Export environment docker variable to file

Question

I have very a simple docker file:

FROM tomcat:7.0
RUN echo $HOST_IP > /opt/serverIP

When I run my image (my-server) with follow command the file /opt/serverIP exists and it is empty:

docker run -e HOST_IP='172.16.1.1' -t my-server cat /opt/serverIP

How to write my environment value into a temporary file?

My docker version: Docker version 1.12.1, build 23cf638
This is my machine info:

Kernel Version: 4.4.0-36-generic
Operating System: Ubuntu 16.04 LTS
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 7.703 GiB

David M. Karr · Accepted Answer · 2016-09-02 15:17:07Z

3

I believe you're confusing build-time variables with run-time variables. The "RUN" command is essentially executed at build time. Your "HOST_IP" value is supplied at run time.

The "CMD" instruction, however, is executed at run time. To approximately do what you're trying to do, define a "CMD" that writes $HOST_IP to the file. use "docker run" to run the image, and then use "docker exec" to verify the contents of the file.

answered Sep 2, 2016 at 15:17

David M. Karr

15.3k24 gold badges117 silver badges221 bronze badges

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

3 Comments

FabryProg Over a year ago

Thanks, i change my docker file and my image is running. But the file not exists!

David M. Karr Over a year ago

You'd have to update your post with exactly what you have now. It might also help to see the "docker build" output.

FabryProg Over a year ago

I risolve it using an sh script. Thanks and King regards

Collectives™ on Stack Overflow

Export environment docker variable to file

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related