juju 3.0 client cannot refresh --switch from cs to ch on 2.9 controller

[Heather Lanigan]

With a 2.9 juju client and controller

$ juju deploy cs:ubuntu csubuntu
Located charm "ubuntu" in charm-store, revision 21
Deploying "csubuntu" from charm-store charm "ubuntu", revision 21 in channel stable on xenial

If you then use a 3.0 juju client to refresh the charm:

$ juju refresh csubuntu --switch ch:ubuntu
ERROR series required for charm-hub charms (bad request)

17:08:29 TRACE juju.rpc.jsoncodec codec.go:227 -> {"request-id":6,"type":"Charms","version":5,"request":"ResolveCharms","params":{"resolve":[{"reference":"ch:ubuntu","charm-origin":{"source":"charm-hub","type":"","id":"","risk":"stable","architecture":"amd64","base":{"name":"ubuntu","channel":"16.04/stable"}},"switch-charm":true}]}}
17:08:29 TRACE juju.rpc.jsoncodec codec.go:121 <- {"request-id":6,"response":{"Results":[{"url":"ch:amd64/xenial/ubuntu-21","charm-origin":{"source":"charm-hub","type":"charm","id":"","risk":"stable","revision":21,"architecture":"amd64","base":{"name":"","channel":""},"series":"xenial","os":"ubuntu","channel":"16.04"},"supported-series":["xenial"]}]}}
17:08:29 INFO cmd refresher.go:336 Using channel "stable"
17:08:29 TRACE juju.rpc.jsoncodec codec.go:227 -> {"request-id":7,"type":"Charms","version":5,"request":"AddCharm","params":{"url":"ch:amd64/xenial/ubuntu-21","charm-origin":{"source":"charm-hub","type":"charm","id":"","risk":"stable","revision":21,"architecture":"amd64","base":{"name":"ubuntu","channel":"16.04/stable"}},"force":false}}
17:08:29 TRACE juju.rpc.jsoncodec codec.go:121 <- {"request-id":7,"error":"series required for charm-hub charms","error-code":"bad request","response":{}}

A 2.9 client succeeds:

$ juju refresh csubuntu --switch ch:ubuntu
Added charm-hub charm "ubuntu", revision 21 in channel stable, to the model

17:16:31 TRACE juju.rpc.jsoncodec codec.go:227 -> {"request-id":6,"type":"Charms","version":5,"request":"ResolveCharms","params":{"resolve":[{"reference":"ch:ubuntu","charm-origin":{"source":"charm-hub","type":"","id":"","risk":"stable","architecture":"amd64","base":{"name":"ubuntu","channel":"16.04/stable"},"series":"xenial","os":"ubuntu","channel":"16.04/stable"},"switch-charm":true}]}}
17:16:31 TRACE juju.rpc.jsoncodec codec.go:121 <- {"request-id":6,"response":{"Results":[{"url":"ch:amd64/xenial/ubuntu-21","charm-origin":{"source":"charm-hub","type":"charm","id":"","risk":"stable","revision":21,"architecture":"amd64","base":{"name":"","channel":""},"series":"xenial","os":"ubuntu","channel":"16.04"},"supported-series":["xenial"]}]}}
17:16:31 INFO cmd refresher.go:338 Using channel "stable"
17:16:31 TRACE juju.rpc.jsoncodec codec.go:227 -> {"request-id":7,"type":"Charms","version":5,"request":"AddCharm","params":{"url":"ch:amd64/xenial/ubuntu-21","charm-origin":{"source":"charm-hub","type":"charm","id":"","risk":"stable","revision":21,"architecture":"amd64","base":{"name":"ubuntu","channel":"16.04/stable"},"series":"xenial","os":"ubuntu","channel":"16.04/stable"},"force":false,"series":"xenial"}}
17:16:33 TRACE juju.rpc.jsoncodec codec.go:121 <- {"request-id":7,"response":{"charm-origin":{"source":"charm-hub","type":"charm","id":"DksXQKAQTZfsUmBAGanZAhpoS4dpmXel","hash":"7272c626e5ef67136c857230d76dc70ee27da626835a2467d91b9860aaac6865","risk":"stable","revision":21,"architecture":"amd64","base":{"name":"","channel":""},"series":"xenial","os":"ubuntu","channel":"16.04"}}}
17:16:33 INFO cmd refresh.go:441 Added charm-hub charm "ubuntu", revision 21 in channel stable, to the model

[Heather Lanigan (hmlanigan)]

The 2.9 client includes series in the AddCharm params, while the 3.0 client does not.

At the very least, the 3.0 client error message is extremely misleading.

[Heather Lanigan (hmlanigan)]

This impacts terraform's ability to use the 3.3 code base while trying to support 2.9.45 and 3.x. The issue is in the params argument struct

[Ian Booth (wallyworld)]

The next 2.9.46 candidate release will not include a fix for this bug and we don't plan on any more 2.9 releases. As such it is being removed from its 2.9 milestone.

If the bug is still important to you, let us know and we can consider it for inclusion on a 3.x milestone.