chore(addons): allow local k8s environment in development mode [r8s-1148] (#3177)

api/kubernetes/cli/client.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -373,7 +374,7 @@ func (factory *ClientFactory) CreateRemoteMetricsClient(endpoint *portainer.Endp
 }
 
 func buildLocalConfig() (*rest.Config, error) {
-	config, err := rest.InClusterConfig()
+	config, err := buildLocalRestConfig()
 	if err != nil {
 		return nil, err
 	}
@@ -384,6 +385,17 @@ func buildLocalConfig() (*rest.Config, error) {
 	return config, nil
 }
 
+// buildLocalRestConfig returns the in-cluster config, or a config built from
+// the kubeconfig at DEV_KUBECONFIG_PATH so developers can run the server
+// locally against a local cluster (same convention as the agent).
+func buildLocalRestConfig() (*rest.Config, error) {
+	if devKubeConfigPath := os.Getenv("DEV_KUBECONFIG_PATH"); devKubeConfigPath != "" {
+		return clientcmd.BuildConfigFromFlags("", devKubeConfigPath)
+	}
+
+	return rest.InClusterConfig()
+}
+
 func (factory *ClientFactory) MigrateEndpointIngresses(e *portainer.Endpoint, datastore dataservices.DataStore, cli *KubeClient) error {
 	return datastore.UpdateTx(func(tx dataservices.DataStoreTx) error {
 		environment, err := tx.Endpoint().Endpoint(e.ID)

api/kubernetes/cli/client_test.go

@@ -1,7 +1,12 @@
 package cli
 
 import (
+	"os"
 	"testing"
+
+	"github.com/portainer/portainer/api/filesystem"
+	"github.com/stretchr/testify/require"
+	"k8s.io/client-go/rest"
 )
 
 func TestClearUserClientCache(t *testing.T) {
@@ -21,3 +26,42 @@ func TestClearUserClientCache(t *testing.T) {
 		t.Errorf("Expected not to find client cache for user after clear")
 	}
 }
+
+func TestBuildLocalRestConfig(t *testing.T) {
+	t.Run("uses the kubeconfig at DEV_KUBECONFIG_PATH when set", func(t *testing.T) {
+		kubeconfigPath := filesystem.JoinPaths(t.TempDir(), "kubeconfig")
+		require.NoError(t, os.WriteFile(kubeconfigPath, []byte(`
+apiVersion: v1
+kind: Config
+clusters:
+- name: local
+  cluster:
+    server: https://127.0.0.1:26443
+    insecure-skip-tls-verify: true
+contexts:
+- name: local
+  context:
+    cluster: local
+    user: local
+current-context: local
+users:
+- name: local
+  user:
+    token: fake-token
+`), 0o600))
+		t.Setenv("DEV_KUBECONFIG_PATH", kubeconfigPath)
+
+		config, err := buildLocalRestConfig()
+		require.NoError(t, err)
+		require.Equal(t, "https://127.0.0.1:26443", config.Host)
+	})
+
+	t.Run("falls back to the in-cluster config when unset", func(t *testing.T) {
+		t.Setenv("DEV_KUBECONFIG_PATH", "")
+		t.Setenv("KUBERNETES_SERVICE_HOST", "")
+		t.Setenv("KUBERNETES_SERVICE_PORT", "")
+
+		_, err := buildLocalRestConfig()
+		require.ErrorIs(t, err, rest.ErrNotInCluster)
+	})
+}