In place upgrades fail in 4.0-beta4

[Simon Richardson]

In place upgrades fail in 4.0-beta4.

The repo steps can be followed:

$ export JUJU_BUILD_NUMBER=0
$ export DOCKER_USERNAME=docker.io/<your-docker-username>
$ make seed-repository
$ make install simplestreams push-release-operator-image
# start an http server in `_build/simplestreams/tools` with `python3 -m http.server`
$ juju bootstrap microk8s --config agent-metadata-url=<ip-for-simplestreams> --config caas-image-repo=docker.io/<your-docker-username>
$ juju status -m controller
Model Controller Cloud/Region Version Timestamp
controller microk8s microk8s 4.0-beta4 16:02:52+1:00
# increment version/version.go to 4.0-beta5
$ make install simplestreams push-release-operator-image
$ juju upgrade-controller
best version:
    4.0-beta5
started upgrade to 4.0-beta5
$ juju status
Model Controller Cloud/Region Version Timestamp
controller microk8s microk8s 4.0-beta5 16:14:11+1:00
$ kubectl -ncontroller-microk8s-localhost describe deployment modeloperator | grep jujud-operator:
    Image

This will fail to upgrade because:

 - upgrade-database-runner can't run because it needs service-factory
 - service-factory can't run because it needs provider-tracker
 - provider-tracker can't run because it needs upgrade-database-flag
 - upgrade-database-flag isn't set because upgrade-database-gate is not unlocked (by the upgrade-database-runner)

[Simon Richardson (simonrichardson)]

PR: https://github.com/juju/juju/pull/17549