feat: Add support for in-cluster auth

Closes #223

pkg/collector/cluster_test.go

@@ -1,9 +1,9 @@
 package collector
 
 import (
-	"encoding/json"
 	"io/ioutil"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -16,14 +16,13 @@ import (
 
 func TestNewClusterCollectorBadPath(t *testing.T) {
 	testOpts := ClusterOpts{Kubeconfig: "bad path"}
-	result, funcErr := NewClusterCollector(&testOpts, []string{})
+	_, err := NewClusterCollector(&testOpts, []string{})
 
-	if funcErr.Error() != "invalid configuration: no configuration has been provided" {
-		out, err := json.Marshal(result)
+	if !strings.Contains(err.Error(), "no configuration has been provided") {
 		if err != nil {
-			t.Errorf("Should have errored with invalid configuration error instead got: %s", string(out))
+			t.Errorf("Should have errored with invalid configuration error instead got: %s", err)
 		} else {
-			t.Errorf("Should have errored instead got: %s", funcErr)
+			t.Errorf("Should have failed but succeeded")
 		}
 	}
 }

pkg/collector/kube.go

@@ -21,30 +21,48 @@ func newKubeCollector(kubeconfig string, kubecontext string, discoveryClient dis
 	if discoveryClient != nil {
 		col.discoveryClient = discoveryClient
 	} else {
-		pathOptions := clientcmd.NewDefaultPathOptions()
-		if kubeconfig != "" {
-			pathOptions.GlobalFile = kubeconfig
+		var err error
+		if col.restConfig, err = newClientRestConfig(kubeconfig, kubecontext, rest.InClusterConfig); err != nil {
+			return nil, fmt.Errorf("failed to assemble client config: %w", err)
 		}
 
-		config, err := pathOptions.GetStartingConfig()
-
-		configOverrides := clientcmd.ConfigOverrides{}
-		if kubecontext != "" {
-			configOverrides.CurrentContext = kubecontext
+		if discoveryClient, err = discovery.NewDiscoveryClientForConfig(col.restConfig); err != nil {
+			return nil, fmt.Errorf("failed to create client: %w", err)
 		}
+	}
 
-		clientConfig := clientcmd.NewDefaultClientConfig(*config, &configOverrides)
-		col.restConfig, err = clientConfig.ClientConfig()
-		if err != nil {
-			return nil, err
-		}
+	return col, nil
+}
 
-		if col.discoveryClient, err = discovery.NewDiscoveryClientForConfig(col.restConfig); err != nil {
-			return nil, err
+func newClientRestConfig(kubeconfig string, kubecontext string, inClusterFn func() (*rest.Config, error)) (*rest.Config, error) {
+	if kubeconfig == "" {
+		if restConfig, err := inClusterFn(); err == nil {
+			return restConfig, nil
 		}
 	}
 
-	return col, nil
+	pathOptions := clientcmd.NewDefaultPathOptions()
+	if kubeconfig != "" {
+		pathOptions.GlobalFile = kubeconfig
+	}
+
+	config, err := pathOptions.GetStartingConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	configOverrides := clientcmd.ConfigOverrides{}
+	if kubecontext != "" {
+		configOverrides.CurrentContext = kubecontext
+	}
+
+	clientConfig := clientcmd.NewDefaultClientConfig(*config, &configOverrides)
+	restConfig, err := clientConfig.ClientConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	return restConfig, nil
 }
 
 func (c *kubeCollector) GetServerVersion() (*judge.Version, error) {

pkg/collector/kube_test.go

@@ -1,6 +1,7 @@
 package collector
 
 import (
+	"k8s.io/client-go/rest"
 	"os"
 	"path/filepath"
 	"testing"
@@ -33,36 +34,6 @@ func TestNewKubeCollectorError(t *testing.T) {
 	}
 }
 
-func TestNewKubeCollectorWithKubeconfigPath(t *testing.T) {
-	_, err := newKubeCollector("../../fixtures/kube.config.basic", "", nil)
-	if err != nil {
-		t.Fatalf("Failed with: %s", err)
-	}
-}
-
-func TestNewKubeCollectorMultipleFiles(t *testing.T) {
-	kcEnvVar := "KUBECONFIG"
-	oldKubeConfig, oldSet := os.LookupEnv(kcEnvVar)
-
-	if err := os.Setenv(kcEnvVar, "../../fixtures/kube.config.empty:../../fixtures/kube.config.basic"); err != nil {
-		t.Fatalf("Failed so set %s env variable for test: %s", kcEnvVar, err)
-	}
-
-	if _, err := newKubeCollector("", "", nil); err != nil {
-		t.Fatalf("Failed with: %s", err)
-	}
-
-	var err error
-	if oldSet {
-		err = os.Setenv(kcEnvVar, oldKubeConfig)
-	} else {
-		err = os.Unsetenv(kcEnvVar)
-	}
-	if err != nil {
-		t.Fatalf("Failed so reset %s env variable after test: %s", kcEnvVar, err)
-	}
-}
-
 func TestGetServerVersion(t *testing.T) {
 	gitVersion := "v1.2.3"
 	expectedVersion, _ := goversion.NewVersion(gitVersion)
@@ -105,12 +76,83 @@ func TestContext(t *testing.T) {
 func TestContextMissing(t *testing.T) {
 	expectedContext := "non-existent"
 
-	_, err := newKubeCollector("../../fixtures/kube.config.context", expectedContext, nil)
+	_, err := newKubeCollector(filepath.Join(FIXTURES_DIR, "kube.config.context"), expectedContext, nil)
 	if err == nil {
 		t.Fatalf("Expected to fail when uisng non-existent context: %s", expectedContext)
 	}
 }
 
+func TestNewClientRestConfig(t *testing.T) {
+	_, err := newClientRestConfig("", "", rest.InClusterConfig)
+	if err != nil {
+		t.Fatalf("Failed with: %s", err)
+	}
+}
+
+func TestNewClientRestConfigError(t *testing.T) {
+	_, err := newClientRestConfig("does-not-exist", "", rest.InClusterConfig)
+
+	if err == nil {
+		t.Errorf("Expected to fail with non-existent kubeconfig")
+	}
+}
+
+func TestNewClientRestConfigWithKubeconfigPath(t *testing.T) {
+	_, err := newClientRestConfig(filepath.Join(FIXTURES_DIR, "kube.config.basic"), "", rest.InClusterConfig)
+	if err != nil {
+		t.Fatalf("Failed with: %s", err)
+	}
+}
+
+func TestNewClientRestConfigMultipleFiles(t *testing.T) {
+	env := setupEnv(t, map[string]string{
+		"KUBECONFIG": filepath.Join(FIXTURES_DIR, "kube.config.empty") + ":" + filepath.Join(FIXTURES_DIR, "kube.config.basic"),
+	})
+	defer env.reset()
+
+	if _, err := newClientRestConfig("", "", rest.InClusterConfig); err != nil {
+		t.Fatalf("Failed with: %s", err)
+	}
+}
+
+func TestNewClientRestConfigWithContext(t *testing.T) {
+	expectedContext := "test-context"
+	expectedHost := "https://test-cluster"
+
+	config, err := newClientRestConfig(filepath.Join(FIXTURES_DIR, "kube.config.context"), expectedContext, rest.InClusterConfig)
+	if err != nil {
+		t.Fatalf("Failed to create kubeCollector from fake client with context %s: %s", expectedContext, err)
+	}
+
+	if config.Host != expectedHost {
+		t.Fatalf("Expected host from context %s to be: %s, got %s instead", expectedContext, expectedHost, config.Host)
+	}
+}
+
+func TestNewClientRestConfigContextMissing(t *testing.T) {
+	expectedContext := "non-existent"
+
+	_, err := newClientRestConfig(filepath.Join(FIXTURES_DIR, "kube.config.context"), expectedContext, rest.InClusterConfig)
+	if err == nil {
+		t.Fatalf("Expected to fail when uisng non-existent context: %s", expectedContext)
+	}
+}
+
+func TestNewClientRestConfigInCluster(t *testing.T) {
+	expectedHost := "test-host"
+	inClusterFn := func() (*rest.Config, error) {
+		return &rest.Config{Host: expectedHost}, nil
+	}
+
+	cfg, err := newClientRestConfig("", "", inClusterFn)
+	if err != nil {
+		t.Fatalf("Failed to create in-cluster config: %s", err)
+	}
+	if cfg.Host != expectedHost {
+		t.Fatalf("Expected %s host, instead got: %s", expectedHost, cfg.Host)
+	}
+}
+
 type env struct {
 	initialVals  map[string]string
 	initialState map[string]bool