Pass an environment variable to Docker

Question

Here is a particular operation everyone can try:

docker run --env TEST='xxx' ubuntu:14.04 /bin/echo $TEST

That returns an empty string.

Possible duplicate of Docker echo environment variable

Gangaraju
– Gangaraju

2016-08-30 12:53:30 +00:00
Commented Aug 30, 2016 at 12:53 — Gangaraju
– Gangaraju, Commented Aug 30, 2016 at 12:53

ronkot · Accepted Answer · 2016-08-30 13:39:36Z

11

The reason why echoing isn't working is that the $TEST environment variable is substituted on your host side. To postpone the substitution to container side, wrap the echo command with single quotes:

docker run --env TEST='xxx' ubuntu:14.04 sh -c 'echo $TEST'

answered Aug 30, 2016 at 13:39

ronkot

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Oleg Kuralenko · Accepted Answer · 2016-08-30 12:24:26Z

5

You're substituting TEST in your bash instead of your container. Try this command to make sure your variable is passed correctly:

docker run --env TEST='xxx' ubuntu:14.04 /usr/bin/env

answered Aug 30, 2016 at 12:24

Oleg Kuralenko

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