Understanding environment variables

LXD
1

Hi,

Based on reading the docs and experimentation, environment variables are only applied to the root user in the container. Is that correct?

For example, if I have something like this in my profile:

config:
  environment.BAR: bar
  environment.FOO: foo

I can see these in the root user env with:

$ lxc exec c1 -- env

However, if I look at a different user env with:

$ lxc exec c1 -- sudo --user ubuntu env

FOO and BAR are not shown. If I use the -E arg in the sudo call above, they are shown.

Is that a correct understanding? Is there a way in a profile to apply the environment to other users or should that be done using a different mechanism during container creation?

Thanks.
Rob

1 Like
2

Interesting question, I would also like to know the answer.

As alternative you can probably use cloud-init.

3

That’s good idea. I put this cloud-init in the profile and removed the environment settings:

write_files:
- path: /etc/environment
  content: |
    FOO="FOO"
    BAR="BAR"
  append: true

Now it seems to work in the opposite way in that lxc exec c2 -- env doesn’t have the variables while lxc exec c2 -- sudo --user ubuntu env does.

I can make that work but I’m still fuzzy on the “best” way to do this with LXD.

Thanks for the reply.
Rob

4

sudo indeed strips environment variables by default, so this is expected.

5

There are several ways to get a shell into a container, https://blog.simos.info/using-command-aliases-in-lxd-to-exec-a-shell/

In a nutshell,

$ lxc ubuntu env
ubuntu@env:~$ env | grep Env
EnvFromConfigEnvironment=enabled
ubuntu@env:~$ logout
$ lxc shell env
root@env:~# env | grep Env
EnvFromCloudConfig=enabled
root@env:~# logout
$ lxc exec env -- sudo --user ubuntu --login
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@env:~$ env | grep Env
EnvFromCloudConfig=enabled
ubuntu@env:~$ logout

Therefore, have a look at my post and the lxc ubuntu alias. In effect, it does lxc exec without the need for sudo. It uses the new options in lxc exec to get a shell into the container.

1 Like
6

Thanks for the quick and helpful replies. I’ve got a better understanding now. :slightly_smiling_face: