CODEWITHSUNDEEP
dockerdocker-composeenvironment-variables
user4058302
user4058302

Reputation:

docker-compose does not initalize container environment variables

I am trying to execute simple code.

docker-compose.yml

version: '3.7'

services:
  test-environment:
    image: alpine:3.9
    environment: 
      VAR1: 'variable 1'
      VAR2: '222'
    command: echo variable1 = $VAR1; variable2 = $VAR2

Expected behavior: to see in output 

variable1 = variable 1; variable2 = 222

But after

docker-compose up

i got next:

WARNING: The VAR1 variable is not set. Defaulting to a blank string.
WARNING: The VAR2 variable is not set. Defaulting to a blank string.
Recreating project_test-environment_1 ... done
Attaching to project_test-environment_1
test-environment_1  | variable1 = ; variable2 =
project_test-environment_1 exited with code 0

It seems like environment variables were not initialized. Using alternative syntax

environment:
 - VAR1='variable 1'
 - VAR2=222

given the same result too.

docker info output:

Containers: 3
Running: 0
Paused: 0
Stopped: 3
Images: 5
Server Version: 18.09.2
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file local logentries 
 splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 9754871865f7fe2f4e74d43e2fc7ccd237edcbce
runc version: 09c8266bf2fcf9519a651b04ae54c967b9ab86ec
init version: fec3683
Security Options:
 seccomp
 Profile: default
Kernel Version: 4.9.125-linuxkit
Operating System: Docker for Windows
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 973.8MiB
Name: linuxkit-00155d694b07
ID: NA32:YPM3:D5GL:JQBM:H4BN:LE2B:4HLN:5B4A:AI7T:6SDS:LSVZ:P74L
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: 22
 Goroutines: 47
 System Time: 2019-05-14T08:44:02.5767035Z
 EventsListeners: 1
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false
Product License: Community Engine

Does anyone has any ideas to solve problem?

P.S. Sorry for my English.

Upvotes: 1

Views: 1948

Answers (2)

Akshay barahate
Akshay barahate

Reputation: 785

enter image description here

version: '3'
services:
  test-environment:
    image: alpine:3.9
    environment:
      VAR1: 'variable 1'
      VAR2: '222'
    command: '/bin/sh -c "echo $$VAR1 $$VAR2"'

Important points:

  1. variable-substitution
  2. docker inspect command to check if env variables are configured properly for that container.
  3. I used version 3 as my docker-compose do not support the version you are using.
  4. The .env file feature only works when you use the docker-compose up command and does not work with docker stack deploy.
  5. You can use a $$ (double-dollar sign) when your configuration needs a literal dollar sign. This also prevents Compose from interpolating a value, so a $$ allows you to refer to environment variables that you don’t want processed by Compose.
  6. If you forget and use a single dollar sign ($), Compose interprets the value as an environment variable and warns you:

WARNING: The VAR1 variable is not set. Defaulting to a blank string. WARNING: The VAR2 variable is not set. Defaulting to a blank string.

Upvotes: 2

Efrat Levitan
Efrat Levitan

Reputation: 5632

the environment option specifies which vars will be passed to the container. they are not available outside in the docker-compose file. if you need env vars for your docker-compose file, create on the same directory a .env file:

#.env
VAR1=variable1
VAR2=222

and now it should work for docker-compose up

note

remove the environment option from the docker-compose - unless you need the vars inside the container, it makes no sense.

Upvotes: 1

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