Virtualised microk8s registry settings not correctly inferred.

Expected Behavior

Tilt correctly infers both the Host and hostFromCluster values of a registry when using microk8s in a vm. The Host should probably be the address of the registry, as addressable from the host machine (i.e. the IP address of the VM) and hostFromCluster should be localhost.

Current Behavior

The Host value is hard-coded to be localhost: https://github.com/tilt-dev/tilt/blob/77ae37f8f66c4b2d6df5eb526bd71954be73ecf2/internal/k8s/registry.go#L101

Context

tilt doctor Output

$ tilt doctor
Tilt: v0.23.9, built 2022-01-27
System: darwin-arm64
---
Docker
- Host: [default]
- Server Version: 20.10.12
- API Version: 1.41
- Builder: 2
- Compose Version: v2.2.3
---
Kubernetes
- Env: microk8s
- Context: microk8s
- Cluster Name: microk8s-cluster
- Namespace: default
- Container Runtime: containerd
- Version: v1.22.5-3+2cf820a97417ce
- Cluster Local Registry: {Host:localhost:32000 hostFromCluster: SingleName:}
---

About Your Use Case

I use macos. Docker is running in a VM using Docker Desktop. microk8s is running in a different one using multipass. I have enabled microk8s local registry. In the Docker VM, localhost (the inferred registry host) is referring to the docker vm, not the host vm. default_registry (as discussed in #4125) can not be used to override the inferred registry values.

When I hack DecideRegistry to always use the default_registry value, things work, so I think my issue is only related to the inference of the registry settings for microk8s.

Start in internal/k8s/registry.go at DecideRegistry and the linked hard-coded Host line. Use the reported tilt doctor output and virtualized microk8s setup as the reproduction target; done means Host is reachable from the host machine while hostFromCluster is localhost.