[receiver/kubeletstats] Support specifying context for kubeConfig auth_type (#26665) (#27240)

**Description:**
Support specifying context for `kubeConfig` `auth_type` when
communicating with a Kubernetes cluster.

**Link to tracking Issue:** 26665

**Testing:** unit test added

**Documentation:** kubeletstatsreceiver README updated

Signed-off-by: JACQUES Francois <[email protected]>

Author: hypnoce

.chloggen/kubelet_kubeconfig_context.yaml

@@ -0,0 +1,25 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: kubeletstatsreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Support specifying context for `kubeConfig` `auth_type`
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [26665]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

internal/k8sconfig/config.go

@@ -54,6 +54,9 @@ type APIConfig struct {
 	// token provided to the agent pod), or `kubeConfig` to use credentials
 	// from `~/.kube/config`.
 	AuthType AuthType `mapstructure:"auth_type"`
+
+	// When using auth_type `kubeConfig`, override the current context.
+	Context string `mapstructure:"context"`
 }
 
 // Validate validates the K8s API config
@@ -85,6 +88,9 @@ func CreateRestConfig(apiConf APIConfig) (*rest.Config, error) {
 	case AuthTypeKubeConfig:
 		loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
 		configOverrides := &clientcmd.ConfigOverrides{}
+		if apiConf.Context != "" {
+			configOverrides.CurrentContext = apiConf.Context
+		}
 		authConf, err = clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
 			loadingRules, configOverrides).ClientConfig()
 

internal/kubelet/client_test.go

@@ -154,37 +154,59 @@ func TestSAClientBadTLS(t *testing.T) {
 }
 
 func TestNewKubeConfigClient(t *testing.T) {
-	server := httptest.NewUnstartedServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		// Check if call is authenticated using provided kubeconfig
-		require.Equal(t, req.Header.Get("Authorization"), "Bearer my-token")
-		require.Equal(t, "/api/v1/nodes/nodename/proxy/", req.URL.EscapedPath())
-		// Send response to be tested
-		_, err := rw.Write([]byte(`OK`))
-		require.NoError(t, err)
-	}))
-	server.StartTLS()
-	defer server.Close()
-
-	kubeConfig, err := clientcmd.LoadFromFile("testdata/kubeconfig")
-	require.NoError(t, err)
-	kubeConfig.Clusters["my-cluster"].Server = "https://" + server.Listener.Addr().String()
-	tempKubeConfig := filepath.Join(t.TempDir(), "kubeconfig")
-	require.NoError(t, clientcmd.WriteToFile(*kubeConfig, tempKubeConfig))
-	t.Setenv("KUBECONFIG", tempKubeConfig)
-
-	p, err := NewClientProvider("nodename", &ClientConfig{
-		APIConfig: k8sconfig.APIConfig{
-			AuthType: k8sconfig.AuthTypeKubeConfig,
+	tests := []struct {
+		name    string
+		cluster string
+		context string
+	}{
+		{
+			name:    "current context",
+			cluster: "my-cluster-1",
+			context: "",
 		},
-		InsecureSkipVerify: true,
-	}, zap.NewNop())
-	require.NoError(t, err)
-	require.NotNil(t, p)
-	client, err := p.BuildClient()
-	require.NoError(t, err)
-	resp, err := client.Get("/")
-	require.NoError(t, err)
-	require.Equal(t, []byte(`OK`), resp)
+		{
+			name:    "override context",
+			cluster: "my-cluster-2",
+			context: "my-context-2",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			server := httptest.NewUnstartedServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+				// Check if call is authenticated using provided kubeconfig
+				require.Equal(t, req.Header.Get("Authorization"), "Bearer my-token")
+				require.Equal(t, "/api/v1/nodes/nodename/proxy/", req.URL.EscapedPath())
+				// Send response to be tested
+				_, err := rw.Write([]byte(`OK`))
+				require.NoError(t, err)
+			}))
+			server.StartTLS()
+			defer server.Close()
+
+			kubeConfig, err := clientcmd.LoadFromFile("testdata/kubeconfig")
+			require.NoError(t, err)
+			kubeConfig.Clusters[tt.cluster].Server = "https://" + server.Listener.Addr().String()
+			tempKubeConfig := filepath.Join(t.TempDir(), "kubeconfig")
+			require.NoError(t, clientcmd.WriteToFile(*kubeConfig, tempKubeConfig))
+			t.Setenv("KUBECONFIG", tempKubeConfig)
+
+			p, err := NewClientProvider("nodename", &ClientConfig{
+				APIConfig: k8sconfig.APIConfig{
+					AuthType: k8sconfig.AuthTypeKubeConfig,
+					Context:  tt.context,
+				},
+				InsecureSkipVerify: true,
+			}, zap.NewNop())
+			require.NoError(t, err)
+			require.NotNil(t, p)
+			client, err := p.BuildClient()
+			require.NoError(t, err)
+			resp, err := client.Get("/")
+			require.NoError(t, err)
+			require.Equal(t, []byte(`OK`), resp)
+		})
+	}
 }
 
 func TestBuildEndpoint(t *testing.T) {

internal/kubelet/testdata/kubeconfig

@@ -5,14 +5,24 @@ clusters:
 - cluster:
     certificate-authority-data: Y2VydA==
     server: https://my-cluster.address
-  name: my-cluster
+  name: my-cluster-1
+- cluster:
+    certificate-authority-data: Y2VydA==
+    server: https://my-cluster.address
+  name: my-cluster-2
 contexts:
 - context:
-    cluster: my-cluster
+    cluster: my-cluster-1
+    namespace: my-namespace
+    user: my-user
+  name: my-context-1
+- context:
+    cluster: my-cluster-2
     namespace: my-namespace
     user: my-user
-  name: my-context
-current-context: my-context
+  name: my-context-2
+
+current-context: my-context-1
 users:
 - name: my-user
   user:

receiver/kubeletstatsreceiver/README.md

@@ -132,6 +132,7 @@ receivers:
   kubeletstats:
     collection_interval: 20s
     auth_type: "kubeConfig"
+    context: "my-context"
     insecure_skip_verify: true
     endpoint: "${env:K8S_NODE_NAME}"
 exporters:
@@ -145,6 +146,7 @@ service:
 ```
 Note that using `auth_type` `kubeConfig`, the endpoint should only be the node name as the communication to the kubelet is proxied by the API server configured in the `kubeConfig`.
 `insecure_skip_verify` still applies by overriding the `kubeConfig` settings.
+If no `context` is specified, the current context or the default context is used.
 
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