docker-compose not setting environment variables

That's normal

docker-compose only sets the environment variables specified in the environment directive in the docker-compose.yaml file during the run phase of the container, and not during the build phase.

So if you do docker-compose run --entrypoint "/bin/bash" redis -c env you will be able to see your env variables.

If you want to set variables inside your Dockerfile (to be able to see them during the build phase) you can add inside your dockerfile before your RUN env:

ENV FOO bar

This is because you were using environment when (I guess) you wanted to use args inside the build block:

redis:
    build: 
      context: ../storage/redis
      args:
        - FOO: 'bar'
      ports:
        - "6379:6379"

And FUN would be defined as follows (in your Dockerfile):

FROM redis:2.6

RUN mkdir -p /var/redis && chown -R redis:redis /var/redis

# Read FUN from (build) arguments 
# (may define a default: ARG FUN='wow')
ARG FUN

# Define env variable FUN with value from ARG
ENV FUN=$FUN

RUN echo '-------------- env ---------------'
RUN env

COPY redis.conf /usr/local/etc/redis/redis.conf
EXPOSE 6379
ENTRYPOINT ["redis-server", "/usr/local/etc/redis/redis.conf"]

The environment block is used to define variables for the running container (when docker-compose up, NOT when docker-compose build).

Similar answer to a similar question, may be of interest:

• https://stackoverflow.com/a/74315994/687896

Well I have tested and found following solutions for docker compose with env file or without env file. I will show you two different approach

Lets say you have following docker compose yml file

version: '3.8'
services:
db:
image: postgres:13
volumes:
 - "./volumes/postgres:/var/lib/postgresql/data"
ports:
 - "5432:5432"
env_file: docker.env

Now you need to setup the postgres variable in a file called docker.env. Remember you need to keep the docker_compose.yml file and docker.env file in same folder. Next, In the docker.env file you need to have the database variable and value like this:

POSTGRES_USER=postgres
POSTGRES_PASSWORD=postgres
POSTGRES_DB=myapp_db

Now hit docker-compose up . It should work. Lets say now you dont like to specify the env file name in the docker-compose.yml file. So you have to write docker-compose.yml file like this:

version: '3.8'
services:
db:
  image: postgres:13
  volumes:
    - "./volumes/postgres:/var/lib/postgresql/data"
  ports:
    - "5432:5432"
  environments:
     - POSTGRES_USER=${PGU}
     -POSTGRES_PASSWORD=${PGP}
     -POSTGRES_DB=${PGD}

Now your docker.env file should look like this:

PGU=postgres
PGP=postgres
PGD=myapp_db

now hit docker-compose --env-file docker.env up

you are good to go.

TLDR: If you need to use environments, use an ENV file instead of placing it into a compose file. When placing environment variables in a docker-compose file (list of environment variables) and those variables are referencing each other, the docker-loader does not correctly join those correctly.

Explanation:

The long and short is, the Environment variables when placed in a .env file are evaluated BEFORE being provided to the running docker environment. This allows for specific environment variables to be made dynamically (see in my example below of the connection string leveraging the environment variables in the ENV file).

Use this Instead

version: '3.8'
services:
db:
image: postgres:13
volumes:
 - "./volumes/postgres:/var/lib/postgresql/data"
ports:
 - "5432:5432"
env_file: docker.env

docker.env file contains:

   ASPNETCORE_ENVIRONMENT=Test
    DATABASE_USER=lawguy007
    DATABASE_PASSWORD=myPasswordIsBoring
    DATABASE_SERVER=192.168.1.25    
    ConnectionStrings__DefaultConnection=Server="${DATABASE_SERVER}";Include Error Detail=true;Database=threatlists;User Id=${DATABASE_USER};Password=${DATABASE_PASSWORD}