New Blog submission.

[projectatomic]

New Blog submission.

[jzb]

Hey Dan, made some edits -- thoughts?

I recently published a post on the Red Hat Developer Blog about the Atomic command that we've been working on for the last few months.

The Atomic command (/usr/bin/atomic) is a high-level, coherent entrypoint for Atomic Host systems, and aims to fill in the gaps in Linux container implementations.

One of the first questions I received was about environment substitution. The user wanted to have standard Bash substitutions working with /usr/bin/atomic. Specifically, he wanted to allow substitutions like $PWD/.foobar and --user=$(id -u).

I decided to try this out by creating a simple Dockerfile.

from rhel7
LABEL RUN echo $PWD/.foobar --user=$(id -u)

Then I build the container

docker build -t test .

Then, I'll execute atomic run test

atomic run test
echo 

Looking at the label using docker inspect, I see that building the container dropped the $() content.

So, I'll change the Dockerfile to quote it.

from rhel7
LABEL RUN echo '$PWD/.foobar' '--user=$(id -u)'

Build the container

docker build -t test .

Let's run it again:

atomic run test
echo $PWD/.foobar --user=$(id -u)
/root/test1/.foobar --user=0

Success

Woohoo, it works! If you want to take advantage of environment variables in your LABEL RUN statements, make sure to quote them so they're passed through appropriately.

Have more questions about the atomic command? Leave a comment here, or ask on the [email protected].

[rhatdan]

Looks Awesome.

On 04/21/2015 04:25 PM, jzb wrote:

Hey Dan, made some edits -- thoughts?

I recently published a post on the Red Hat Developer Blog
http://developerblog.redhat.com/2015/04/21/introducing-the-atomic-command
about the Atomic command that we've been working on for the last few
months.

The Atomic http://www.projectatomic.io/docs/usr-bin-atomic/ command
(/usr/bin/atomic) is a high-level, coherent entrypoint for Atomic Host
systems, and aims to fill in the gaps in Linux container implementations.

One of the first questions I received was about environment
substitution. The user wanted to have standard Bash substitutions
working with /usr/bin/atomic. Specifically, he wanted to allow
substitutions like |$PWD/.foobar| and |--user=$(id -u)|.

I decided to try this out by creating a simple Dockerfile.

|from rhel7
LABEL RUN echo $PWD/.foobar --user=$(id -u)
|

Then I build the container

|docker build -t test .
|

Then, I'll execute atomic run test

|atomic run test
echo
|

Looking at the label using |docker inspect|, I see that building the
container dropped the $() content.

So, I'll change the Dockerfile to quote it.

|from rhel7
LABEL RUN echo '$PWD/.foobar' '--user=$(id -u)'
|

Build the container

|docker build -t test .
|

Let's run it again:

|atomic run test
echo $PWD/.foobar --user=$(id -u)
/root/test1/.foobar --user=0
|

Success

Woohoo, it works! If you want to take advantage of environment
variables in your |LABEL RUN| statements, make sure to quote them so
they're passed through appropriately.

Have more questions about the |atomic| command? Leave a comment here,
or ask on the [email protected]
https://lists.projectatomic.io/mailman/listinfo/atomic.

—
Reply to this email directly or view it on GitHub
#109 (comment).

[jzb]

Posted: http://www.projectatomic.io/blog/2015/04/using-environment-substitution-with-the-atomic-command/