Thank you for the help, @wallyworld. I originally documented some of the steps I took in this thread, but the gist is that I had issues and a missing apiaddress in my agent.conf. I also seem to be missing the apipassword entry. I just set it to the same as the statepassword and it seems the controller is up, but none of the units are connected.
Looking at a random unit, I see logs with
2020-08-01 00:16:39 INFO juju.cmd supercommand.go:91 running jujud [2.8.0 0 d816abe62fbf6787974e5c4e140818ca08586e44 gc go1.14.4]
2020-08-01 00:16:39 DEBUG juju.cmd supercommand.go:92 args: []string{"/var/lib/juju/tools/machine-17/jujud", "machine", "--data-dir", "/var/lib/juju", "--machine-id", "17", "--debug"}
2020-08-01 00:16:39 DEBUG juju.utils gomaxprocs.go:24 setting GOMAXPROCS to 24
2020-08-01 00:16:39 DEBUG juju.agent agent.go:575 read agent config, format "2.0"
2020-08-01 00:16:39 INFO juju.cmd.jujud agent.go:138 setting logging config to "<root>=WARNING;unit=DEBUG"
2020-08-01 00:16:39 ERROR juju.worker.apiconfigwatcher manifold.go:132 retrieving API addresses: No apidetails in config
2020-08-01 00:16:39 ERROR juju.worker.apiconfigwatcher manifold.go:132 retrieving API addresses: No apidetails in config
2020-08-01 00:16:39 ERROR juju.worker.apiconfigwatcher manifold.go:132 retrieving API addresses: No apidetails in config
2020-08-19 04:13:41 ERROR juju.worker.dependency engine.go:671 "api-caller" manifold worker returned unexpected error: [6bad3a] "machine-17" cannot open api: API info not available
Sure enough, this agent.conf has no apiserver or apipassword. I added those, but that doesn’t seem to have done the trick.
2020-08-19 04:44:03 INFO juju.cmd supercommand.go:91 running jujud [2.8.0 0 d816abe62fbf6787974e5c4e140818ca08586e44 gc go1.14.4]
2020-08-19 04:44:03 DEBUG juju.cmd supercommand.go:92 args: []string{"/var/lib/juju/tools/machine-17/jujud", "machine", "--data-dir", "/var/lib/juju", "--machine-id", "17", "--debug"}
2020-08-19 04:44:03 DEBUG juju.utils gomaxprocs.go:24 setting GOMAXPROCS to 24
2020-08-19 04:44:03 DEBUG juju.agent agent.go:575 read agent config, format "2.0"
2020-08-19 04:44:03 INFO juju.cmd.jujud agent.go:138 setting logging config to "<root>=WARNING;unit=DEBUG"
2020-08-19 04:44:03 ERROR juju.worker.apicaller connect.go:204 Failed to connect to controller: invalid entity name or password (unauthorized access)
So at this point I’m able to juju status again! progress!