Deploy Concourse CI using Docker

Concourse CI is an awesome open source continuous integration tool. If you are not using Gitlab, and want to setup a CI server, it is a good choice.

Concourse CI provides Docker image and docker compose sample config. But when I run the hello world example, I have met several problems.

First, my Docker host kernel version is too low, which caused the error:

unknown capability "CAP_AUDIT_READ"

The solution is upgrading kernel. Concourse requires version 3.19+¹. Ubuntu 14.04 can use following command:

sudo apt-get install --install-recommends linux-generic-lts-wily

Second, if Concourse is deployed via docker compose, DNS is changed to loopback address. The job will fail because of DNS lookup error:

lookup registry-1.docker.io on 127.0.0.11:53: read udp 127.0.0.1:54286->127.0.0.11:53: read: connection refused

Just add DNS config based on official compose sample to solve this error. I have configured custom DNS for concourse-web and concourse-worker. It is also required to setup a DNS for concourse-worker using environment variable CONCOURSE_GARDEN_DNS_SERVER²。

If your cloud server provider has its own DNS servers, log into any host and check /etc/resolv.conf. Use the DNS servers to replace 8.8.8.8 和 8.8.4.4 in the example below.

concourse-db:
  image: postgres:9.5
  environment:
    POSTGRES_DB: concourse
    POSTGRES_USER: concourse
    POSTGRES_PASSWORD: "${POSTGRES_PASSWORD}"

concourse-web:
  image: concourse/concourse
  links: [concourse-db]
  command: web
  ports: ["8080:8080"]
  volumes: ["keys:/concourse-keys"]
  environment:
    CONCOURSE_BASIC_AUTH_USERNAME: admin
    CONCOURSE_BASIC_AUTH_PASSWORD: "${CONCOURSE_BASIC_AUTH_PASSWORD}"
    CONCOURSE_EXTERNAL_URL: "${CONCOURSE_EXTERNAL_URL}"
    CONCOURSE_POSTGRES_DATA_SOURCE: "postgres://concourse:${POSTGRES_PASSWORD}@concourse-db:5432/concourse?sslmode=disable"
  dns:
    - 8.8.8.8
    - 8.8.4.4

concourse-worker:
  image: concourse/concourse
  privileged: true
  links: [concourse-web]
  command: worker
  volumes: ["keys:/concourse-keys"]
  environment:
    CONCOURSE_TSA_HOST: concourse-web
    CONCOURSE_GARDEN_DNS_SERVER: 8.8.8.8
  dns:
    - 8.8.8.8
    - 8.8.4.4

The last, Concourse does not pull docker images via the docker daemon in docker host machine. So the config registry-mirror is ignored. The config must be added in the resource source config³. It is tedius that cannot be set as a global config.

jobs:
- name: hello-world
  plan:
  - task: say-hello
    config:
      platform: linux
      image_resource:
        type: docker-image
        source:
          registry_mirror: https://changeme.mirror.aliyuncs.com
          repository: alpine
      run:
        path: echo
        args: ["Hello, world!"]