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 available on ddev-contrib.

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 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.[servicename].yaml naming convention and include them in executing docker-compose functionality. You can optionally create a docker-compose.override.yaml to override any configurations from the main .ddev/.ddev-docker-compose-base.yaml or any additional docker-compose files added to your project.

docker-compose.*.yaml Examples¶

• Expose an additional port 9999 to host port 9999, in a file perhaps called docker-compose.ports.yaml:

services:
  someservice:
    ports:
    - "9999:9999"

That approach usually isn’t sustainable because two projects might want to use the same port, so we expose the additional port to the Docker network and then use ddev-router to bind it to the host. This works only for services with an HTTP API, but results in having both HTTP and HTTPS ports (9998 and 9999).

services:
  someservice:
    container_name: "ddev-${DDEV_SITENAME}-someservice"
    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

Confirming docker-compose Configurations¶

To better understand how DDEV parses your custom docker-compose files, run ddev debug compose-config. 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 recommended 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>.

• Provide containers with required labels:

      labels:
        com.ddev.site-name: ${DDEV_SITENAME}
        com.ddev.approot: ${DDEV_APPROOT}
  

• 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
    • 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.