Docker Compose for Rails Developer

Transcript

1. Docker Compose for Rails developer

2. docker-compose.yml version: '2' services: web: build: . depends_on: - db

   volumes: - .:/usr/local/src ports: - 3000:3000 environment: - AWS_S3_KEY=6t87yagsdifhj db: image: postgres volumes: - ./data:/var/lib/postgresql/data ports: - 5432:5432

3. docker-compose.yml version: '2' services: <SERVICE_1_NAME>: build: <DOCKERFILE_PATH> depends_on: - <SERVICE_X_NAME>

   volumes: - <HOST_PATH>:<CONTAINER_PAHT> ports: - <HOST_PORT>:<CONTAINER_PORT> environment: - <ENV_VAR_NAME>=<ENV_VAR_VALUE> <SERVICE_X_NAME>: image: <IMAGE_NAME> volumes: - <HOST_PATH>:<CONTAINER_PAHT> ports: - <HOST_PORT>:<CONTAINER_PORT>

4. Commands • build • depends_on • volumes • ports •

   environment • image

5. build • create new image • use cached image when

   possible • relative path from the docker-compose.yml • require Dockerfile at the path

6. depends_on • all services in depends_on will be starting before

   the particular service • auto create dns record for the dependent service (http://db:5432)

7. volumes • link host folder into container • any file

   change on host will effect file inside the container • any file change inside the container will change the file on the host • files will be persisted even the container is stopped

8. ports • allow the container’s port being access via host

   port • could be different port number • could not be the port being used on host • could be range of port

9. ports vs. expose • expose allows the container communicate between

   containers • port mapping allows outside traffic to communicate with the container

10. environment • environment variables for the service • can use

    .env files with env_file keyword

11. image • pull image from docker hub • use cached

    image when possible • auto start the container with CMD or ENTRYPOINT specified in that image • use all configurations from that image • configurations will be overwritten by commands specified in docker-compose.yml

12. Services

13. Services • db • web • worker (optional) • es

    (optional) • redis (optional)

14. db • image name = postgres • database default username

    = postgres • data directory = /var/lib/postgresql/data • there is no default password • port 5432 is exposed automatically

15. web • built locally • base on some version of

    ruby image • depends on db, so we have db started before the Rails app • map host port 3000 into container port 3000, so we can access the web app from browser

16. worker • use the same image as web • depends

    on web, so we let the web image builds first, then also start the worker container from it

17. es • image name = elasticsearch • ports 9200 and

    9300 are exposed automatically • no need to mount volume, we can reindex the data easily

18. redis • image name = redis • ports 6379 is

    exposed automatically • no need to mount volume, everything is in the RAM anyway

19. Command Line

20. CLI • run <SERVICE> <COMAND> • logs (-f) • up

    • start • down • stop

21. run • start a new container with the command •

    using the service’s configurations • attach the terminal to that container • the container will be stopped on exit (not destroy)

22. logs • show logs from all services • supply -f

    option to show logs live streaming • supply the service name to show logs from that service only

23. up • pull/build images and start all services in docker-compose.yml

    • use cached images when possible • supply -d option to make it run in background

24. start • start the stopped containers • does not load

    images • does not create the containers from images • container state will be the same

25. down • stop and remove all running containers • also

    remove containers started from run command • does not remove cached images

26. stop • stop all running containers • does not remove

    containers • container state will stay untouched • does not effect images

27. Misc.

28. Workflow • docker-compose up / start • dev • docker-compose

    stop • (optional) docker-compose down

29. ZSH Plugin • plugin name: docker-compose • use dco instead

    of docker-compose • add autocomplete for the command