Hello! Fairly new to Dagster and to Docker as well. I'm trying to use the example from here: deploy_docker, but when I make changes to repo.py file I need to rebuild the container. There's a thread mentioning "a local bind mount" and using "QueuedRunCoordinator" or some changes to the user code docker file, but it is not very specific unfortunately. 😞 Can someone please help me understand how to setup the example project so that I don't need to rebuild image with every code change?

There's been previous discussion about this here: https://dagster.slack.com/archives/C01NXMEPJ7R/p1648265274203059

Thank you for this 🤩

Hi Jimmy! Fair warning that I am also not familiar with Docker, but I was able to make some changes to the Docker Example to avoid rebuilding the image with each code change. In the

docker_example_user_code

service (code here) I added a bind mount that maps my dagster source code directory to the working directory listed in the

Dockerfile_user_code

(file here). So the service snippet now looks like:

docker_example_user_code:
    build:
      context: .
      dockerfile: ./Dockerfile_user_code
    container_name: docker_example_user_code
    image: docker_example_user_code_image
    restart: always
    environment:
      DAGSTER_POSTGRES_USER: "postgres_user"
      DAGSTER_POSTGRES_PASSWORD: "postgres_password"
      DAGSTER_POSTGRES_DB: "postgres_db"
      DAGSTER_CURRENT_IMAGE: "docker_example_user_code_image"
    volumes: # added this section here
      - type: bind
        source: /Users/claire/Desktop/deploy_docker/src
        target: /opt/dagster/app/
    networks:
      - docker_example_network

My dagster code is located in the

/Users/claire/Desktop/deploy_docker/src

directory. The Dockerfile_user_code file then has to be edited to no longer copy the code into the working directory (So commented out

COPY repo.py /opt/dagster/app

) Then, in the

dagster.yaml

file, I added an additional volume to the

run_launcher

snippet to allow the mounted code to be accessible to the run launcher:

run_launcher:
  module: dagster_docker
  class: DockerRunLauncher
  config:
    env_vars:
      - DAGSTER_POSTGRES_USER
      - DAGSTER_POSTGRES_PASSWORD
      - DAGSTER_POSTGRES_DB
    network: docker_example_network
    container_kwargs:
      volumes: # Make docker client accessible to any launched containers as well
        - /var/run/docker.sock:/var/run/docker.sock
        - /tmp/io_manager_storage:/tmp/io_manager_storage
        - /Users/claire/Desktop/deploy_docker/src:/opt/dagster/app # This line here

After that, I was able to view dagit locally by running docker-compose up. Reloading my code via the instance status page picked up on new code changes

@claire Wow, thank you so much for the detailed explaining, Claire! This was exactly the what I needed! I only had to add

/c

in front of the source path since I am on Windows. And I also removed

/src

at the end of the source path. I suppose you have moved the

repo.py

file in the

src

folder?

yep, thats right