`dockerd` service not starting

[Tanguy LE CARROUR]

Hi Guix,

My `dockerd` service has stopped working weeks (months!?) ago, but I've
had no use for it in the meantime, so it was no big deal, until today…

My configuration looks like this:

```scm
;…
(use-service-modules desktop docker)

(operating-system
  ;…
  (services
    (append
      (list
        (service docker-service-type)
       ;…
       ))))
```

This used to be enough. But now, it doesn't auto-start any more and,
when I `sudo herd start dockerd`, it hangs and displays:

```console
$ sudo herd start dockerd
Password:
Service dockerd could not be started.
herd: failed to start service dockerd
```

The log contains the following:

```log:/var/log/docker.log
time="2022-03-31T11:31:32.027833616+02:00" level=info msg="Starting up"
time="2022-03-31T11:31:32.031576010+02:00" level=info msg="parsed scheme: 
\"unix\"" module=grpc
time="2022-03-31T11:31:32.031661605+02:00" level=info msg="scheme \"unix\" not 
registered, fallback to default scheme" module=grpc
time="2022-03-31T11:31:32.031760157+02:00" level=info msg="ccResolverWrapper: 
sending update to cc: {[{unix:///run/containerd/containerd.sock 0  <nil>}] 
<nil>}" module=grpc
time="2022-03-31T11:31:32.031816856+02:00" level=info msg="ClientConn switching 
balancer to \"pick_first\"" module=grpc
failed to start daemon: failed to dial "/run/containerd/containerd.sock": 
unknown service containerd.services.namespaces.v1.Namespaces: not implemented
```

`containerd` seems to be running fine, even though I sometimes see the
following in the log:

```log:/var/log/docker.log
failed to start containerd: exec: "containerd": executable file not found in 
$PATH
```

Actually, it looks like a problem reported in another thread [1][] a year ago,
that hasn't (yet) found a solution!? :-(

[1]: https://lists.gnu.org/archive/html/help-guix/2021-06/msg00019.html

Any help welcome!

Regards,

-- 
Tanguy