docker compose

Docker Compose

Usage

docker compose

Description

You can use the compose subcommand, docker compose [-f <arg>...] [options] [COMMAND] [ARGS...], to build and manage multiple services in Docker containers.

Use -f to specify the name and path of one or more Compose files

Use the -f flag to specify the location of a Compose configuration file.

Specifying multiple Compose files

You can supply multiple -f configuration files. When you supply multiple files, Compose combines them into a single configuration. Compose builds the configuration in the order you supply the files. Subsequent files override and add to their predecessors.

For example, consider this command line:

$ docker compose -f docker-compose.yml -f docker-compose.admin.yml run backup_db

The docker-compose.yml file might specify a webapp service.

services:
  webapp:
    image: examples/web
    ports:
      - "8000:8000"
    volumes:
      - "/data"

If the docker-compose.admin.yml also specifies this same service, any matching fields override the previous file. New values, add to the webapp service configuration.

services:
  webapp:
    build: .
    environment:
      - DEBUG=1

When you use multiple Compose files, all paths in the files are relative to the first configuration file specified with -f. You can use the --project-directory option to override this base path.

Use a -f with - (dash) as the filename to read the configuration from stdin. When stdin is used all paths in the configuration are relative to the current working directory.

The -f flag is optional. If you don’t provide this flag on the command line, Compose traverses the working directory and its parent directories looking for a compose.yaml or docker-compose.yaml file.

Specifying a path to a single Compose file

You can use the -f flag to specify a path to a Compose file that is not located in the current directory, either from the command line or by setting up a COMPOSE_FILE environment variable in your shell or in an environment file.

For an example of using the -f option at the command line, suppose you are running the Compose Rails sample, and have a compose.yaml file in a directory called sandbox/rails. You can use a command like docker compose pull to get the postgres image for the db service from anywhere by using the -f flag as follows:

$ docker compose -f ~/sandbox/rails/compose.yaml pull db

Use -p to specify a project name

Each configuration has a project name. Compose sets the project name using the following mechanisms, in order of precedence:

  • The -p command line flag
  • The COMPOSE_PROJECT_NAME environment variable
  • The top level name: variable from the config file (or the last name: from a series of config files specified using -f)
  • The basename of the project directory containing the config file (or containing the first config file specified using -f)
  • The basename of the current directory if no config file is specified Project names must contain only lowercase letters, decimal digits, dashes, and underscores, and must begin with a lowercase letter or decimal digit. If the basename of the project directory or current directory violates this constraint, you must use one of the other mechanisms.
$ docker compose -p my_project ps -a
NAME                 SERVICE    STATUS     PORTS
my_project_demo_1    demo       running

$ docker compose -p my_project logs
demo_1  | PING localhost (127.0.0.1): 56 data bytes
demo_1  | 64 bytes from 127.0.0.1: seq=0 ttl=64 time=0.095 ms

Use profiles to enable optional services

Use --profile to specify one or more active profiles Calling docker compose --profile frontend up starts the services with the profile frontend and services without any specified profiles. You can also enable multiple profiles, e.g. with docker compose --profile frontend --profile debug up the profiles frontend and debug is enabled.

Profiles can also be set by COMPOSE_PROFILES environment variable.

Configuring parallelism

Use --parallel to specify the maximum level of parallelism for concurrent engine calls. Calling docker compose --parallel 1 pull pulls the pullable images defined in the Compose file one at a time. This can also be used to control build concurrency.

Parallelism can also be set by the COMPOSE_PARALLEL_LIMIT environment variable.

Set up environment variables

You can set environment variables for various docker compose options, including the -f, -p and --profiles flags.

Setting the COMPOSE_FILE environment variable is equivalent to passing the -f flag, COMPOSE_PROJECT_NAME environment variable does the same as the -p flag, COMPOSE_PROFILES environment variable is equivalent to the --profiles flag and COMPOSE_PARALLEL_LIMIT does the same as the --parallel flag.

If flags are explicitly set on the command line, the associated environment variable is ignored.

Setting the COMPOSE_IGNORE_ORPHANS environment variable to true stops docker compose from detecting orphaned containers for the project.

Use Dry Run mode to test your command

Use --dry-run flag to test a command without changing your application stack state. Dry Run mode shows you all the steps Compose applies when executing a command, for example:

$ docker compose --dry-run up --build -d
[+] Pulling 1/1
 ✔ DRY-RUN MODE -  db Pulled                                                                                                                                                                                                               0.9s
[+] Running 10/8
 ✔ DRY-RUN MODE -    build service backend                                                                                                                                                                                                 0.0s
 ✔ DRY-RUN MODE -  ==> ==> writing image dryRun-754a08ddf8bcb1cf22f310f09206dd783d42f7dd                                                                                                                                                   0.0s
 ✔ DRY-RUN MODE -  ==> ==> naming to nginx-golang-mysql-backend                                                                                                                                                                            0.0s
 ✔ DRY-RUN MODE -  Network nginx-golang-mysql_default                                    Created                                                                                                                                           0.0s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-db-1                                     Created                                                                                                                                           0.0s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-backend-1                                Created                                                                                                                                           0.0s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-proxy-1                                  Created                                                                                                                                           0.0s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-db-1                                     Healthy                                                                                                                                           0.5s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-backend-1                                Started                                                                                                                                           0.0s
 ✔ DRY-RUN MODE -  Container nginx-golang-mysql-proxy-1                                  Started                                     Started

From the example above, you can see that the first step is to pull the image defined by db service, then build the backend service. Next, the containers are created. The db service is started, and the backend and proxy wait until the db service is healthy before starting.

Dry Run mode works with almost all commands. You cannot use Dry Run mode with a command that doesn't change the state of a Compose stack such as ps, ls, logs for example.

Options

OptionDefaultDescription
--ansiautoControl when to print ANSI control characters ("never"|"always"|"auto")
--compatibilityRun compose in backward compatibility mode
--dry-runExecute command in dry run mode
--env-fileSpecify an alternate environment file
-f, --fileCompose configuration files
--parallel-1Control max parallelism, -1 for unlimited
--profileSpecify a profile to enable
--progressautoSet type of progress output (auto, tty, plain, quiet)
--project-directorySpecify an alternate working directory
(default: the path of the, first specified, Compose file)
-p, --project-nameProject name