Docker-compose not passing environment variable to container

Question

I am using Docker 17.04.0-ce, build 4845c56 with docker-compose 1.12.0, build b31ff33 on Ubuntu 16.04.2 LTS. I simply want to pass an environment variable and display it from my script running in a container. I am doing this according to the documentation https://docs.docker.com/compose/compose-file/#environment . The problem is that the variable is not passed to the container.

My docker-compose.yml file:

env-file-test:
  build: .
  dockerfile: Dockerfile
  environment:
    - DEMO_VAR

My Dockerfile:

FROM alpine
COPY docker-start.sh /
CMD ["/docker-start.sh"]

And the docker-start.sh file:

#!/bin/sh
echo "DEMO_VAR Var Passed in: $DEMO_VAR"

I try to set the variable in my current terminal session and pass it to the container:

$ export DEMO_VAR=aabbdd
$ echo $DEMO_VAR
aabbdd
$ sudo docker-compose up
Starting envfiletest_env-file-test_1
Attaching to envfiletest_env-file-test_1
env-file-test_1  | DEMO_VAR Var Passed in: 
envfiletest_env-file-test_1 exited with code 0

So you can see that the variable DEMO_VAR is empty!

I also tried using variables in docker-compose.yml like this: DEMO_VAR=${DEMO_VAR} but then when I run sudo docker-compose up, I get a warning: "WARNING: The DEMO_VAR variable is not set. Defaulting to a blank string.".

What am I doing wrong? What should I do to pass the variable to the container?

Community · Accepted Answer · 2017-05-23 12:02:37Z

14

I found a solution. Answering my own question...

The problem was with the sudo command. It turned out that it does not pass environment variables by default. There are some possible solutions:

Use sudo -E. Demo:

$ export DEMO_VAR=aabbdd
$ echo $DEMO_VAR
aabbdd
$ sudo -E docker-compose up
env-file-test_1  | DEMO_VAR Var Passed in: aabbdd

Use sudo VAR=value:

sudo DEMO_VAR=$DEMO_VAR docker-compose up

Add environment variables to the sudoers file (https://stackoverflow.com/a/8636711)
Use docker without sudo (https://askubuntu.com/questions/477551/how-can-i-use-docker-without-sudo)

edited May 23, 2017 at 12:02

CommunityBot

11 silver badge

answered Apr 21, 2017 at 7:09

JustAC0der

3,2813 gold badges35 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

user2915097 · Accepted Answer · 2017-04-21 06:31:10Z

-2

you should use ENV in your Dockerfile, and avoid export.

See the doc

https://docs.docker.com/engine/reference/builder/#env

answered Apr 21, 2017 at 6:31

user2915097

32.4k6 gold badges61 silver badges62 bronze badges

5 Comments

JustAC0der Over a year ago

Could you give an example how to use ENV to pass the environment variable from the current terminal?

user2915097 Over a year ago

You use ENV in your Dockerfile, with a line such as ENV demo_var aabbdd or other syntax ENV demo_var=aabbdd

JustAC0der Over a year ago

But I don't want to set the value in the Dockerfile. The DEMO_VAR is only an example, but in a real-world project it can contain a server-specific configuration variable or even a password. I want to pass it from the current session (current terminal).

JustAC0der Over a year ago

"The ARG instruction defines a variable that users can pass at build-time"... but I want to pass a variable at run-time, not build-time. BTW: I've just found a solution to my problem. I posted it as an answer.

user2915097 Over a year ago

at run time, you have docker run -e see the doc docs.docker.com/engine/reference/run/#env-environment-variables

Collectives™ on Stack Overflow

Docker-compose not passing environment variable to container

2 Answers 2

Comments

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related