Support KUBECONFIG environment variable

- Watch for changes in file(s) indicated by `KUBECONFIG` when it's set
- Warn when multiple config files are specified in `KUBECONFIG`,
  since the Kubernetes client library we are using doesn't support this use case

Closes #3382

Signed-off-by: David Thompson <davthomp@redhat.com>

Author: datho7561

src/explorer.ts

@@ -30,7 +30,34 @@ import { Progress } from './util/progress';
 import { FileContentChangeNotifier, WatchUtil } from './util/watch';
 import { vsCommand } from './vscommand';
 
-const kubeConfigFolder: string = path.join(Platform.getUserHomePath(), '.kube');
+/**
+ * Returns the list of kube config files:
+ * - If KUBECONFIG is not set, just ~/.kube/config
+ * - If KUBECONFIG is set, follows the semantics for specifying multiple config files described here:
+ *   https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/#append-home-kube-config-to-your-kubeconfig-environment-variable
+ *   BUT: it shows an error if multiple configs are specified, since the Kubernetes client we are using doesn't support this use case.
+ */
+function getKubeConfigFiles(): string[] {
+    if (process.env.KUBECONFIG) {
+        let configuredFiles: string[] = [];
+        if (process.platform === 'win32') {
+            configuredFiles = process.env.KUBECONFIG.split(';');
+        } else {
+            configuredFiles = process.env.KUBECONFIG.split(':');
+        }
+        if (configuredFiles.length > 1) {
+            void window.showWarningMessage('KUBECONFIG specifies multiple files. Unfortunately, the extension doesn\'t work properly with this setup. Expect things to break.');
+        }
+        const filesThatExist: string[] = [];
+        for (const configFile of configuredFiles) {
+            if (fs.existsSync(configFile)) {
+                filesThatExist.push(configFile);
+            }
+        }
+        return filesThatExist;
+    }
+    return [path.join(Platform.getUserHomePath(), '.kube', 'config')];
+}
 
 type ExplorerItem = KubernetesObject | Helm.HelmRelease | Context | TreeItem;
 
@@ -42,7 +69,7 @@ type PackageJSON = {
 const CREATE_OR_SET_PROJECT_ITEM = {
     label: 'Create new or set active Project',
     command: {
-        title: 'Create new or ser active Project',
+        title: 'Create new or set active Project',
         command: 'openshift.project.set'
     }
 };
@@ -52,7 +79,7 @@ export class OpenShiftExplorer implements TreeDataProvider<ExplorerItem>, Dispos
 
     private treeView: TreeView<ExplorerItem>;
 
-    private fsw: FileContentChangeNotifier;
+    private kubeConfigWatchers: FileContentChangeNotifier[];
     private kubeContext: Context;
     private kubeConfig: KubeConfigUtils;
 
@@ -70,22 +97,25 @@ export class OpenShiftExplorer implements TreeDataProvider<ExplorerItem>, Dispos
             // ignore config loading error and let odo report it on first call
         }
         try {
-            this.fsw = WatchUtil.watchFileForContextChange(kubeConfigFolder, 'config');
+            const kubeconfigFiles = getKubeConfigFiles();
+            this.kubeConfigWatchers = kubeconfigFiles.map(kubeconfigFile => WatchUtil.watchFileForContextChange(path.dirname(kubeconfigFile), path.basename(kubeconfigFile)));
         } catch (err) {
             void window.showWarningMessage('Couldn\'t install watcher for Kubernetes configuration file. OpenShift Application Explorer view won\'t be updated automatically.');
         }
-        this.fsw?.emitter?.on('file-changed', () => {
-            const ku2 = new KubeConfigUtils();
-            const newCtx = ku2.getContextObject(ku2.currentContext);
-            if (!this.kubeContext
-                || (this.kubeContext.cluster !== newCtx.cluster
-                    || this.kubeContext.user !== newCtx.user
-                    || this.kubeContext.namespace !== newCtx.namespace)) {
-                this.refresh();
-            }
-            this.kubeContext = newCtx;
-            this.kubeConfig = ku2;
-        });
+        for (const fsw of this.kubeConfigWatchers) {
+            fsw.emitter?.on('file-changed', () => {
+                const ku2 = new KubeConfigUtils();
+                const newCtx = ku2.getContextObject(ku2.currentContext);
+                if (Boolean(this.kubeContext) !== Boolean(newCtx)
+                    || (this.kubeContext.cluster !== newCtx.cluster
+                        || this.kubeContext.user !== newCtx.user
+                        || this.kubeContext.namespace !== newCtx.namespace)) {
+                    this.refresh();
+                }
+                this.kubeContext = newCtx;
+                this.kubeConfig = ku2;
+            });
+        }
         this.treeView = window.createTreeView<ExplorerItem>('openshiftProjectExplorer', {
             treeDataProvider: this,
         });
@@ -110,7 +140,7 @@ export class OpenShiftExplorer implements TreeDataProvider<ExplorerItem>, Dispos
                 contextValue: 'openshift.openConfigFile',
                 label: element.label,
                 collapsibleState: TreeItemCollapsibleState.None,
-                tooltip: 'Default KubeConfig',
+                tooltip: element.label as string,
                 description: element.description,
                 iconPath: new ThemeIcon('file')
             };
@@ -175,11 +205,8 @@ export class OpenShiftExplorer implements TreeDataProvider<ExplorerItem>, Dispos
                 await Odo.Instance.getProjects();
                 result = [this.kubeContext];
                 if (this.kubeContext) {
-                    const homeDir = this.kubeConfig.findHomeDir();
-                    if (homeDir){
-                        const config = path.join(homeDir, '.kube', 'config');
-                        result.unshift({label: 'Default KubeConfig', description: `${config}`})
-                    }
+                    const config = getKubeConfigFiles();
+                    result.unshift({label: process.env.KUBECONFIG ? 'Custom KubeConfig' : 'Default KubeConfig', description: config.join(':')})
                 }
             } catch (err) {
                 // ignore because ether server is not accessible or user is logged out
@@ -246,7 +273,9 @@ export class OpenShiftExplorer implements TreeDataProvider<ExplorerItem>, Dispos
     }
 
     dispose(): void {
-        this.fsw?.watcher?.close();
+        for (const fsw of this.kubeConfigWatchers) {
+            fsw?.watcher?.close();
+        }
         this.treeView.dispose();
     }
 

src/util/kubeUtils.ts

@@ -3,11 +3,11 @@
  *  Licensed under the MIT License. See LICENSE file in the project root for license information.
  *-----------------------------------------------------------------------------------------------*/
 
+import { KubeConfig, findHomeDir, loadYaml } from '@kubernetes/client-node';
+import { Cluster, User } from '@kubernetes/client-node/dist/config_types';
 import * as fs from 'fs';
 import * as path from 'path';
 import { QuickPickItem } from 'vscode';
-import { KubeConfig, findHomeDir, loadYaml } from '@kubernetes/client-node';
-import { User, Cluster } from '@kubernetes/client-node/dist/config_types';
 
 function fileExists(file: string): boolean {
     try {