Declare env variable which value include space for docker/docker-compose

Lets see the result running the following compose file:

version: "3"

services:
    service:
        image: alpine
        command: env
        env_file: env.conf

env.conf:

TEST_VAR1=The value
TEST_VAR2="The value2"

docker-compose up Result:

service_1 | PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
service_1  | TEST_VAR2="The value2"
service_1  | TEST_VAR1=The value
service_1  | HOME=/root

Therefore, it is legal to have spaces in the env value.

You can escape the space with a \:

TEST_VAR=The\ value

Edit: This is how I pass them when starting the container (i.e. docker run -e TEST_VAR=The\ value hello-world). If you're using docker-compose or an env file, see the answer by @yamenk.