Create a Compose Dev Environment

Estimated reading time: 5 minutes

Use Dev Environments to collaborate on any Docker Compose-based projects.

As with a simple Dev Environment, you can create a Compose Dev Environment from a:

  • Git repository
  • Branch or tag of a Git repository
  • Subfolder of a Git repository
  • Local folder

Note

When cloning a Git repository using SSH, ensure you’ve added your SSH key to the ssh-agent. To do this, open a terminal and run ssh-add <path to your private ssh key>.

Create a Compose Dev Environment

The example below, taken from the compose-dev-env project from the Docker Samples GitHub repository, demonstrates how to create a Compose Dev Environment from a Git repository.

Note

If you want to create a Compose Dev Environment from a subdirectory of a Git repo, you need to define your own compose file in a .docker folder located in your subdirectory as currently, Dev Environments is not able to detect the main language of the subdirectory.

For more information on how to configure, see the React application with a Spring backend and a MySQL database sample or the Go server with an Nginx proxy and a Postgres database sample.

  1. From Dev Environments, select Create. The Create a Dev Environment dialog displays.
  2. Click Get Started and then copy https://github.com/dockersamples/compose-dev-env.git and add it to the Enter the Git Repository field on the Existing Git repo tab.
  3. Click Continue. This initializes the project, clones the Git code, and builds the Compose application. This:

    • Builds local images for services that are defined in the Compose file
    • Pulls images required for other services
    • Creates volumes and networks
    • Starts the Compose stack

Once your application is up and running, you can check by opening http://localhost:8080 in your browser.

The time taken to start the Compose application depends on how your application is configured, whether the images have been built, and the number of services you have defined, for example.

Note that VS Code doesn’t open directly, unlike a simple Dev Environment, as there are multiple services configured. You can hover over a service and then click on the Open in VS Code button to open a specific service in VS Code. This stops the existing container and creates a new container which allows you to develop and update your service in VS Code.

You can now update your service and test it against your Compose application.

Set up your own Compose Dev Environment

To set up a Dev Environment for your own Compose-based project, there are additional configuration steps to tell Docker Desktop how to build, start, and use the right Dev Environment image for your services.

Dev Environments use an additional docker-compose.yaml file located in the .docker directory at the root of your project. This file allows you to define the image required for a dedicated service, the ports you’d like to expose, along with additional configuration options dedicated to Dev Environments coming in the future.

Take a detailed look at the docker-compose.yaml file used in the compose-dev-env sample project.

version: "3.7"
services:
  backend:
    build:
      context: backend
      target: development
    secrets:
      - db-password
    depends_on:
      - db
  db:
    image: mariadb
    restart: always
    healthcheck:
      test: [ "CMD", "mysqladmin", "ping", "-h", "127.0.0.1", "--silent" ]
      interval: 3s
      retries: 5
      start_period: 30s
    secrets:
      - db-password
    volumes:
      - db-data:/var/lib/mysql
    environment:
      - MYSQL_DATABASE=example
      - MYSQL_ROOT_PASSWORD_FILE=/run/secrets/db-password
    expose:
      - 3306
  proxy:
    build: proxy
    ports:
      - 8080:80
    depends_on:
      - backend
volumes:
  db-data:
secrets:
  db-password:
    file: db/password.txt

In the yaml file, the build context backend specifies that that the container should be built using the development stage (target attribute) of the Dockerfile located in the backend directory (context attribute)

The development stage of the Dockerfile is defined as follows:

FROM golang:1.16-alpine AS build
WORKDIR /go/src/github.com/org/repo
COPY . .

RUN go build -o server .

FROM build AS development
RUN apk update \
    && apk add git
CMD ["go", "run", "main.go"]

FROM alpine:3.12
EXPOSE 8000
COPY --from=build /go/src/github.com/org/repo/server /server
CMD ["/server"]

The developmenttarget uses a golang:1.16-alpine image with all dependencies you need for development. You can start your project directly from VS Code and interact with the others applications or services such as the database or the frontend.

In the example, the Docker Compose files are the same. However, they could be different and the services defined in the main Compose file may use other targets to build or directly reference other images.

What’s next?

Learn how to share your Dev Environment

Dev Environments, share, collaborate, local, compose