Github Actions配置Ruby项目遇PG::ConnectionBad域名解析失败求助

问题核心 #

错误提示里的主机名是db，但你在GitHub Actions的环境变量中配置的是localhost，说明你的Rails项目config/database.yml文件的test环境配置里，数据库主机被硬编码为db，没有正确读取环境变量，导致连接失败。同时还存在环境变量密码不匹配的问题。

修复步骤 #

1. 修正config/database.yml的test环境配置

确保test环境的配置优先读取环境变量，避免硬编码主机名：

test:
  adapter: postgresql
  database: <%= ENV.fetch("PG_DATABASE") { "your_app_test" } %>
  host: <%= ENV.fetch("PG_HOST") { "localhost" } %>
  username: <%= ENV.fetch("PG_USER") { "postgres" } %>
  password: <%= ENV.fetch("PG_PASSWORD") { "postgres" } %>
  port: 5432
  encoding: unicode

替换your_app_test为你实际的测试数据库名称。

2. 统一GitHub Actions中的密码配置

你在services.postgres里设置的POSTGRES_PASSWORD是postgres，但在Setup database步骤的PG_PASSWORD写的是password，两者不匹配会导致认证失败，修正为一致的密码：

- name: Setup database
  env:
    PG_DATABASE: postgres
    PG_HOST: localhost
    PG_USER: postgres
    PG_PASSWORD: postgres # 与services中的密码保持一致
    RAILS_ENV: test
    WITH_COVERAGE: true
    DISABLE_SPRING: 1
  run: |
    bundle exec rails db:setup

3. 简化冗余的GitHub Actions步骤

ruby/setup-ruby@v1的bundler-cache: true已经会自动安装bundler和依赖包，不需要单独执行gem install bundler和bundle install，优化后的完整配置如下：

name: CI

on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]

jobs:
  test:
    runs-on: ubuntu-latest

    services: 
      postgres:
        image: postgres
        env:
          POSTGRES_PASSWORD: postgres
        ports: ['5432:5432']
        # 添加健康检查，确保PostgreSQL完全启动后再执行后续步骤
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    steps:
      - uses: actions/checkout@v2
      - name: Setup Ruby
        uses: ruby/setup-ruby@v1
        with:
          bundler-cache: true

      - name: Install System Dependencies
        run: sudo apt install -yqq libpq-dev

      - name: Setup database
        env:
          PG_DATABASE: postgres
          PG_HOST: localhost
          PG_USER: postgres
          PG_PASSWORD: postgres
          RAILS_ENV: test
          WITH_COVERAGE: true
          DISABLE_SPRING: 1
        run: |
          bundle exec rails db:setup
          
      - name: Run Tests
        env:
          PGHOST: localhost
          PGUSER: postgres
          PGPASSWORD: postgres
          RAILS_ENV: test
        run: |
          bundle exec rake test

内容的提问来源于stack exchange，提问作者Victoria