snap-store-proxy settings not being correctly applied

[Chris Johnston]

Charms using the snap layer are not properly applying snap-store-proxy configs from model-config. This appears to be caused by checking for the deprecated 'snap_proxy_url' which seems to have come from a couple of charms rather than 'snap_store_proxy_url' from the model-conifg. Repro:

$ juju add-model snap-test
$ juju model-config
...
snap-http-proxy default ""
snap-https-proxy default ""
snap-store-assertions controller |-
  type: store
  authority-id: canonical
  revision: 1
  store: fWH2JOYGcB0J5X0V5bmwvUc9lOswqn0m
  operator-id: 6KzCmN0esHnVQmCwxYPQg7rpJRht2CHn
  timestamp: 2020-05-05T14:57:12.150729Z
  url: http://<url>
  sign-key-sha3-384: ...

  ...
  ...
  ...
  ...
  ...
  ...
  ...
  ...
  ...
  ...
snap-store-proxy controller <id>
snap-store-proxy-url controller http://<url>
...

$ juju deploy cs:ubuntu
Located charm "cs:ubuntu-15".
Deploying charm "cs:ubuntu-15".

$ juju run --all -- sudo snap get core proxy -d
{
        "proxy": {
                "http": "",
                "https": "",
                "store": "<id>"
        }
}
$ juju deploy cs:canonical-livepatch
Located charm "cs:canonical-livepatch-35".
Deploying charm "cs:canonical-livepatch-35".
$ juju add-relation ubuntu canonical-livepatch
$ juju run --all -- sudo snap get core proxy -d
{
        "proxy": {
                "http": "",
                "https": "",
                "store": ""
        }
}
$ juju config canonical-livepatch snap_proxy_url="http://<url>"
$ juju run --all -- sudo snap get core proxy -d
{
        "proxy": {
                "http": "",
                "https": "",
                "store": "<id>"
        }
}

[Cory Johns (johnsca)]

This was re-reported at https://bugs.launchpad.net/layer-snap/+bug/1905009 with some more details.

[Stuart Bishop (stub)]

Can we just drop all the deprecated snap proxy code now? Or do we need a Juju version check, running the deprecated code only for old Juju deployments? Latter requires keeping the config.yaml noise.

[Stuart Bishop (stub)]

https://code.launchpad.net/~stub/layer-snap/+git/layer-snap-stub/+merge/394665

[George Kraft (cynerva)]

Cherry-pick to stable for Charmed Kubernetes:
https://github.com/charmed-kubernetes/layer-snap/commit/56e8a8c2a2ecd79556d26258e57627dda26ef907
https://github.com/charmed-kubernetes/layer-snap/commit/ca33fa62d05140a7940191876fa809810c3782d9