Environment Variable Init: HOME

[mitnk]

Using youki as the runtime will missing the env HOME:

$ docker run --rm --runtime youki busybox env
HOSTNAME=efff650756b1
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

Expected (as using runc):

$ docker run --rm busybox env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=2ec2c9640467
HOME=/root

Where is environment variables initialized? I tried but not found in code of the repo.

[utam0k]

@mitnk Thanks for your report. We set the environment variables here.
https://github.com/containers/youki/blob/a8e4003bc67b0eef7fcd59ec89928f7436d5c439/crates/libcontainer/src/process/container_init_process.rs#L415-L419

I couldn't find where the HOME environment variable gets, and I couldn't find it in the runtime-spec.
https://github.com/opencontainers/runtime-spec/blob/main/config.md

I'll do some more research. Do you know anything about it?

[utam0k]

I found that runc has been implemented here.
https://github.com/opencontainers/runc/blob/eddf35e5462e2a9f24d8279874a84cfc8b8453c2/libcontainer/init_linux.go#L309-L398

[utam0k]

Hi, @mitnk. If you have interested in this implementation, I'll leave this implementation to you. Of course, if you don't have time to do it, feel free to ask me to implement it 🙏

[mitnk]

Thanks for the info, I'll have a try :)

[utam0k]

Thanks for the info, I'll have a try :)

Awesome! If you have any questions, please do not hesitate to contact me.

[mitnk]

@utam0k Question 1: I tried adding a syscall.get_pwdir(proc.user().uid()) before setting envs, but the file passwd seems empty (all fields are null-like). So I cannot get the home of user like this. Any ideas?

[mitnk]

Draft PR: #681

[mitnk]

Another question: how to see the logs printed by code like xxx.with_context(|| "some msg"), while using docker run --runtime youki ...? Do we have a doc on this anywhere (I haven't read all the docs yet).

[mitnk]

The file /etc/passwd exists. It's libc::getpwuid_r() returning 2 (No such file/dir?). still checking the reason.

Content of /etc/passwd (via fs::read_to_string() after chroot()):

root:x:0:0:root:/root:/bin/sh
daemon:x:1:1:daemon:/usr/sbin:/bin/false
bin:x:2:2:bin:/bin:/bin/false
sys:x:3:3:sys:/dev:/bin/false
sync:x:4:100:sync:/bin:/bin/sync
mail:x:8:8:mail:/var/spool/mail:/bin/false
www-data:x:33:33:www-data:/var/www:/bin/false
operator:x:37:37:Operator:/var:/bin/false
nobody:x:65534:65534:nobody:/home:/bin/false

[mitnk]

Not sure why, but a re-build fixed the issue. It just works now..

[utam0k]

Another question: how to see the logs printed by code like xxx.with_context(|| "some msg"), while using docker run --runtime youki ...? Do we have a doc on this anywhere (I haven't read all the docs yet).

It is hard to see the log while using docker. If you want to see the log, it would be good to use the youki directory without using docker.

[utam0k]

@utam0k Question 1: I tried adding a syscall.get_pwdir(proc.user().uid()) before setting envs, but the file passwd seems empty (all fields are null-like). So I cannot get the home of user like this. Any ideas?

Did you resolve this question by yourself?

[mitnk]

Yes, resolved.

[mitnk]

fixed in #681 Thanks!

[utam0k]

@mitnk Nice work!