How do you create a Docker Compose file that is parametrized using environment variables?
Experience Level: Junior
Tags: Docker Compose
Answer
To write an environment variable value to a Docker Compose file, use the ${ENVIRONMENT_VARIABLE_NAME} syntax.
If the environment variable exists, the placeholder will be replaced by the value of the environment variable when the Docker Compose file is used.
version: "3.4"
services:
my-service:
image: "webapp:${TAG}"
Note that the environment variables must reside in a file .env or other file that is passed to docker using --env-file parameter.
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