Defining Additional Services with Docker Compose¶

Prerequisite¶

Much of DDEV’s customization ability and extensibility comes from leveraging features and functionality provided by Docker and Docker Compose. Some working knowledge of these tools is required in order to customize or extend the environment DDEV provides.

There are many examples of custom docker-compose files. The best examples are in the many available maintained DDEV add-ons.

Background¶

Under the hood, DDEV uses a private copy of docker-compose to define and run the multiple containers that make up the local environment for a project. docker-compose (also called docker compose) supports defining multiple compose files to facilitate sharing Compose configurations between files and projects, and DDEV is designed to leverage this ability.

To add custom configuration or additional services to your project, create docker-compose files in the .ddev directory. DDEV will process any files with the docker-compose.*.yaml naming convention and merge them into a full docker-compose file.

docker-compose.*.yaml Examples¶

For most HTTP-based services, use expose with HTTP_EXPOSE and HTTPS_EXPOSE environment variables. This approach allows multiple projects to run simultaneously without port conflicts:

services:
  dummy-service:
    container_name: "ddev-${DDEV_SITENAME}-dummy-service"
    labels:
      com.ddev.site-name: ${DDEV_SITENAME}
      com.ddev.approot: ${DDEV_APPROOT}
    expose:
      - "9999"
    environment:
      - VIRTUAL_HOST=$DDEV_HOSTNAME
      - HTTP_EXPOSE=9998:9999
      - HTTPS_EXPOSE=9999:9999

Only use ports for non-HTTP services that must bind directly to localhost, such as database connections or other protocols that cannot be routed through HTTP/HTTPS:

services:
  special-service:
    ports:
    - "9999:9999"  # Use only when HTTP routing is not possible

Customizing Existing Services¶

You can also modify existing DDEV services like the web container without adding new services. This is useful for adding environment variables, volumes, or build customizations:

services:
  web:
    environment:
      - CUSTOM_ENV_VAR=value
    volumes:
      - ./custom-config:/etc/custom-config:ro

For more complex customizations, you can add a custom build stage to an existing service:

services:
  web:
    build:
      context: .
      dockerfile_inline: |
        FROM ddev-webserver
        RUN apt-get update && apt-get install -y custom-package
        COPY custom-script.sh /usr/local/bin/

Confirming docker-compose Configurations¶

To better understand how DDEV parses your custom docker-compose files, run ddev debug compose-config or review the .ddev/.ddev-docker-compose-full.yaml file. This prints the final, DDEV-generated docker-compose configuration when starting your project.

Conventions for Defining Additional Services¶

When defining additional services for your project, we recommend following these conventions to ensure DDEV handles your service the same way DDEV handles default services.

• The container name should be ddev-${DDEV_SITENAME}-<servicename>. This ensures the auto-generated Traefik routing configuration matches your custom service.

• Provide containers with required labels:

  services:
    dummy-service:
      image: ${YOUR_DOCKER_IMAGE:-example/example:latest}
      labels:
        com.ddev.site-name: ${DDEV_SITENAME}
        com.ddev.approot: ${DDEV_APPROOT}
  

• When using a custom build configuration with dockerfile_inline or Dockerfile, define the image with the -${DDEV_SITENAME}-built suffix:

  services:
    dummy-service:
      image: ${YOUR_DOCKER_IMAGE:-example/example:latest}-${DDEV_SITENAME}-built
      build:
        dockerfile_inline: |
          ARG YOUR_DOCKER_IMAGE="scratch"
          FROM $${YOUR_DOCKER_IMAGE}
          # ...
        args:
          YOUR_DOCKER_IMAGE: ${YOUR_DOCKER_IMAGE:-example/example:latest}
  

  This enables DDEV to operate in offline mode once the base image has been pulled.

• Exposing ports for service: you can expose the port for a service to be accessible as projectname.ddev.site:portNum while your project is running. This is achieved by the following configurations for the container(s) being added:

  • Define only the internal port in the expose section for docker-compose; use ports: only if the port will be bound directly to localhost, as may be required for non-HTTP services.

  • To expose a web interface to be accessible over HTTP, define the following environment variables in the environment section for docker-compose:

    • VIRTUAL_HOST=$DDEV_HOSTNAME You can set a subdomain with VIRTUAL_HOST=mysubdomain.$DDEV_HOSTNAME. You can also specify an arbitrary hostname like VIRTUAL_HOST=extra.ddev.site.
    • HTTP_EXPOSE=portNum The hostPort:containerPort convention may be used here to expose a container’s port to a different external port. To expose multiple ports for a single container, define the ports as comma-separated values.
    • HTTPS_EXPOSE=<exposedPortNumber>:portNum This will expose an HTTPS interface on <exposedPortNumber> to the host (and to the web container) as https://<project>.ddev.site:exposedPortNumber. To expose multiple ports for a single container, use comma-separated definitions, as in HTTPS_EXPOSE=9998:80,9999:81, which would expose HTTP port 80 from the container as https://<project>.ddev.site:9998 and HTTP port 81 from the container as https://<project>.ddev.site:9999.

Interacting with Additional Services¶

ddev exec, ddev ssh, and ddev logs interact with containers on an individual basis.

By default, these commands interact with the web container for a project. All of these commands, however, provide a --service or -s flag allowing you to specify the service name of the container to interact with. For example, if you added a service to provide Apache Solr, and the service was named solr, you would be able to run ddev logs --service solr to retrieve the Solr container’s logs.

Third Party Services May Need To Trust ddev-webserver¶

Sometimes a third-party service (docker-compose.*.yaml) may need to consume content from the ddev-webserver container. A PDF generator like Gotenberg, for example, might need to read in-container images or text in order to create a PDF. Or a testing service may need to read data in order to support tests.

A third-party service is not configured to trust DDEV’s mkcert certificate authority by default, so in cases like this you have to either use HTTP between the two containers, or make the third-party service ignore or trust the certificate authority.

Using plain HTTP between the containers is the simplest technique. For example, the ddev-selenium-standalone-chrome service must consume content, so it conducts interactions with the ddev-webserver by accessing http://web. In this case, the selenium-chrome container accesses the web container via HTTP instead of HTTPS.

A second technique is to tell the third-party service to ignore HTTPS/TLS errors. For example, if the third-party service uses cURL, it could use curl --insecure https://web or curl --insecure https://<project>.ddev.site.

A third and more complex approach is to make the third-party container actually trust the self-signed certificate that the ddev-webserver container is using. This can be done in many cases using a custom .ddev/example/Dockerfile and some extra configuration in the .ddev/docker-compose.example.yaml. An example would be:

services:
  example:
    container_name: ddev-${DDEV_SITENAME}-example
    command: "bash -c 'mkcert -install && original-start-command-from-image'"
    # Add an image and a build stage so we can add `mkcert`, etc.
    # The Dockerfile for the build stage goes in the `.ddev/example directory` here
    image: ${YOUR_DOCKER_IMAGE:-example/example:latest}-${DDEV_SITENAME}-built
    build:
      context: example
      args:
        YOUR_DOCKER_IMAGE: ${YOUR_DOCKER_IMAGE:-example/example:latest}
    environment:
      - HTTP_EXPOSE=3001:3000
      - HTTPS_EXPOSE=3000:3000
      - VIRTUAL_HOST=$DDEV_HOSTNAME
    # Adding external_links allows connections to `https://example.ddev.site`,
    # which then can go through `ddev-router`
    # Tip: external_links are not needed anymore in DDEV v1.24.9+
    external_links:
      - ddev-router:${DDEV_SITENAME}.${DDEV_TLD}
    labels:
      com.ddev.approot: ${DDEV_APPROOT}
      com.ddev.site-name: ${DDEV_SITENAME}
    restart: 'no'
    volumes:
      - .:/mnt/ddev_config
      # `ddev-global-cache` gets mounted so we have the CAROOT
      # This is required so that the CA is available for `mkcert` to install
      # and for custom commands to work
      - ddev-global-cache:/mnt/ddev-global-cache

ARG YOUR_DOCKER_IMAGE="scratch"
FROM $YOUR_DOCKER_IMAGE

# CAROOT for `mkcert` to use, has the CA config
ENV CAROOT=/mnt/ddev-global-cache/mkcert

# If the image build does not run as the default `root` user,
# temporarily change to root. If the image already has the default setup
# where it builds as `root`, then
# there is no need to change user here.
USER root
# Give the `example` user full `sudo` privileges
RUN echo "example ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers.d/example && chmod 0440 /etc/sudoers.d/example
# Install the correct architecture binary of `mkcert`
RUN export TARGETPLATFORM=linux/$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && mkdir -p /usr/local/bin && curl --fail -JL -s -o /usr/local/bin/mkcert "https://dl.filippo.io/mkcert/latest?for=${TARGETPLATFORM}"
RUN chmod +x /usr/local/bin/mkcert
USER original_user

Optional Services¶

Services in named Docker Compose profiles will not automatically be started on ddev start. This is useful when you want to define a service that is not always needed, but can be started by an additional command when it is time to use it. In this way, it doesn’t use system resources unless needed. In this example, the busybox container will only be started if the busybox profile is requested, for example with ddev start --profiles=busybox. More than one service can be labeled for a single Docker Compose profile.

services:
  busybox:
    image: busybox:stable
    command: tail -f /dev/null
    profiles:
      - busybox
    container_name: ddev-${DDEV_SITENAME}-busybox
    labels:
      com.ddev.site-name: ${DDEV_SITENAME}
      com.ddev.approot: ${DDEV_APPROOT}