Re: Bug #909644: docker.io: dockerd warning: failed to retrieve docker-runc version: unknown output format: runc version spec: 1.0.1
Dear Go team,
So let met sum up this bug now to avoid you reading the backlog:
In short, docker doesn't recognize the output of `runc --version`, and
then it misbehaves and flood the log forever. To be more accurate,
docker is not happy because it wants to know the git commit that was
used to build runc. This information may or may not be part of the
output of `runc --version`: it depends on how runc was built. Actually,
there are two fields, `version` and `gitcommit`, that can be passed
optionally to runc during the build (as ldflags). Therefore the output
of `runc --version` varies accordingly.
So there's two ways out of that:
**Solution 1**
One is to patch docker, and fix their code so that it can handle various
runc version outputs. This is the way chosen by buildroot for example:
https://github.com/buildroot/buildroot/blob/master/package/docker-engine/0001-Fix-faulty-runc-version-commit-scrape.patch
Note that this patch is not the definitive solution: it just allows
docker to handle the output of runc *as built in buildroot*, and not in
every case. If we go this way, we'll do something similar, supporting
"debian's runc" output, and end up with a patch that has no chance to
make it upstream.
Maybe the core of the issue is that the `runc --version` output is
difficult to parse properly, and that's why docker upstream don't want
to bother fixing their code...
**Solution 2**
The other way is to modify the runc build so that we include the git
commit. I've pushed such a change on a branch at:
https://salsa.debian.org/go-team/packages/runc/commit/033a60b549b0935861c92bf4e5118d03ef443a8f
It's actually not that bad, no patch involved, it's really just adding
ldflags. The only downside I see is that there's an additional step when
a maintainer wants to release a new upstream version: he has to look for
the corresponding commit and add it to the file
`debian/upstream-version-gitcommits`. I provided a helper script to do
that, so it's really a small overhead.
**What do you think?**
I'm in favor of solution 2, it seems the path of least trouble, and is
also a correct thing to do IMHO. I'd like to have this fixed for buster,
as this issue has been opened for a long while.
If you agree with solution 2 I'll need some DD to upload a new version
of runc with this change (sorry to bother you...). Also this bug should
be re-assigned to runc if we solve it in the runc package.
For more details you can also look at upstream discussion:
https://github.com/moby/moby/issues/38709
All the best,
Arnaud
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