docker-compose 不能使用来自.env 的变量

Question

Docker Compose can't use variables from .env in docker-compose.yml . .env located in the same directory as docker-compose.yml .

.env:

port:3306

docker-compose.yml:

ports:
    - ${port}:${port}

The documentation shows exactly the same example and says that it works

web:
    image: "webapp:${TAG}"

I have error while executing docker-compose up

WARNING: The port variable is not set. Defaulting to a blank string.
ERROR: The Compose file './docker-compose.yml' is invalid because:
services.mariadb.ports is invalid: Invalid port ":", should be [[remote_ip:]remote_port[-remote_port]:]port[/protocol]

How to fix it?

Answer 1

It seems your.env format is wrong. Try:

PORT = 3306

Answer 2

From https://docs.docker.com/compose/env-file/ :

Syntax rules

These syntax rules apply to the.env file:

• Compose expects each line in an env file to be in VAR=VAL format.
• Lines beginning with # are processed as comments and ignored.
• Blank lines are ignored.
• There is no special handling of quotation marks. This means that they are part of the VAL.

in .env , use = instead of :