Merge pull request #51312 from andrewsykim/50986

Automatic merge from submit-queue (batch tested with PRs 50932, 49610, 51312, 51415, 50705)

Deprecation warnings for auto detecting cloud providers

**What this PR does / why we need it**:
Adds deprecation warnings for auto detecting cloud providers. As part of the initiative for out-of-tree cloud providers, this feature is conflicting since we're shifting the dependency of kubernetes core into cAdvisor. In the future kubelets should be using `--cloud-provider=external` or no cloud provider at all. 

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #50986

**Special notes for your reviewer**:
NOTE: I still have to coordinate with sig-node and kubernetes-dev to get approval for this deprecation, I'm only opening this PR since we're close to code freeze and it's something presentable.  

**Release note**:
```release-note
Deprecate auto detecting cloud providers in kubelet. Auto detecting cloud providers go against the initiative for out-of-tree cloud providers as we'll now depend on cAdvisor integrations with cloud providers instead of the core repo. In the near future, `--cloud-provider` for kubelet will either be an empty string or `external`. 
```

cmd/kubelet/app/options/options.go

@@ -121,8 +121,12 @@ func NewKubeletFlags() *KubeletFlags {
 		KubeConfig:              flag.NewStringFlag("/var/lib/kubelet/kubeconfig"),
 		ContainerRuntimeOptions: *NewContainerRuntimeOptions(),
 		CertDirectory:           "/var/run/kubernetes",
-		CloudProvider:           v1alpha1.AutoDetectCloudProvider,
 		RootDirectory:           v1alpha1.DefaultRootDir,
+		// DEPRECATED: auto detecting cloud providers goes against the initiative
+		// for out-of-tree cloud providers as we'll now depend on cAdvisor integrations
+		// with cloud providers instead of in the core repo.
+		// More details here: https://github.com/kubernetes/kubernetes/issues/50986
+		CloudProvider: v1alpha1.AutoDetectCloudProvider,
 	}
 }
 
@@ -220,7 +224,7 @@ func (f *KubeletFlags) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&f.CertDirectory, "cert-dir", f.CertDirectory, "The directory where the TLS certs are located. "+
 		"If --tls-cert-file and --tls-private-key-file are provided, this flag will be ignored.")
 
-	fs.StringVar(&f.CloudProvider, "cloud-provider", f.CloudProvider, "The provider for cloud services. By default, kubelet will attempt to auto-detect the cloud provider. Specify empty string for running with no cloud provider.")
+	fs.StringVar(&f.CloudProvider, "cloud-provider", f.CloudProvider, "The provider for cloud services. By default, kubelet will attempt to auto-detect the cloud provider (deprecated). Specify empty string for running with no cloud provider, this will be the default in upcoming releases.")
 	fs.StringVar(&f.CloudConfigFile, "cloud-config", f.CloudConfigFile, "The path to the cloud provider configuration file.  Empty string for no configuration file.")
 
 	fs.StringVar(&f.RootDirectory, "root-dir", f.RootDirectory, "Directory path for managing kubelet files (volume mounts,etc).")

cmd/kubelet/app/server.go

@@ -283,6 +283,10 @@ func run(s *options.KubeletServer, kubeDeps *kubelet.Dependencies) (err error) {
 		}
 	}
 
+	if s.CloudProvider == kubeletconfigv1alpha1.AutoDetectCloudProvider {
+		glog.Warning("--cloud-provider=auto-detect is deprecated. The desired cloud provider should be set explicitly")
+	}
+
 	if kubeDeps.Cloud == nil {
 		if !cloudprovider.IsExternal(s.CloudProvider) && s.CloudProvider != kubeletconfigv1alpha1.AutoDetectCloudProvider {
 			cloud, err := cloudprovider.InitCloudProvider(s.CloudProvider, s.CloudConfigFile)

pkg/kubelet/apis/kubeletconfig/v1alpha1/defaults.go

@@ -32,6 +32,10 @@ import (
 const (
 	DefaultRootDir = "/var/lib/kubelet"
 
+	// DEPRECATED: auto detecting cloud providers goes against the initiative
+	// for out-of-tree cloud providers as we'll now depend on cAdvisor integrations
+	// with cloud providers instead of in the core repo.
+	// More details here: https://github.com/kubernetes/kubernetes/issues/50986
 	AutoDetectCloudProvider = "auto-detect"
 
 	defaultIPTablesMasqueradeBit = 14

pkg/kubelet/kubelet.go

@@ -965,7 +965,11 @@ type Kubelet struct {
 	volumeManager volumemanager.VolumeManager
 
 	// Cloud provider interface.
-	cloud                   cloudprovider.Interface
+	cloud cloudprovider.Interface
+	// DEPRECATED: auto detecting cloud providers goes against the initiative
+	// for out-of-tree cloud providers as we'll now depend on cAdvisor integrations
+	// with cloud providers instead of in the core repo.
+	// More details here: https://github.com/kubernetes/kubernetes/issues/50986
 	autoDetectCloudProvider bool
 	// Indicates that the node initialization happens in an external cloud controller
 	externalCloudProvider bool