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I have a development environment I'm dockerizing and I would like the ability to livereload my changes without having to rebuild docker images. I'm using docker compose because redis is one of my app's dependencies and I like being able to link a redis container

I have two containers defined in my docker-compose.yml :

node:
  build: ./node
  links:
    - redis
  ports:
    - "8080"
  env_file:
    - node-app.env
redis:
  image: redis
  ports:
    - "6379"

I've gotten to the point in my node app's dockerfile where I add a volume, but how do I mount the the host's directory in the volume so that all my live edits to the code are reflected in the container?

Here's my current Dockerfile:

# Set the base image to Ubuntu
FROM    node:boron
# File Author / Maintainer
MAINTAINER Amin Shah Gilani <amin@gilani.me>
# Install nodemon
RUN npm install -g nodemon
# Add a /app volume
VOLUME ["/app"]
# TODO: link the current . to /app
# Define working directory
WORKDIR /app
# Run npm install
RUN npm install
# Expose port
EXPOSE  8080
# Run app using nodemon
CMD ["nodemon", "/app/app.js"]

My project looks like this:

- docker-compose.yml - node-app.env - node/ - app.js - Dockerfile.js

Checkout their documentation

From the looks of it you could do the following on your docker-compose.yml

volumes:
    - ./:/app

Where ./ is the host directory, and /app is the target directory for the containers.

EDIT:
Previous documentation source now leads to version history, you'll have to select the version of compose you're using and look for the reference.

For the lazy – v3 / v2 / v1

Side note: Syntax remains the same for all versions as of this edit

That was an error! Thank you for catching that! Fixed, and now I get Error: Cannot find module 'express' I'm gonna try a few things now. – Amin Shah Gilani Dec 1, 2016 at 8:37 For windows containers, you'll want a windows style path like - .:c:/app (this tripped me up) – JohnnyFun Feb 12, 2020 at 1:25 Side note. If you need to mount 1 dir above the host dir, just use standard .. syntax: - ../:/app works on Linux containers and - ..\:\app works on Windows containers. At least it works with Docker engine 20.10.11 for me. – jrbe228 Feb 7, 2022 at 17:10

There are a few options

Short Syntax

Using the host : guest format you can do any of the following:

volumes:
  # Just specify a path and let the Engine create a volume
  - /var/lib/mysql
  # Specify an absolute path mapping
  - /opt/data:/var/lib/mysql
  # Path on the host, relative to the Compose file
  - ./cache:/tmp/cache
  # User-relative path
  - ~/configs:/etc/configs/:ro
  # Named volume
  - datavolume:/var/lib/mysql

Long Syntax

As of docker-compose v3.2 you can use long syntax which allows the configuration of additional fields that can be expressed in the short form such as mount type (volume, bind or tmpfs) and read_only.

version: "3.2"
services:
    image: nginx:alpine
    ports:
      - "80:80"
    volumes:
      - type: volume
        source: mydata
        target: /data
        volume:
          nocopy: true
      - type: bind
        source: ./static
        target: /opt/app/static
networks:
  webnet:
volumes:
  mydata:

Check out https://docs.docker.com/compose/compose-file/#long-syntax-3 for more info.

To add to your answer, there are also :cached and :delegated annotations in the short syntax. These matter if the host is Docker Desktop for Mac. They are documented in docker-docs.netlify.app/docker-for-mac/osxfs-caching but unfortunately not in the Docker Compose docs. – akauppi Sep 13, 2021 at 14:08 Looks like it’s been relocated here: docs.docker.com.xy2401.com/docker-for-mac/osxfs-caching – RominRonin Mar 30 at 5:41

If you would like to mount a particular host directory (/disk1/prometheus-data in the following example) as a volume in the volumes section of the Docker Compose YAML file, you can do it as below, e.g.:

version: '3'
services:
  prometheus:
    image: prom/prometheus
    volumes:
      - prometheus-data:/prometheus
volumes:
  prometheus-data:
    driver: local
    driver_opts:
      o: bind
      type: none
      device: /disk1/prometheus-data

By the way, in prometheus's Dockerfile, You may find the VOLUME instruction as below, which marks it as holding externally mounted volumes from native host, etc. (Note however: this instruction is not a must though to mount a volume into a container.):

Dockerfile

VOLUME ["/prometheus"]

Refs:

  • https://docs.docker.com/compose/compose-file/compose-file-v3/#driver
  • https://docs.docker.com/compose/compose-file/compose-file-v3/#driver_opts
  • @mmell The documentation is the first Refs link (docs.docker.com/compose/compose-file/#driver) It reads: Specify which volume driver should be used for this volume. Defaults to whatever driver the Docker Engine has been configured to use, which in most cases is local – Yuci Aug 1, 2019 at 13:15 @mmell, you can find more details from this question: stackoverflow.com/questions/42195334/… – Yuci Aug 1, 2019 at 13:26 @mmell Basically, those options are driver-dependent, and the built-in local driver on Linux accepts options similar to the linux mount command: man7.org/linux/man-pages/man8/mount.8.html. You can find more discussion at github.com/moby/moby/issues/19990#issuecomment-248955005, and stackoverflow.com/questions/35841241/… – Yuci Aug 2, 2019 at 13:31 This answer should be the accepted one for a separate question about how to mount a host directory across multiple containers; twas hard to find this! – jiminikiz Nov 8, 2019 at 20:22 - ./node:/app

    I moved the npm install && nodemon app.js pieces into a CMD because RUN adds things to the Union File System, and my volume isn't part of UFS.

    # Set the base image to Ubuntu
    FROM    node:boron
    # File Author / Maintainer
    MAINTAINER Amin Shah Gilani <amin@gilani.me>
    # Install nodemon
    RUN npm install -g nodemon
    # Add a /app volume
    VOLUME ["/app"]
    # Define working directory
    WORKDIR /app
    # Expose port
    EXPOSE  8080
    # Run npm install
    CMD npm install && nodemon app.js
    

    we have to create your own docker volume mapped with the host directory before we mention in the docker-compose.yml as external

    1.Create volume named share

    docker volume create --driver local \
    --opt type=none \
    --opt device=/home/mukundhan/share \
    --opt o=bind share
    

    2.Use it in your docker-compose

    version: "3"
    volumes:
      share:
        external: true
    services:
      workstation:
        container_name: "workstation"
        image: "ubuntu"
        stdin_open: true
        tty: true
        volumes:
          - share:/share:consistent
          - ./source:/source:consistent
        working_dir: /source
        ipc: host
        privileged: true
        shm_size: '2gb'
        container_name: "db"
        image: "ubuntu"
        stdin_open: true
        tty: true
        volumes:
          - share:/share:consistent
        working_dir: /source
        ipc: host
    

    This way we can share the same directory with many services running in different containers

    In docker-compose.yml you can use this format:

    volumes:
        - host directory:container directory
    

    according to their documentation

    Here is my working example for Node.js application and MongoDB database :

    docker-compose.yml

    version: '3'
    services: 
        my-app:
            container_name: my-app-container
            restart: always
            build: .
            volumes:
                - './storage:/usr/src/app/storage'
            ports: 
                - "3000:3000"
            links:
                - my-app-db
        my-app-db:
            container_name: my-app-db-container
            image: mongo
            restart: always
            volumes:
                - './data:/data/db'          
            ports:
                - "27017:27017"
    

    Dockerfile

    FROM node:16.13.2
    RUN mkdir -p /usr/src/app
    WORKDIR /usr/src/app
    COPY package.json ./
    RUN npm install
    COPY . /usr/src/app/
    EXPOSE 3000
    CMD [ "npm", "start"]
    

    Sharing redis golang docker-compose.yaml. Using bind-mount I've achieved it.

    version: '3.0'
    services:
      redisdb:
        image: redis:6.0
        restart: always
        ports:
          - "6379:6379"
        container_name: redisdb-container
        command: ["redis-server", "--bind", "redisdb", "--port", "6379"]
      urlshortnerservice:
        depends_on:
          - redisdb
        ports:
          - "7777:7777"
        restart: always
        container_name: url-shortner-container
        image: url-shortner-service
        volumes:
          - ../pkg/repository/filestorage:/pkg/repository/filestorage #host directory:container directory
            

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