How do I declare a variable in Docker compose?

How do I declare a variable in Docker compose?

1. Substitute environment variables in Compose files. The “.env” file. Using the “–env-file” option.
2. Set environment variables in containers.
3. Pass environment variables to containers.
4. The “env_file” configuration option.
5. Set environment variables with ‘docker-compose run’
6. Configure Compose using environment variables.

Can you use variables in Docker compose file?

We can use variables in our docker-compose. yml files! The syntax is: ${SOME_VAR_NAME} . These specifically are environment variables.

How do I pass variables in Docker compose?

Pass variables into Dockerfile through Docker Compose during build. If you want to pass variables through the docker-compose process into any of the Dockerfiles present within docker-compose. yml , use the –build-arg parameter for each argument to flow into all of the Dockerfiles.

How Docker compose combines multiple compose files?

If a service is defined in both files, Compose merges the configurations using the rules described in Adding and overriding configuration. To use multiple override files, or an override file with a different name, you can use the -f option to specify the list of files.

Where is Docker compose file stored?

The Compose file is a YAML file defining services, networks and volumes. The default path for a Compose file is ./docker-compose.yml .

Can we have multiple Docker compose files?

Using Multiple Docker Compose Files Use multiple Docker Compose files when you want to change your app for different environments (e.g., dev, staging, and production) or when you want to run admin tasks against a Compose application. This gives us one way to share common configurations.

What is Docker compose file used for?

The Compose file provides a way to document and configure all of the application’s service dependencies (databases, queues, caches, web service APIs, etc). Using the Compose command line tool you can create and start one or more containers for each dependency with a single command ( docker-compose up ).

How to use environment variables in Docker shell?

It’s possible to use environment variables in your shell to populate values inside a Compose file: If you have multiple environment variables, you can substitute them by providing a path to your environment variables file. By default, the docker-compose command will look for a file named .env in the project directory

How do I import variables in Docker Compose?

First: We can export the variables so they’re available to sub-processes: Second: We can set them inline as we run the docker-compose command. We have another option too! Docker Compose will read a .env file and import variables from it!

What does Docker compose.yml file look like?

I was recently helping a friend set up Octobox and noticed they very handily provide a pre-built docker-compose.yml file for Docker Compose users! Octobox (as with many other Dockerized apps) uses environment variables for configuration, so the docker-compose command looks like this:

Which is the file path for Docker Compose?

To work around it, it is recommended to use –project-directory , which overrides the path for the .env file. This inconsistency is addressed in +v1.28 by limiting the filepath to the project directory. When you run docker-compose up, the web service defined above uses the image webapp:v1.5.