fix: only notify change when kube config exists, isnt empty and complete (#190)

src/main/java/com/redhat/devtools/intellij/common/utils/ConfigWatcher.java

@@ -12,19 +12,24 @@
 
 import com.intellij.openapi.diagnostic.Logger;
 import io.fabric8.kubernetes.api.model.Config;
+import io.fabric8.kubernetes.client.internal.KubeConfigUtils;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.IOException;
 import java.nio.file.FileSystems;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardWatchEventKinds;
 import java.nio.file.WatchEvent;
 import java.nio.file.WatchKey;
 import java.nio.file.WatchService;
+import java.util.function.Consumer;
 
 public class ConfigWatcher implements Runnable {
 
+    private static final Logger LOG = Logger.getInstance(ConfigWatcher.class);
+
     private final Path config;
     protected Listener listener;
 
@@ -43,8 +48,7 @@ public ConfigWatcher(Path config, Listener listener) {
 
     @Override
     public void run() {
-        runOnConfigChange(() -> {
-            Config config = loadConfig();
+        runOnConfigChange((Config config) -> {
             if (config != null) {
                 listener.onUpdate(this, config);
             }
@@ -59,14 +63,13 @@ protected Config loadConfig() {
         }
     }
 
-    private void runOnConfigChange(Runnable runnable) {
+    private void runOnConfigChange(Consumer<Config> consumer) {
         try (WatchService service = newWatchService()) {
             registerWatchService(service);
             WatchKey key;
             while ((key = service.take()) != null) {
                 key.pollEvents().stream()
-                        .filter(this::isConfigPath)
-                        .forEach((Void) -> runnable.run());
+                        .forEach((event) -> consumer.accept(loadConfig(getPath(event))));
                 key.reset();
             }
         } catch (IOException | InterruptedException e) {
@@ -90,11 +93,43 @@ private void registerWatchService(WatchService service) throws IOException {
                 service);
     }
 
-    protected boolean isConfigPath(WatchEvent<?> event) {
-        Path path = getWatchedPath().resolve((Path) event.context());
+    protected boolean isConfigPath(Path path) {
         return path.equals(config);
     }
 
+    /**
+     * Returns {@link Config} for the given path if the kube config file
+     * <ul>
+     *     <li>exists and</li>
+     *     <li>is not empty and</li>
+     *     <li>is valid yaml</li>
+     * </ul>
+     * Returns {@code null} otherwise.
+     *
+     * @param path the path to the kube config
+     * @return returns true if the kube config that the event points to exists, is not empty and is valid yaml
+     */
+    private Config loadConfig(Path path) {
+        if (path == null) {
+            return null;
+        }
+        try {
+            if (Files.exists(path)
+                    && isConfigPath(path)
+                    && Files.size(path) > 0) {
+                return KubeConfigUtils.parseConfig(path.toFile());
+            }
+        } catch (Exception e) {
+            // only catch
+            LOG.warn("Could not load kube config at " + path.toAbsolutePath(), e);
+        }
+        return null;
+    }
+
+    private Path getPath(WatchEvent<?> event) {
+        return getWatchedPath().resolve((Path) event.context());
+    }
+
     private Path getWatchedPath() {
         return config.getParent();
     }