Merge pull request juju#17412 from nvinuesa/juju-6048

juju#17412

In the context of dropping the fan networking support on 4.0+, this patch removes the fanconfigurer worker, which applied the fan configuration using `fanctl`, which is part of the ubuntu-fan package and no longer installed after the patch juju#17410 lands.

All api endpoints regarding fanconfigurer have also been removed.

## Checklist


- [X] Code style: imports ordered, good names, simple structure, etc
- [X] Comments saying why design decisions were made
- [X] Go unit tests, with comments saying what you're testing
- [ ] ~[Integration tests](https://github.com/juju/juju/tree/main/tests), with comments saying what you're testing~
- [ ] ~[doc.go](https://discourse.charmhub.io/t/readme-in-packages/451) added or updated in changed packages~

## QA steps

Bootstrap on aws and deploy:

```
juju bootstrap aws c
juju add-model m
juju deploy ubuntu --to lxd
```
and make sure there are no errors on the logs.

Also, 3.6->4.0 migration should not be broken:
```
juju_36 bootstrap aws 36
juju_36 add-model m
juju_36 deploy ubuntu --to lxd
# install this patch at this point
juju bootstrap aws c40
juju switch c36:admin/m
juju migrate c40
```
Check the logs and the status after migration, the model should have been correctly migrated.
## Links

**Jira card:** JUJU-6048

api/agent/fanconfigurer/facade.go

@@ -25,6 +25,8 @@ type Facade struct {
 	caller base.FacadeCaller
 }
 
+// TODO(nvinuesa): This entire facade should be removed since it's not used
+// anymore (the fanconfigurer worker has been removed).
 // NewFacade creates a new client-side FanConfigu	er facade.
 func NewFacade(caller base.APICaller, options ...Option) *Facade {
 	return &Facade{

apiserver/facades/agent/fanconfigurer/register.go

@@ -10,6 +10,8 @@ import (
 	"github.com/juju/juju/apiserver/facade"
 )
 
+// TODO(nvinuesa): This entire facade should be removed since it's not used
+// anymore (the fanconfigurer worker has been removed).
 // Register is called to expose a package of facades onto a given registry.
 func Register(registry facade.FacadeRegistry) {
 	registry.MustRegister("FanConfigurer", 1, func(stdCtx context.Context, ctx facade.ModelContext) (facade.Facade, error) {

cmd/jujud-controller/agent/engine_test.go

@@ -119,7 +119,6 @@ var (
 		"api-address-updater",
 		"deployer",
 		"disk-manager",
-		"fan-configurer",
 		"is-bootstrap-flag",
 		"is-bootstrap-gate",
 		"is-controller-flag",

cmd/jujud-controller/agent/machine/manifolds.go

@@ -69,7 +69,6 @@ import (
 	"github.com/juju/juju/internal/worker/deployer"
 	"github.com/juju/juju/internal/worker/diskmanager"
 	"github.com/juju/juju/internal/worker/externalcontrollerupdater"
-	"github.com/juju/juju/internal/worker/fanconfigurer"
 	"github.com/juju/juju/internal/worker/filenotifywatcher"
 	"github.com/juju/juju/internal/worker/fortress"
 	"github.com/juju/juju/internal/worker/gate"
@@ -942,11 +941,6 @@ func IAASManifolds(config ManifoldsConfig) dependency.Manifolds {
 			NewWorker:     hostkeyreporter.NewWorker,
 		})),
 
-		fanConfigurerName: ifNotMigrating(fanconfigurer.Manifold(fanconfigurer.ManifoldConfig{
-			APICallerName: apiCallerName,
-			Clock:         config.Clock,
-		})),
-
 		certificateUpdaterName: ifFullyUpgraded(certupdater.Manifold(certupdater.ManifoldConfig{
 			AgentName:                agentName,
 			AuthorityName:            certificateWatcherName,
@@ -959,12 +953,10 @@ func IAASManifolds(config ManifoldsConfig) dependency.Manifolds {
 
 		// The machiner Worker will wait for the identified machine to become
 		// Dying and make it Dead; or until the machine becomes Dead by other
-		// means. This worker needs to be launched after fanconfigurer
-		// so that it reports interfaces created by it.
+		// means.
 		machinerName: ifNotMigrating(machiner.Manifold(machiner.ManifoldConfig{
-			AgentName:         agentName,
-			APICallerName:     apiCallerName,
-			FanConfigurerName: fanConfigurerName,
+			AgentName:     agentName,
+			APICallerName: apiCallerName,
 		})),
 
 		// DBAccessor is a manifold that provides a DBAccessor worker
@@ -1333,7 +1325,6 @@ const (
 	toolsVersionCheckerName       = "tools-version-checker"
 	machineActionName             = "machine-action-runner"
 	hostKeyReporterName           = "host-key-reporter"
-	fanConfigurerName             = "fan-configurer"
 	externalControllerUpdaterName = "external-controller-updater"
 	isPrimaryControllerFlagName   = "is-primary-controller-flag"
 	isControllerFlagName          = "is-controller-flag"

cmd/jujud-controller/agent/machine/manifolds_test.go

@@ -87,7 +87,6 @@ func (s *ManifoldsSuite) TestManifoldNamesIAAS(c *gc.C) {
 			"deployer",
 			"disk-manager",
 			"external-controller-updater",
-			"fan-configurer",
 			"file-notify-watcher",
 			"host-key-reporter",
 			"http-server-args",
@@ -731,18 +730,6 @@ var expectedMachineManifoldsWithDependenciesIAAS = map[string][]string{
 		"upgrade-steps-gate",
 	},
 
-	"fan-configurer": {
-		"agent",
-		"api-caller",
-		"api-config-watcher",
-		"migration-fortress",
-		"migration-inactive-flag",
-		"upgrade-check-flag",
-		"upgrade-check-gate",
-		"upgrade-steps-flag",
-		"upgrade-steps-gate",
-	},
-
 	"file-notify-watcher": {
 		"agent",
 		"is-controller-flag",
@@ -964,7 +951,6 @@ var expectedMachineManifoldsWithDependenciesIAAS = map[string][]string{
 		"agent",
 		"api-caller",
 		"api-config-watcher",
-		"fan-configurer",
 		"migration-fortress",
 		"migration-inactive-flag",
 		"upgrade-check-flag",

cmd/jujud/agent/engine_test.go

@@ -45,7 +45,6 @@ var (
 		"api-address-updater",
 		"deployer",
 		"disk-manager",
-		"fan-configurer",
 		"is-bootstrap-flag",
 		"is-bootstrap-gate",
 		"is-controller-flag",

cmd/jujud/agent/machine/manifolds.go

@@ -47,7 +47,6 @@ import (
 	"github.com/juju/juju/internal/worker/credentialvalidator"
 	"github.com/juju/juju/internal/worker/deployer"
 	"github.com/juju/juju/internal/worker/diskmanager"
-	"github.com/juju/juju/internal/worker/fanconfigurer"
 	"github.com/juju/juju/internal/worker/fortress"
 	"github.com/juju/juju/internal/worker/gate"
 	"github.com/juju/juju/internal/worker/hostkeyreporter"
@@ -414,19 +413,12 @@ func IAASManifolds(config ManifoldsConfig) dependency.Manifolds {
 			NewWorker:     hostkeyreporter.NewWorker,
 		})),
 
-		fanConfigurerName: ifNotMigrating(fanconfigurer.Manifold(fanconfigurer.ManifoldConfig{
-			APICallerName: apiCallerName,
-			Clock:         config.Clock,
-		})),
-
 		// The machiner Worker will wait for the identified machine to become
 		// Dying and make it Dead; or until the machine becomes Dead by other
-		// means. This worker needs to be launched after fanconfigurer
-		// so that it reports interfaces created by it.
+		// means.
 		machinerName: ifNotMigrating(machiner.Manifold(machiner.ManifoldConfig{
-			AgentName:         agentName,
-			APICallerName:     apiCallerName,
-			FanConfigurerName: fanConfigurerName,
+			AgentName:     agentName,
+			APICallerName: apiCallerName,
 		})),
 
 		// The diskmanager worker periodically lists block devices on the
@@ -679,7 +671,6 @@ const (
 	toolsVersionCheckerName  = "tools-version-checker"
 	machineActionName        = "machine-action-runner"
 	hostKeyReporterName      = "host-key-reporter"
-	fanConfigurerName        = "fan-configurer"
 	instanceMutaterName      = "instance-mutater"
 	auditConfigUpdaterName   = "audit-config-updater"
 	stateConverterName       = "state-converter"

cmd/jujud/agent/machine/manifolds_test.go

@@ -73,7 +73,6 @@ func (s *ManifoldsSuite) TestManifoldNamesIAAS(c *gc.C) {
 			"clock",
 			"deployer",
 			"disk-manager",
-			"fan-configurer",
 			"host-key-reporter",
 			"instance-mutater",
 			"log-sender",
@@ -460,18 +459,6 @@ var expectedMachineManifoldsWithDependenciesIAAS = map[string][]string{
 		"upgrade-steps-gate",
 	},
 
-	"fan-configurer": {
-		"agent",
-		"api-caller",
-		"api-config-watcher",
-		"migration-fortress",
-		"migration-inactive-flag",
-		"upgrade-check-flag",
-		"upgrade-check-gate",
-		"upgrade-steps-flag",
-		"upgrade-steps-gate",
-	},
-
 	"host-key-reporter": {
 		"agent",
 		"api-caller",
@@ -565,7 +552,6 @@ var expectedMachineManifoldsWithDependenciesIAAS = map[string][]string{
 		"agent",
 		"api-caller",
 		"api-config-watcher",
-		"fan-configurer",
 		"migration-fortress",
 		"migration-inactive-flag",
 		"upgrade-check-flag",