will save us several minutes.
Use artifacts to debug our tests
When the system tests fails, the test will save the screenshots
in a temp
folder.
The artifacts
make possible for us to save those files and tie them to the job.
This will help us a lot when we want to debug a failing system tests.
Let's do it
1. The build
Prepare the build container
The build will be executed in a container, so we should have a container with
all the dependencies needed bundled inside.
For the modern rails app we should include:
- Ruby
- Node + Yarn
- Some system libraries
Here is the dockerfile
FROM ruby:2.4.3
RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN curl -sL https://deb.nodesource.com/setup_8.x | bash -
RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
RUN apt-get update -qqy && apt-get install -qqyy yarn nodejs postgresql postgresql-contrib libpq-dev cmake
RUN rm -rf /var/lib/apt/lists/*
Easy yay !
Build the container
docker build .
Sending build context to Docker daemon 2.048kB
Step 1/6 : FROM ruby:2.6.5
2.6.5: Pulling from library/ruby
16ea0e8c8879: Pull complete
50024b0106d5: Pull complete
ff95660c6937: Pull complete
9c7d0e5c0bc2: Pull complete
29c4fb388fdf: Pull complete
069ad1aadbe0: Pull complete
e7188792d9dd: Pull complete
bae7e74440d1: Pull complete
Digest: sha256:2285f291f222e1b53d22449cc52bad2112f519bcce60248ea1c4d5e8f14c7c04
Status: Downloaded newer image for ruby:2.6.5
---> 2ff4e698f315
Step 2/6 : RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
---> Running in abb67e50af3e
Warning: apt-key output should not be parsed (stdout is not a terminal)
OK
Removing intermediate container abb67e50af3e
---> 461e2dd2134d
Step 3/6 : RUN curl -sL https://deb.nodesource.com/setup_8.x | bash -
---> Running in 414f508a391c
## Installing the NodeSource Node.js 8.x LTS Carbon repo...
.....
Processing triggers for libc-bin (2.28-10) ...
Removing intermediate container af1183021a8d
---> 603cab5f6952
Step 6/6 : RUN rm -rf /var/lib/apt/lists/*
---> Running in 53c5950a25c1
Removing intermediate container 53c5950a25c1
---> 42b50699301e
Successfully built 42b50699301e
Tag it
docker tag 42b50699301e registry.gitlab.com/[ORG]/[REPO]/[CONTAINER]:v1
Now, we should publish this container to enable GitlabCI to use it.
Gitlab
provide for us a container registry ! for free again !
So we just need to push this container in the project registry.
First, you should login to gitlab registry
docker login registry.gitlab.com
# use your gitlab credential
and PUSH
docker push registry.gitlab.com/[ORG]/[REPO]/[CONTAINER]:v1 # v1 is my version tag
If you have ADSL
internet connection with a poor uploading speed, you can go
take a nap ;)
Once the push finishes, we are good to go to the next step.
The build script
This is the main build part in the gitlab-ci file
image: "registry.gitlab.com/[ORG]/[REPO]/[CONTAINER]:v1"
variables:
LC_ALL: C.UTF-8
LANG: en_US.UTF-8
LANGUAGE: en_US.UTF-8
RAILS_ENV: "test"
POSTGRES_DB: test_db
POSTGRES_USER: runner
POSTGRES_PASSWORD: ""
# cache gems and node_modules for next usage
.default-cache: &default-cache
cache:
untracked: true
key: my-project-key-5.2
paths:
- node_modules/
- vendor/
- public/
build:
<<: *default-cache
services:
- postgres:latest
stage: build
script:
- ruby -v
- node -v
- yarn --version
- which ruby
- gem install bundler --no-ri --no-rdoc
- bundle install --jobs $(nproc) "${FLAGS[@]}" --path=vendor
- yarn install
- cp config/database.gitlab config/database.yml
- RAILS_ENV=test bundle exec rake db:create db:schema:load
- RAILS_ENV=test bundle exec rails assets:precompile
So we are using the previously created image to host the build.
We should add to the project a config/database.gitlab
to replace the original
database config and use custom host and credential to connect to postgres
container booted by the GitlabCI.
services:
- postgres:latest
Gitlab when reading this line will bootup a database container (postgress) and
will use the variables defined before to setup the database
POSTGRES_DB: test_db
POSTGRES_USER: runner
POSTGRES_PASSWORD: ""
The config/database.gitlab
will tell our rails app how to connect to the
database, so before the app boots, the database.yml
will be replaced by the
custom one.
test:
adapter: postgresql
encoding: unicode
pool: 5
timeout: 5000
host: postgres
username: runner
password: ""
database: test_db
2. The Integration Tests script
No need more explanation for this
integration_test:
<<: *default-cache
stage: test
services:
- postgres:latest
- redis:alpine
script:
- gem install bundler --no-ri --no-rdoc
- bundle install --jobs $(nproc) "${FLAGS[@]}" --path=vendor
- cp config/database.gitlab config/database.yml
- bundle install --jobs $(nproc) "${FLAGS[@]}" --path=vendor
- RAILS_ENV=test bundle exec rake db:create db:schema:load
- RAILS_ENV=test bundle exec rails assets:precompile
- bundle exec rake test
3. The System Tests script
The infrastructure to make possible the system test is quite interesting.
To run the test we should start a browser (in a container) and fetch the page
from the rails server (from an other container).
system_test:
<<: *default-cache
stage: test
services:
- postgres:latest
- redis:alpine
- selenium/standalone-chrome:latest
script:
- gem install bundler --no-ri --no-rdoc
- bundle install --jobs $(nproc) "${FLAGS[@]}" --path=vendor
- cp config/database.gitlab config/database.yml
- export selenium_remote_url="http://selenium__standalone-chrome:4444/wd/hub/"
- bundle install --jobs $(nproc) "${FLAGS[@]}" --path=vendor
- RAILS_ENV=test bundle exec rake db:create db:schema:load
- RAILS_ENV=test bundle exec rails assets:precompile
- bundle exec rake test:system
artifacts:
when: on_failure
paths:
- tmp/screenshots/
We should tell to capybara to use the right IP
instead of localhost
, because here we have the browser
and the server in two different containers.
In the environment/test.rb
, add these lines
net = Socket.ip_address_list.detect{|addr| addr.ipv4_private? }
ip = net.nil? ? 'localhost' : net.ip_address
config.domain = ip
config.action_mailer.default_url_options = { :host => config.domain }
Capybara.server_port = 8200
Capybara.server_host = ip
and we should tell the system test where to find the chrome driver
to control the browser, update application_system_test_case.rb
require "test_helper"
require "socket"
def prepare_options
driver_options = {
desired_capabilities: {
chromeOptions: {
args: %w[headless disable-gpu disable-dev-shm-usage] # preserve memory & cpu consumption
}
}
}
driver_options[:url] = ENV['selenium_remote_url'] if ENV['selenium_remote_url']
driver_options
end
class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
driven_by :selenium, using: :chrome, screen_size: [1400, 1400],
options: prepare_options
end
The rails system test
will take screenshots and save them to tmp/screenshots
As you can see, the screenshots are stored and attached to job, Neat!
4. The Staging deployment
This will deploy our code if build
and tests
stages succeed.
deploy_staging:
stage: deploy
variables:
HEROKU_APP_NAME: YOUR_HEROKU_APP_NAME
dependencies:
- integration_test
- system_test
only:
- master
script:
- gem install dpl
- dpl --provider=heroku --app=$HEROKU_APP_NAME --api-key=$HEROKU_API_KEY
The HEROKU_API_KEY
is stored in a safe place in the settings of the project
For more information about this, go to Gitlab variables documentation
Conclusion
Gitlab
is an amazing project and provide a very nice spot where everything is
well integrated, the coding experience is enhanced.
Finally, let's hope that the migration to Google compute engine
will provide a
better robustness to the project and less issues.
Longue vie à Gitlab !!
Cheers!
Here is the complete Gitlab CI
file
Top comments (12)
Since my Gemfile already had
gem "webdrivers"
for local running ofrails test:system
, I needed to change this to disable webdrivers so as to stop the "Failed to find Chrome binary" error:Hi Patrik,
When I print
/etc/hosts
inside a service and the main container, I get:So definitely, the
ip
of the main container is172.17.0.6
and it's referenced inside the service but with an other namecc27ba611b73
and it's the container ID. so I cannot find an easy way to fix your issue.May be you can create a issue in the repo,
gitlab
is opensource ;)The chrome is CPU intensive, using it side by side with rails server can make your system test flaky.
Have a good day
Hi, I followed this guide, but I am having problems with Chrome. When CI runs my tests, I get the following error:
Webdrivers::BrowserNotFound: Failed to find Chrome binary.
Any ideas why Chrome can't be found?
Hey,
I know that I have an issue with the latest selenium containers
Can you try with this one:
Hi,
I tried with that container version, but I'm still getting the same problem.
Are you sure that your system test is trying to connect with the remote chrome hosted inside the selenium container.
I think your issue is that the tests is trying to run in the local container and gets this error because there is no chrome installed in the build container.
Make sure that is used
My
application_system_test_case.rb
looks like this:And within the configure block of
config/environments/test.rb
I have:Hello Patrik, thankyou for your comment.
To solve your issue, I will proceed like this:
Find the hostname of the main container that run your rails app in gitlab CI, in the rest of this comment, I will refer to it as
[HOSTNAME]
setup a test domain with sub-domains using CNAME ( you can use route53 from aws for this) :
The result will be:
[HOSTNAME]
as the first result it will try to resolve[HOSTNAME]
a second time and will find theIP
because all services and the main container are linked together gitlab service aliasHope this help you
Merry Christmas
Hi, thanks for your post! It was very useful. However I'm struggling a bit to get the system tests running.
I don't know if I'm missing something, but I'm getting a lot of errors when initializing Chromedriver.
Did you include it in your docker image? Is there any script you're executing on the build phase to install chromedriver and it's dependencies?
Thanks again for a great post
Felipe
Hey Felipe,
I think the error that you are getting is when the system test is trying to connect to the chrome driver in the separated container and failed.
I think this can help you by updating this file
application_system_test_case.rb
Take attention to the code that fetch the
selenium_remote_url
from the env variableThanks! That did the trick.
Thank you for your comment, I updated the blog post.