Travis CI¶

In this section we are going to use Travis CI as our continuous-integration service. Travis CI is mostly used for building and running tests for projects hosted at GitHub. It supports different programming languages and for our particular case, it supports the Crystal language.

Note

If you are new to continuous integration (or you want to refresh the basic concepts) we may start reading the core concepts guide.

Now let's see some examples!

Build and run specs¶

Using `latest` and `nightly`¶

A first (and very basic) Travis CI config file could be:

.travis.yml

language: crystal

That's it! With this config file, Travis CI by default will run crystal spec. Now, we just need to go to Travis CI dashboard to add the GitHub repository.

Let's see another example:

.travis.yml

language: crystal

crystal:
  - latest
  - nightly

script:
  - crystal spec
  - crystal tool format --check

With this configuration, Travis CI will run the tests using both Crystal latest and nightly releases on every push to a branch on your Github repository.

Note

When creating a Crystal project using crystal init, Crystal creates a .travis.yml file for us.

Using a specific Crystal release¶

Let's suppose we want to pin a specific Crystal release (maybe we want to make sure the shard compiles and works with that version) for example Crystal 0.31.1.

Travis CI only provides runners to latest and nightly releases directly and so, we need to install the requested Crystal release manually. For this we are going to use Docker.

First we need to add Docker as a service in .travis.yml, and then we can use docker commands in our build steps, like this:

.travis.yml

language: minimal

services:
  - docker

script:
  - docker run -v $PWD:/src -w /src crystallang/crystal:0.31.1 crystal spec

Note

We may read about different (languages)[https://docs.travis-ci.com/user/languages/] supported by Travis CI, included minimal.

Note

A list with the different official Crystal docker images is available at DockerHub.

Using `latest`, `nightly` and a specific Crystal release all together!¶

Supported runners can be combined with Docker-based runners using a Build Matrix. This will allow us to run tests against latest and nightly and pinned releases.

Here is the example:

.travis.yml

matrix:
include:
  - language: crystal
    crystal:
      - latest
    script:
      - crystal spec

  - language: crystal
    crystal:
      - nightly
    script:
      - crystal spec

  - language: bash
    services:
      - docker
    script:
      - docker run -v $PWD:/src -w /src crystallang/crystal:0.31.1 crystal spec

Installing shards packages¶

In native runners (language: crystal), Travis CI already automatically installs shards dependencies using shards install. To improve build performance we may add caching on top of that.

Using Docker¶

In a Docker-based runner we need to run shards install explicitly, like this:

.travis.yml

language: bash

services:
  - docker

script:
  - docker run -v $PWD:/src -w /src crystallang/crystal:0.31.1 shards install
  - docker run -v $PWD:/src -w /src crystallang/crystal:0.31.1 crystal spec

Note

Since the shards will be installed in ./lib/ folder, it will be preserved for the second docker run command.

Installing binary dependencies¶

Our application or maybe some shards may required libraries and packages. This binary dependencies may be installed using different methods. Here we are going to show an example using the Apt command (since the Docker image we are using is based on Ubuntu)

Here is a first example installing the libsqlite3 development package using the APT addon:

.travis.yml

language: crystal
crystal:
  - latest

before_install:
  - sudo apt-get -y install libsqlite3-dev

addons:
  apt:
    update: true

script:
  - crystal spec

Using Docker¶

We are going to build a new docker image based on crystallang/crystal, and in this new image we will be installing the binary dependencies.

To accomplish this we are going to use a Dockerfile:

Dockerfile

FROM crystallang/crystal:latest

# install binary dependencies:
RUN apt-get update && apt-get install -y libsqlite3-dev

And here is the Travis CI configuration file:

.travis.yml

language: bash

services:
  - docker

before_install:
  # build image using Dockerfile:
  - docker build -t testing .

script:
  # run specs in the container
  - docker run -v $PWD:/src -w /src testing crystal spec

Note

Dockerfile arguments can be used to use the same Dockerfile for latest, nightly or a specific version.

Using services¶

Travis CI may start services as requested.

For example, we can start a MySQL database service by adding a services: section to our .travis.yml:

.travis.yml

language: crystal
crystal:
  - latest

services:
  - mysql

script:
  - crystal spec

Here is the new test file for testing against the database:

spec/simple_db_spec.cr

require "./spec_helper"
require "mysql"

it "connects to the database" do
  DB.connect ENV["DATABASE_URL"] do |cnn|
    cnn.query_one("SELECT 'foo'", as: String).should eq "foo"
  end
end

When pushing this changes Travis CI will report the following error: Unknown database 'test' (Exception), showing that we need to configure the MySQL service and also setup the database:

.travis.yml

language: crystal
crystal:
  - latest

env:
  global:
    - DATABASE_NAME=test
    - DATABASE_URL=mysql://root@localhost/$DATABASE_NAME

services:
  - mysql

before_install:
  - mysql -e "CREATE DATABASE IF NOT EXISTS $DATABASE_NAME;"
  - mysql -u root --password="" $DATABASE_NAME < db/schema.sql

script:
  - crystal spec

We are using a schema.sql script to create a more readable .travis.yml. The file ./db/schema.sql looks like this:

schema.sql

CREATE TABLE ... etc ...

Pushing these changes will trigger Travis CI and the build should be successful!

Caching¶

If we read Travis CI job log, we will find that every time the job runs, Travis CI needs to fetch the libraries needed to run the application:

Fetching https://github.com/crystal-lang/crystal-mysql.git
Fetching https://github.com/crystal-lang/crystal-db.git

This takes time and, on the other hand, these libraries might not change as often as our application, so it looks like we may cache them and save time.

Travis CI uses caching to improve some parts of the building path. Here is the new configuration file with cache enabled:

.travis.yml

language: crystal
crystal:
  - latest

cache: shards

script:
  - crystal spec

Let's push these changes. Travis CI will run, and it will install dependencies, but then it will cache the shards cache folder which, usually, is ~/.cache/shards. The following runs will use the cached dependencies.

Travis CI¶

Build and run specs¶

Using latest and nightly¶

Using a specific Crystal release¶

Using latest, nightly and a specific Crystal release all together!¶

Installing shards packages¶

Using Docker¶

Installing binary dependencies¶

Using Docker¶

Using services¶

Caching¶

Using `latest` and `nightly`¶

Using `latest`, `nightly` and a specific Crystal release all together!¶