Re: Help with pasta usage

Re: Help with pasta usage

[Stefano Brivio]

Hi Ayon,

On Sat, 10 May 2025 21:26:29 -0230
Ayon T <sanroz.mozan13@gmail.com> wrote:

> Hi,
> 
> I've been using pasta as a network driver for rootless docker and I've been
> running into a couple of issues for a while now. I hope this is where I can
> find some help troubleshooting.
> 
> The issue is that when I use pasta as the network driver as opposed to
> slirp4netns, I'm unable to access the internet through rootless docker or
> use ping (or traceroute) through its containers. So if I run "docker pull
> <image-name>" I get a timeout error:
> 
> > Using default tag: latest  
> Error response from daemon: Get "https://registry-1.docker.io/v2/": dial
> tcp: lookup registry-1.docker.io on 10.0.2.3:53: read udp 169.254.2.1:58905
> ->10.0.2.3:53: i/o timeout  
> 
> I'm running pasta version 0.0~git20250217.a1e48a0-1 on Ubuntu 24.04.2 LTS
> with docker v27.3.1 build ce12230.

I suspect you might be hitting this:

  https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/2077158

...which is fixed on Ubuntu 24.10 and later versions. As a workaround,
I guess you can create the AppArmor profile for pasta manually, from:

  https://passt.top/passt/tree/contrib/apparmor/usr.bin.pasta

or set /proc/sys/kernel/unprivileged_userns_apparmor_policy to 0, see
also:

  https://github.com/kubevirt/kubevirt/issues/12333

Let me know if you still hit the issue.

-- 
Stefano

Re: Help with pasta usage

[Stefano Brivio]

On Mon, 12 May 2025 12:18:17 -0230
Ayon T <sanroz.mozan13@gmail.com> wrote:

> Hi,
> 
> Thanks for responding back to me. I was trying these solutions, when I
> realised that my /etc/apparmor.d/ directory already contains usr.bin.pasta.
> I believe this is because I downloaded the latest package from the
> launchpad.

...wait, so it's not 0.0~git20250217.a1e48a0-1 anymore? What version of
passt are you using now?

And what version of rootlesskit are you running? Does it contain this
fix:

  https://github.com/rootless-containers/rootlesskit/pull/458

it's not directly related to your issue, but it changes the behaviour
significantly.

I don't remember how you would pass pasta options through moby /
rootlesskit, but ideally you should try running pasta with --debug and
--log-file. Another important bit of information would be if container
connectivity works with an existing container (on 'docker run', not
'docker pull'), and, if it doesn't, whether pasta is running (check
with 'ps ax') while the container is running.

-- 
Stefano

Re: Help with pasta usage

[Stefano Brivio]

Hi Ayon,

On Tue, 20 May 2025 12:09:46 -0230
Ayon T <sanroz.mozan13@gmail.com> wrote:

> Hi,
> 
> I'm sorry for the delayed response. No, I am still using
> 0.0~git20250217.a1e48a0-1. I just meant that I had not used apt for
> installing passt.

...where did you take that package from, though? If it's something like
alvistack (https://github.com/alvistack/passt-top-passt/), there might
be other patches or modified / missing AppArmor profiles, and I can't
really look into that as well (I already maintain official packages, at
least for Debian).

> I had an upgrade planned to Ubuntu 24.10 and after that upgrade, my
> connections to port 53 are being refused when I'm using pasta, leaving me
> unable to use a DNS resolver. I'm not sure why this is. It works fine with
> the default network driver.
> 
> This is not the issue I contacted you with and that's why I'm trying to
> figure out why this is happening myself (albeit with little luck).

I would suggest to start passing the --pcap option to pasta, say:

  podman run --net=pasta:--pcap,/tmp/port53.pcap ...

and then have a look at the resulting packet capture (with Wireshark /
tshark, for example).

As we keep fixing bugs, and we fixed quite a lot of things with UDP
flows since February, an updated package, or even a build from source,
(git clone git://passt.top && cd passt && make && sudo make install)
might be worth a try.

It takes a few seconds to build / install, and can be removed cleanly
with 'sudo make uninstall'.

-- 
Stefano

Re: Help with pasta usage

[Stefano Brivio]

On Fri, 23 May 2025 00:51:25 -0230
Ayon T <sanroz.mozan13@gmail.com> wrote:

> I know you have been asking me to run pasta with arguments with docker, but
> I'm not sure how to do this (pardon my inexperience). I use an
> override.conf file to set the default network and port driver of docker,
> and that's how I use pasta with docker. I have tried looking up how to do
> it in a different way that gives me more control over the arguments that go
> in, but I haven't been able to find it. Could you guide me regarding this
> or point me to a resource?

Apologies for the delay. It looks like you need to rebuild rootlesskit
with any option you want to add, here:

  https://github.com/rootless-containers/rootlesskit/blob/e83d7635183e1125798b2928b22002dfcc4a1168/pkg/network/pasta/pasta.go#L146

because there's currently no convenient command-line mechanism like the
one implemented by Podman, here:

  https://github.com/containers/common/blob/5a4ca2d5d35571556f6e7d1d5f024c19dc482135/libnetwork/pasta/pasta_linux.go#L174

I guess it would be nice to implement something similar, but I'm not
really familiar with rootlesskit otherwise. An alternative could be to
use a trivial wrapper at /usr/local/bin/pasta, a simple script doing:

--
#!/bin/sh

/usr/bin/pasta $@ --whatever-additional-option-here
--

-- 
Stefano

Re: Help with pasta usage

[David Gibson]

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On Mon, Nov 24, 2025 at 08:10:35PM -0330, Ayon T wrote:
> Hi, sorry it has been a while, I haven't been able to find the time to work
> on this problem.
> 
> However, I think I've managed to narrow down what the problem is, so I'm
> writing to you again!
> 
> I essentially ended up using a wrapper for pasta to try out a few different
> arguments with it, even though I went down a different route. I used
> "DOCKERD_ROOTLESS_ROOTLESSKIT_FLAGS" with `rootlesskit` to pass on a new
> location to a script wrapping the pasta binary.
> 
> I passed on the explicit local network IP of the DNS server that runs on my
> home network, and everything started working fine.
> 
> I'll explain: my server PC runs rootless containers – one of them runs a
> DNS server. On that PC itself, I redirect local DNS queries to 127.0.0.1
> (the first nameserver on /etc/resolv.conf). pasta picks up the first entry
> on /etc/resolv.conf and forwards DNS queries to it. But it seems like it
> cannot access localhost (probably by design?)

With its own default options, pasta will generally allow access from
loopback, but docker may (by design) add parameters that override that
behaviour.  Using 'ps' (or your wrapper) to find out the exact
arguments that docker is invoking pasta with would help.

> Once I add the local network IP (192.168.x.y) explicitly as the DNS server
> to forward queries to, things work, but I find this inefficient as it feels
> like queries shouldn't have to go through the local network for resolution,
> since the DNS server runs on that very device.

So, yes, it arguably should be possible to access the server via
127.0.0.1.  That said, I don't think there's any real inefficiency
here: the kernel will already direct traffic to a public-but-local
address over 'lo', so it won't actually hit the external network.

> Please advise me on what can be done about this and if I'm on the wrong
> track.
> 
> Regards,
> Ayon
> 
> On Tue, Jun 3, 2025 at 8:16 AM Stefano Brivio <sbrivio@redhat.com> wrote:
> 
> > On Fri, 23 May 2025 00:51:25 -0230
> > Ayon T <sanroz.mozan13@gmail.com> wrote:
> >
> > > I know you have been asking me to run pasta with arguments with docker,
> > but
> > > I'm not sure how to do this (pardon my inexperience). I use an
> > > override.conf file to set the default network and port driver of docker,
> > > and that's how I use pasta with docker. I have tried looking up how to do
> > > it in a different way that gives me more control over the arguments that
> > go
> > > in, but I haven't been able to find it. Could you guide me regarding this
> > > or point me to a resource?
> >
> > Apologies for the delay. It looks like you need to rebuild rootlesskit
> > with any option you want to add, here:
> >
> >
> > https://github.com/rootless-containers/rootlesskit/blob/e83d7635183e1125798b2928b22002dfcc4a1168/pkg/network/pasta/pasta.go#L146
> >
> > because there's currently no convenient command-line mechanism like the
> > one implemented by Podman, here:
> >
> >
> > https://github.com/containers/common/blob/5a4ca2d5d35571556f6e7d1d5f024c19dc482135/libnetwork/pasta/pasta_linux.go#L174
> >
> > I guess it would be nice to implement something similar, but I'm not
> > really familiar with rootlesskit otherwise. An alternative could be to
> > use a trivial wrapper at /usr/local/bin/pasta, a simple script doing:
> >
> > --
> > #!/bin/sh
> >
> > /usr/bin/pasta $@ --whatever-additional-option-here
> > --
> >
> > --
> > Stefano
> >
> >

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-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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