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

[szxp]

I'm seeing the following WARNING message:

My docker-compose.yml file:

version: '2'
services:
  web:
    image: alpine
    environment:
      DB_DEV: ${DB_DEV}

I'm running the following commands:

$ export DB_DEV=xxx
$ env | grep DB_DEV
DB_DEV=xxx
$ sudo docker-compose config
WARNING: The DB_DEV variable is not set. Defaulting to a blank string.
services:
  web:
    environment:
      DB_DEV: ''
    image: alpine
version: '2.0'

My environment:

$ sudo docker version
Client:
 Version:      17.06.0-ce
 API version:  1.30
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:20:04 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.06.0-ce
 API version:  1.30 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:18:59 2017
 OS/Arch:      linux/amd64
 Experimental: false
$ sudo docker-compose version
docker-compose version 1.14.0-rc2, build 24dae73
docker-py version: 2.3.0
CPython version: 2.7.13
OpenSSL version: OpenSSL 1.0.1t  3 May 2016
$ uname -a
Linux laptop 3.16.0-4-amd64 #1 SMP Debian 3.16.43-2 (2017-04-30) x86_64 GNU/Linux
$ echo $BASH_VERSION
4.3.30(1)-release

I use Debian 8.

[shin-]

sudo changes the context of execution, so the variable you set before entering it isn't accessible.

[szxp]

Thank you. I didn't know that. Adding -E to the sudo command solved the problem:

$ export DB_DEV=xxx
$ env | grep DB_DEV
DB_DEV=xxx
$ sudo -E docker-compose config
services:
  web:
    environment:
      DB_DEV: xxx
    image: alpine
version: '2.0'