Compose: WARNING: The X variable is not set. Defaulting to a blank string.

[a1exus]

My environment:

# docker-compose version
docker-compose version 1.8.1, build 878cff1
docker-py version: 1.10.3
CPython version: 2.7.12
OpenSSL version: OpenSSL 1.0.2h  3 May 2016
# 

I'm seeing following _WARNING_ message:

# docker-compose ps
WARNING: The ELK variable is not set. Defaulting to a blank string.
    Name              Command          State                    Ports                   
---------------------------------------------------------------------------------------
nginx_nginx_1   nginx -g daemon off;   Up      0.0.0.0:443->443/tcp, 0.0.0.0:80->80/tcp 
#

Per Environment variables in Compose - Docker:

• Substituting environment variables in Compose files

# grep ELK docker-compose.yaml 
        gelf-address: "udp://${ELK}:12201"
# 

• The “env_file” configuration option

# grep -A1 env_file docker-compose.yaml 
    env_file:
      - docker-compose.env
# grep ELK docker-compose.env 
ELK=172.17.0.2
# 

Please advise.

[shin-]

You need to escape the variable if you want it to be expanded inside the container, using a double-dollar sign ($${ELK}).
If however, you want it to be interpreted on your host, the $ELK needs to be defined in your environment or in the .env file. The env_file option defines environment variables that will be available inside the container only.

[a1exus]

@shin-

I'm trying to implement following:

• Substituting environment variables in Compose files.
• The “env_file” configuration option.

[rloth]

It's not intuitive to me that the file specified by the "env_file" directive acts differently than the ".env" file...

However @shin- 's comment made it clear to me... the ".env" file's vars are available at docker-compose stage whereas all other env vars set via env_file or env directive are only available within the container... ok

[imaia]

However @shin- 's comment made it clear to me... the ".env" file's vars are available at docker-compose stage whereas all other env vars set via env_file or env directive are only available within the container... ok

That feels a lot like a bug. There shouldn't be "too specific" behavior. It only confuses people.

[Joshfindit]

Found this issue first in the search for a resolution, and ended up understanding then solving it with the info here: http://staxmanade.com/2016/05/how-to-get-environment-variables-passed-through-docker-compose-to-the-containers/

Specifically;
set the variable in ./.env, which makes it available to substitute in docker-compose.yml

EXTERNAL_PORT=8000

then in docker-compose.yml, pass it through to the container with:

environment:
      - EXTERNAL_PORT=${EXTERNAL_PORT}

edit: added ./ to make it clear we are not talking about <file>.env

[a1exus]

@Joshfindit that is EXACTLY like in my comment and yet this isn't working for me, hence new issue..

[Joshfindit]

@a1exus I don't see where you're mentioning ./.env in your comments.
What is the content of your ./.env file?

[a1exus]

@Joshfindit at the very end of my comment:

# grep ELK docker-compose.env 
ELK=172.17.0.2
# 

[Joshfindit]

@a1exus ./docker-compose.env != ./.env

[shin-]

To reiterate what I wrote earlier in this thread:

• The environment and env_file sections of the Compose file declare variables that will be available inside the container.
• Variables written using the $VAR or ${VAR} syntax inside the Compose file are replaced by the value found on the host machine (i.e. the machine you're executing docker-compose from) at the time of execution. They're found either in the OS's environment or the statically named .env file.
• If variable substitution is not desired, one should use the double-dollar-sign notation ($$VAR or $${VAR}) to escape the sequence.

[a1exus]

Per @Joshfindit I've tried with .env and everything works like a charm! Thank you!

[oojacoboo]

@shin- can you explain what I'm missing here?

Variables written using the $VAR or ${VAR} syntax inside the Compose file are replaced by the value found on the host machine (i.e. the machine you're executing docker-compose from) at the time of execution.

services:
  nginx:
    user: ${UID}

I get this: WARNING: The UID variable is not set. Defaulting to a blank string.

However:

[jacob:.../foo]$ echo $UID
501

[shin-]

@oojacoboo $UID is not an environment variable, it's a shell variable:

$ echo $UID
1000
$ printenv | grep UID  # no output
$

See #2380

[oojacoboo]

@shin- was just actually about to update my comment as I noticed the same thing - thanks. And thanks for the issue link - perfect.

[jibusayone]

I managed to find a solution! I used the env_file setting itself, and defined the file variables.env within the same line. And it worked like a charm!

Here is how my docker-compose.yml looks like:

services:
  web:
    env_file: variables.env

[a1exus]

you can also use _.env_ in root of your project it does same...

[sodik82]

just for future googlers. my problem was with environment variables not being passed through sudo (e.g. on Ubuntu). Working solution:

sudo -E docker-compose up -d

[alexei-developer]

Hello, I am problem with set variable in yaml file:
docker-compose build master
WARNING: The CI_ARTEFACTS_HOSTPATH variable is not set. Defaulting to a blank string.
Building master
... (cut log)

I am use:

      CI_ARTEFACTS_HOSTPATH: '/ci'
      CI_ARTEFACTS_HOSTPATH: "/ci"
      - CI_ARTEFACTS_HOSTPATH=/ci

docker-compose --version
docker-compose version 1.24.0-rc1, build 0f3d4dda

docker-compose.yaml:

version: "3.4"
services:
  master:
    environment:
      CI_ARTEFACTS_HOSTPATH: '/ci'
    build:
      context: master
      network: host
    image: buildbot-master
    command: buildbot start --nodaemon master
    ports:
      - 8010:8010
      - 9989:9989
    volumes:
      - ${CI_ARTEFACTS_HOSTPATH}:/ci/artefacts

[agolaszewski]

@alexei-developer
Have you solved this issue? I have the same problem

[Tymek]

This example may help if you would like to provide default value in docker-compose env:

Use "${ENV_VAR:-defaultValue}"

    environment:
      HASURA_GRAPHQL_DATABASE_URL: "${HASURA_GRAPHQL_DATABASE_URL:-postgres://postgres:@postgres:5432/postgres}"

Using .env can override default url.

[joelnbl]

sudo service redis-server stop -> sudo systemctl stop docker ->sudo systemctl start docker

[zlydenko]

Still have this issue, passing variables like this docker-compose --env-file /etc/.env up -d and receiving Error while attempting to convert service.dev.ports.published to appropriate type