Can you use environment variables in docker-compose?

Can you use environment variables in docker-compose?

You can set default values for environment variables using a .env file, which Compose automatically looks for in project directory (parent folder of your Compose file). The .env file feature only works when you use the docker-compose up command and does not work with docker stack deploy .

Does docker-compose inherit environment variables?

If you define an environment variable in the shell or via the command line when running docker-compose , those variables will take precedence over the . env file.

How do I pass environment variables to docker containers?

You can pass the values of environment variables from the host to your containers without much effort. Simply don’t specify a value in the command line, and make sure that the environment variable is named the same as the variable the containerized app expects: $ docker run -e var_name (…)

What does docker-compose up — build do?

Builds, (re)creates, starts, and attaches to containers for a service. Unless they are already running, this command also starts any linked services. The docker-compose up command aggregates the output of each container (essentially running docker-compose logs –follow ).

How to set default environment variables in Docker?

You can set default values for any environment variables referenced in the Compose file, or used to configure Compose, in an environment file named .env: When you run docker-compose up, the web service defined above uses the image webapp:v1.5.

Why do you use ENV in Docker Compose?

Envionment variable or ENV 1 Basic usages of ENV. If you are running the Image using docker command in terminal or command line, then use argument -e. 2 Set default value for environment variables. 3 Loading environment variables from file. 4 Using .env in docker compose. 5 Use host machine environment variables.

How does the compose file work in Docker?

If the Compose file specifies an image name, the image is tagged with that name, substituting any variables beforehand. See variable substitution. If you change a service’s Dockerfile or the contents of its build directory, run docker-compose build to rebuild it.

Do you need to enable buildkit in Docker?

BuildKit is enabled by default on Docker Desktop, but requires the DOCKER_BUILDKIT=1 environment variable to be set on other platforms. Refer to the Compose CLI environment variables section to learn how to switch between “native build” and “compose build”.