Juju cannot deploy charm revision from closed track: unable to fetch OCI image resources

[Alex Lutay]

Hi,

It is a bugreport branched from the MM question:
> https://chat.charmhub.io/charmhub/pl/3huptnewqjyg3ghgcnx5eydgjh

---
The charmhub track can be closed, but the last revision there is still installable,
e.g. mysql-k8s or mysql-router-k8s in the latest/edge.
It looks like resources are no longer reachable for the closed tracks/revisions:

ubuntu@taurus-dev:~$ juju deploy mysql-router-k8s --channel latest/edge --trust
Located charm "mysql-router-k8s" in charm-hub, revision 24
Deploying "mysql-router-k8s" from charm-hub charm "mysql-router-k8s", revision 24 in channel latest/edge on jammy

ubuntu@taurus-dev:~$ juju debug-log --tail
...
controller-0: 13:24:27 ERROR juju.worker.caasapplicationprovisioner.runner exited "mysql-router-k8s": getting OCI image resources: unable to fetch OCI image resources for mysql-router-k8s: while getting resource from charmhub: resource "mysql-router-image" not found
---

Sergio reply: "... it seems strange that you can install anything from a channel that is closed ..."

The discussion on Engineering meeting went to no final decision, bugreported here:

Juju either have to:
1) do NOT allow to install revisions from closed tracks (e.g. snap way of closing tracks)
2) allow to install revision from closed tracks => fix resources availability (e.g. OCI for K8s charms).

Thank you!

---

P.S Keep in mind, it is NOT possible to install charm by revision too (using closed channel), but possible for the same revision using open channel:

```
juju deploy mysql-router-k8s --revision 24 --trust --channel latest/edge # fail
juju deploy mysql-router-k8s --revision 24 --trust --channel 8.0/edge # works
```

Which means: resources are still available in sore, but juju do not see them if channel is closed.

P.P.S see also charmcraft discussion here: https://github.com/canonical/charmcraft/issues/1108

[Alex Lutay (taurus)]

The similar discussion in snapstore: https://bugs.launchpad.net/snapstore-server/+bug/2020681

[Joseph Phillips (manadart)]

I think we should disallow *new* deployments from closed tracks.

But we don't want to strand someone who has such a revision deployed, with regard to scaling concerns.

[Sergio Schvezov (sergiusens)]

I just want to pedantic-clarify, that this rule should apply to closed channels; the track piece is a component to said channel.

[John A Meinel (jameinel)]

just like you can deploy a charm by revision, you can also deploy resources by revision. (IIRC, juju deploy mysql-router-k8s --revision 24 --resource mysql-router-image=10
note that I don't know what revisions of the mysql-router-image are available)

There are existing issues against charmhub that it doesn't match a given charm revision with its resources (if you try to deploy revision 20 of the charm but target the channel 8.0/edge it will grab the latest resources from 8.0/edge and not the resources that 'came with' the charm when it was at revision 20).

AFAIK, there is no way to disable a revision that has been exposed publicly in the past. (if you pushed a revision 10 to the store, but never published it, then it won't be accessible, but if you have published 10, then someone can always ask for --revision 10 in the future.)

That would be more on the Store, than on Juju if we wanted to provide that sort of close-and-fully-remove.

As for Joe's comment, according to Alex we already do that:
```
 juju deploy mysql-router-k8s --revision 24 --trust --channel latest/edge # fail
```

The issue is that we support any revision that the store exposes, but the store doesn't align the resources with the revision. Either way I'm pretty sure this is still a snapstore server bug, not a bug in juju.

[John A Meinel (jameinel)]

It seems to be failing for the wrong reason, but it is refusing to deploy from a non-existent channel:
```
$ juju deploy mysql-router --channel nosuchchannel/stable --revision 24
ERROR listing resources for charm "ch:amd64/mysql-router-24": No revision was found in the Store.
ERROR failed to deploy charm "mysql-router"
```

And for a channel that exists but doesn't have any revisions:
```
$ juju deploy mysql-router --channel latest/stable --revision 24
ERROR listing resources for charm "ch:amd64/mysql-router-24": No revision was found in the Store.
ERROR failed to deploy charm "mysql-router"
```

And mysql-router itself doesn't even have resources (that I can find).

[Alex Lutay (taurus)]

Hi Jon, thank you for trying to trace this down.

TL;DR: is it not possible to deploy closed channels using Juju 3.1.6 today. Resolved?

re: > And mysql-router itself doesn't even have resources (that I can find)

The ticket is about K8s charms: "unable to fetch OCI image resources", but you were checking mysql-router VM.

Anyway, today, using Juju 3.1.6 I cannot reproduce the initial issue at all
(e.g. mysql-k8s latest/* are closed):

> > juju deploy mysql-k8s --channel latest/edge --trust
> ERROR selecting releases: charm or bundle not found for channel "latest/edge", platform "amd64"
> available releases are:
> channel "8.0/edge": available series are: jammy
> channel "8.0/stable": available series are: jammy
> channel "8.0/candidate": available series are: jammy
> channel "8.0/beta": available series are: jammy

I believe something has changed on Juju/Charmhub level.