Added additional checks on the command used in the Exec plugin in a kubeconfig (#1013)

- Added check to see if the program being referenced in the command field of the
exec object in the User construct exists. If it doesn't an error will be raised.
If more than 1 context is selected when adding a kubeconfig then valid contexts
will be added and any with an error will not be.

Signed-off-by: Steve Richards <srichards@mirantis.com>

Co-authored-by: Steve Richards <srichards@mirantis.com>

src/common/custom-errors.ts

@@ -0,0 +1,12 @@
+export class ExecValidationNotFoundError extends Error {
+  constructor(execPath: string, isAbsolute: boolean) {
+    super(`User Exec command "${execPath}" not found on host.`);
+    let message = `User Exec command "${execPath}" not found on host.`;
+    if (!isAbsolute) {
+      message += ` Please ensure binary is found in PATH or use absolute path to binary in Kubeconfig`;
+    }
+    this.message = message; 
+    this.name = this.constructor.name;
+    Error.captureStackTrace(this, this.constructor);
+  }
+}

src/common/kube-helpers.ts

@@ -4,6 +4,8 @@ import path from "path"
 import os from "os"
 import yaml from "js-yaml"
 import logger from "../main/logger";
+import commandExists from "command-exists";
+import { ExecValidationNotFoundError } from "./custom-errors";
 
 export const kubeConfigDefaultPath = path.join(os.homedir(), '.kube', 'config');
 
@@ -140,3 +142,28 @@ export function getNodeWarningConditions(node: V1Node) {
     c.status.toLowerCase() === "true" && c.type !== "Ready" && c.type !== "HostUpgrades"
   )
 }
+
+/**
+ * Validates kubeconfig supplied in the add clusters screen. At present this will just validate
+ * the User struct, specifically the command passed to the exec substructure. 
+ */ 
+export function validateKubeConfig (config: KubeConfig) {
+  // we only receive a single context, cluster & user object here so lets validate them as this
+  // will be called when we add a new cluster to Lens
+  logger.debug(`validateKubeConfig: validating kubeconfig - ${JSON.stringify(config)}`);
+
+  // Validate the User Object
+  const user = config.getCurrentUser();  
+  if (user.exec) {
+    const execCommand = user.exec["command"];
+    // check if the command is absolute or not
+    const isAbsolute = path.isAbsolute(execCommand);
+    // validate the exec struct in the user object, start with the command field
+    logger.debug(`validateKubeConfig: validating user exec command - ${JSON.stringify(execCommand)}`);
+
+    if (!commandExists.sync(execCommand)) {
+      logger.debug(`validateKubeConfig: exec command ${String(execCommand)} in kubeconfig ${config.currentContext} not found`);
+      throw new ExecValidationNotFoundError(execCommand, isAbsolute);
+    }
+  }
+}