Audio/sound (ALSA) in guix environment --container

Audio/sound (ALSA) in guix environment --container

[Pierre Neidhardt]

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Hi!

I'm trying to run an graphical application with audio in a Guix
environment.

So far:

--8<---------------cut here---------------start------------->8---
guix environment --container \
  --share=/tmp/.X11-unix/ \
  --share=/dev/snd \
  --ad-hoc foo coreutils -- \
  env DISPLAY=$DISPLAY foo "$@"
--8<---------------cut here---------------end--------------->8---

I get this error:

--8<---------------cut here---------------start------------->8---
ALSA lib pcm_direct.c:1943:(snd1_pcm_direct_parse_open_conf) The field ipc_gid must be a valid group (create group audio)
--8<---------------cut here---------------end--------------->8---

I though --share=/dev/snd would help, but I don't think that's useful.
I tried creating the "audio" group in the container or adding the user
to the group, to no avail:

--8<---------------cut here---------------start------------->8---
> guix environment -C --ad-hoc coreutils shadow 
ambrevar@bababa . [env]# groups
groups: cannot find name for group ID 0
0 groups: cannot find name for group ID 65534
65534
ambrevar@bababa . [env]# groupadd foo
groupadd: PAM: Critical error - immediate abort
--8<---------------cut here---------------end--------------->8---

Can anyone get ALSA to work in Guix containers?

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Re: Audio/sound (ALSA) in guix environment --container

[Ludovic Courtès]

Hello!

Pierre Neidhardt <mail@ambrevar.xyz> skribis:

> I'm trying to run an graphical application with audio in a Guix
> environment.
>
> So far:
>
> guix environment --container \
>   --share=/tmp/.X11-unix/ \
>   --share=/dev/snd \
>   --ad-hoc foo coreutils -- \
>   env DISPLAY=$DISPLAY foo "$@"
>
>
> I get this error:
>
> ALSA lib pcm_direct.c:1943:(snd1_pcm_direct_parse_open_conf) The field ipc_gid must be a valid group (create group audio)
>
>
> I though --share=/dev/snd would help, but I don't think that's useful.
> I tried creating the "audio" group in the container or adding the user
> to the group, to no avail:
>
>> guix environment -C --ad-hoc coreutils shadow 
> ambrevar@bababa . [env]# groups
> groups: cannot find name for group ID 0
> 0 groups: cannot find name for group ID 65534
> 65534

Commit 952afb6f8c209692e52f9561965ee39e143e1d88 changes ‘guix
environment’ so that it creates /etc/group, using the brand new (gnu
build accounts) module.

Now ‘id’ and ‘groups’ work fine in containers.

Does it solve the specific problem you were having?  Maybe there are
other things that would need to be done, dunno.

I’m thinking we should change ‘guix environment -C’ to map to a UID
other than zero, at least by default.  When developing code, some tools
may behave differently when running under UID 0 and that’s rarely what
we need I think.  Thoughts?

Ludo’.

Re: Audio/sound (ALSA) in guix environment --container

[Ricardo Wurmus]

Ludovic Courtès <ludo@gnu.org> writes:

> I’m thinking we should change ‘guix environment -C’ to map to a UID
> other than zero, at least by default.  When developing code, some tools
> may behave differently when running under UID 0 and that’s rarely what
> we need I think.  Thoughts?

I agree.  Defaulting to UID 0 is not good.  (“conda” is an example of
one application that has very different behaviour when it thinks it is
running as root.)

--
Ricardo

Re: Audio/sound (ALSA) in guix environment --container

[Pierre Neidhardt]

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I've just "guix pull"ed and I get the following:

--8<---------------cut here---------------start------------->8---
> guix environment --container --ad-hoc coreutils shadow 
# id
uid=0(ambrevar) gid=0(users) groups=0(users),65534(overflow)
# groupadd audio
groupadd: PAM: Critical error - immediate abort
# useradd foo
useradd: PAM: Critical error - immediate abort
--8<---------------cut here---------------end--------------->8---

Any idea where to go from here?

Ricardo Wurmus <rekado@elephly.net> writes:

> I agree.  Defaulting to UID 0 is not good.  (“conda” is an example of
> one application that has very different behaviour when it thinks it is
> running as root.)

What about defaulting to 1000?  It's rather common, so I guess that
would be anonymous enough and "just work".

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Re: Audio/sound (ALSA) in guix environment --container

[Ricardo Wurmus]

Pierre Neidhardt <mail@ambrevar.xyz> writes:

> I've just "guix pull"ed and I get the following:
>
> --8<---------------cut here---------------start------------->8---
>> guix environment --container --ad-hoc coreutils shadow 
> # id
> uid=0(ambrevar) gid=0(users) groups=0(users),65534(overflow)
> # groupadd audio
> groupadd: PAM: Critical error - immediate abort
> # useradd foo
> useradd: PAM: Critical error - immediate abort
> --8<---------------cut here---------------end--------------->8---
>
> Any idea where to go from here?

I suppose /etc/pam.d/ also needs to be in the container.

> Ricardo Wurmus <rekado@elephly.net> writes:
>
>> I agree.  Defaulting to UID 0 is not good.  (“conda” is an example of
>> one application that has very different behaviour when it thinks it is
>> running as root.)
>
> What about defaulting to 1000?  It's rather common, so I guess that
> would be anonymous enough and "just work".

Would it make sense to map the current user’s UID into the container
instead of using a fixed UID?

-- 
Ricardo

Re: Audio/sound (ALSA) in guix environment --container

[Pierre Neidhardt]

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Ricardo Wurmus <rekado@elephly.net> writes:

> I suppose /etc/pam.d/ also needs to be in the container.

Tried it, same error.

>> What about defaulting to 1000?  It's rather common, so I guess that
>> would be anonymous enough and "just work".
>
> Would it make sense to map the current user’s UID into the container
> instead of using a fixed UID?

We have a "--user" option, so we could use the current user's UID when
--user is not specified, 1000 otherwise.
Or better: add a --uid CLI option.

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Re: Audio/sound (ALSA) in guix environment --container

[Ricardo Wurmus]

Pierre Neidhardt <mail@ambrevar.xyz> writes:

> Ricardo Wurmus <rekado@elephly.net> writes:
>
>> I suppose /etc/pam.d/ also needs to be in the container.
>
> Tried it, same error.
>
>>> What about defaulting to 1000?  It's rather common, so I guess that
>>> would be anonymous enough and "just work".
>>
>> Would it make sense to map the current user’s UID into the container
>> instead of using a fixed UID?
>
> We have a "--user" option, so we could use the current user's UID when
> --user is not specified, 1000 otherwise.
> Or better: add a --uid CLI option.

I can see confusion coming from the existence of both “--user” and
“--uid”.  Maybe “--user” could take an optional argument, with the
default being the current user.  Without “--user” we’d use UID 1000.

What do you think?

--
Ricardo

Re: Audio/sound (ALSA) in guix environment --container

[Ludovic Courtès]

Ricardo Wurmus <rekado@elephly.net> skribis:

> Pierre Neidhardt <mail@ambrevar.xyz> writes:
>
>> Ricardo Wurmus <rekado@elephly.net> writes:
>>
>>> I suppose /etc/pam.d/ also needs to be in the container.
>>
>> Tried it, same error.
>>
>>>> What about defaulting to 1000?  It's rather common, so I guess that
>>>> would be anonymous enough and "just work".
>>>
>>> Would it make sense to map the current user’s UID into the container
>>> instead of using a fixed UID?
>>
>> We have a "--user" option, so we could use the current user's UID when
>> --user is not specified, 1000 otherwise.
>> Or better: add a --uid CLI option.
>
> I can see confusion coming from the existence of both “--user” and
> “--uid”.  Maybe “--user” could take an optional argument, with the
> default being the current user.  Without “--user” we’d use UID 1000.

Currently, without --user, we keep the current user’s name.  So it would
actually be consistent to inherit its UID as well.  And with ‘--user’,
we’d use the given user name and UID 1000.  (Essentially what Pierre
proposed above.)

Thoughts?  :-)

Ludo’.

Re: Audio/sound (ALSA) in guix environment --container

[Ricardo Wurmus]

Ludovic Courtès <ludo@gnu.org> writes:

> Ricardo Wurmus <rekado@elephly.net> skribis:
>
>> Pierre Neidhardt <mail@ambrevar.xyz> writes:
>>
>>> Ricardo Wurmus <rekado@elephly.net> writes:
>>>
>>>> I suppose /etc/pam.d/ also needs to be in the container.
>>>
>>> Tried it, same error.
>>>
>>>>> What about defaulting to 1000?  It's rather common, so I guess that
>>>>> would be anonymous enough and "just work".
>>>>
>>>> Would it make sense to map the current user’s UID into the container
>>>> instead of using a fixed UID?
>>>
>>> We have a "--user" option, so we could use the current user's UID when
>>> --user is not specified, 1000 otherwise.
>>> Or better: add a --uid CLI option.
>>
>> I can see confusion coming from the existence of both “--user” and
>> “--uid”.  Maybe “--user” could take an optional argument, with the
>> default being the current user.  Without “--user” we’d use UID 1000.
>
> Currently, without --user, we keep the current user’s name.  So it would
> actually be consistent to inherit its UID as well.  And with ‘--user’,
> we’d use the given user name and UID 1000.  (Essentially what Pierre
> proposed above.)

Excellent, this sounds good.

-- 
Ricardo

Re: Audio/sound (ALSA) in guix environment --container

[Ludovic Courtès]

Hello!

Ricardo Wurmus <rekado@elephly.net> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:

[...]

>> Currently, without --user, we keep the current user’s name.  So it would
>> actually be consistent to inherit its UID as well.  And with ‘--user’,
>> we’d use the given user name and UID 1000.  (Essentially what Pierre
>> proposed above.)
>
> Excellent, this sounds good.

Done in commit 1ccc0f807d3f22fa9ade1c607c112e04df833a72.

Ludo’.

Re: Audio/sound (ALSA) in guix environment --container

[Pierre Neidhardt]

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Nice, just tried it and it's working.
It's also able to start programs I would not start before, so great
success!

I'm still not able to play any sound though.  Anyone?

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Re: Audio/sound (ALSA) in guix environment --container

[Ludovic Courtès]

Hello,

Ricardo Wurmus <rekado@elephly.net> skribis:

> Would it make sense to map the current user’s UID into the container
> instead of using a fixed UID?

From a reproducibility viewpoint, I’d find it nicer to use a fixed UID
(it can still be mapped to the user’s name anyway.)

We could make it configurable if necessary.  WDYT?

Ludo’.