How to access a service in Github Actions CI/CD? - github

Question

I'm trying to set up a CI/CD pipeline in GitHub Actions for my Elixir project.
I can fetch dependencies, compile them, check formatting, credo... But when the tests starts, I'm not able to reach the PostgreSQL service declared on the YAML.
How can I link both containers? (Elixir and PostgreSQL)
According to the logs shown on GitHub Actions, both containers are on the same Docker network, so they should be reachable from each other using their network aliases. However, when I try to connect to the postgres one, it says NXDOMAIN. Also the ping doesn't work, as expected.
The content of my workflow:
name: Elixir CI
on: push
jobs:
build:
runs-on: ubuntu-18.04
container:
image: elixir:1.9.1
services:
postgres:
image: postgres
ports:
- 5432:5432
env:
POSTGRES_USER: my_app
POSTGRES_PASSWORD: my_app
POSTGRES_DB: my_app_test
steps:
- uses: actions/checkout#v1
- name: Install Dependencies
env:
MIX_ENV: test
run: |
cp config/test.secret.ci.exs config/test.secret.exs
mix local.rebar --force
mix local.hex --force
apt-get update -qqq && apt-get install make gcc -y -qqq
mix deps.get
- name: Compile
env:
MIX_ENV: test
run: mix compile --warnings-as-errors
- name: Run formatter
env:
MIX_ENV: test
run: mix format --check-formatted
- name: Run Credo
env:
MIX_ENV: test
run: mix credo
- name: Run Tests
env:
MIX_ENV: test
run: mix test
Also, on Elixir I have set up the test task to connect to postgres:5432, but it says the host does not exist.
According to some tutorials and examples I found on the Internet, this configurations looks like valid, but nothing I could do made it work.

Answer 1

You need to pass the name of the service ("postgres") as POSTGRES_HOST to the application and set the port POSTGRES_PORT: ${{ job.services.postgres.ports[5432] }} (spaces matter.)
Github CI dynamically routes port and host to it.
I wrote a blog post on the subject a couple of days ago.