Handling and logging fatal errors (#542)

* handling and logging fatal errors

* release notes

* [Gradle Release Plugin] - new version commit:  '3.25.9-snapshot'.

Author: mageddo

RELEASE-NOTES.md

@@ -1,3 +1,6 @@
+## 3.25.9
+* Handling and logging fatal errors #480
+
 ## 3.25.8
 * SolverRemote: Exclude remote servers with open circuits. #526
 

gradle.properties

@@ -1 +1 @@
-version=3.25.8-snapshot
+version=3.25.9-snapshot

src/main/java/com/mageddo/dnsproxyserver/App.java

@@ -7,10 +7,14 @@
 import com.mageddo.dnsproxyserver.config.dataprovider.vo.ConfigFlag;
 import com.mageddo.dnsproxyserver.di.Context;
 import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.ClassUtils;
+import org.apache.commons.lang3.exception.ExceptionUtils;
 
 import java.nio.file.Files;
 import java.nio.file.Paths;
 
+@Slf4j
 public class App {
 
   private final String[] args;
@@ -26,7 +30,21 @@ public static void main(String[] args) {
   }
 
   void start() {
+    try {
+      log.trace("status=starting");
+      this.mustStart();
+    } catch (SystemExitException e) {
+      throw e;
+    } catch (Throwable e) {
+      log.error(
+        "status=fatalError, action=exit, msg={}, class={}",
+        ExceptionUtils.getMessage(e), ClassUtils.getSimpleName(e), e
+      );
+      this.exitWithError(128);
+    }
+  }
 
+  void mustStart() {
     this.flags = ConfigFlag.parse(this.args);
 
     this.checkHiddenCommands();
@@ -46,6 +64,7 @@ void checkHiddenCommands() {
     if (this.flags.isCreateTmpDir()) {
       this.createTmpDirIfNotExists();
     }
+    log.trace("status=checked");
   }
 
   Config findConfig(String[] args) {
@@ -54,7 +73,9 @@ Config findConfig(String[] args) {
   }
 
   void setupLogs() {
+    log.trace("status=configuring");
     new LogSettings().setupLogs(this.config);
+    log.trace("status=configured");
   }
 
   void startContext() {
@@ -69,15 +90,34 @@ void checkExitCommands() {
     if (flags.isHelp() || flags.isVersion()) {
       exitGracefully();
     }
+    log.trace("status=checked");
   }
 
   void exitGracefully() {
     System.exit(0);
   }
 
+  void exitWithError(int errorCode) {
+    System.exit(errorCode);
+  }
+
   @SneakyThrows
   void createTmpDirIfNotExists() {
     final var tmpDir = Paths.get(System.getProperty("java.io.tmpdir"));
     Files.createDirectories(tmpDir);
   }
+
+  Config getConfig() {
+    return config;
+  }
+
+  int getDnsServerPort() {
+    return getConfig().getDnsServerPort();
+  }
+
+  static class SystemExitException extends RuntimeException {
+    public SystemExitException(String reason) {
+      super(reason);
+    }
+  }
 }

src/test/java/com/mageddo/dnsproxyserver/AppCompTest.java

@@ -7,6 +7,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.never;
@@ -68,9 +69,30 @@ void mustCreateTmpDirIfNotExists() {
 
   }
 
+  @Test
+  void mustHandleFatalErrors() {
+    // arrange
+    final var args = new String[]{"--create-tmp-dir"};
+    this.setupStub(args);
+
+    doThrow(new IllegalAccessError("mocked fatal error"))
+      .when(this.app)
+      .checkHiddenCommands()
+    ;
+    doNothing()
+      .when(this.app)
+      .exitWithError(anyInt())
+    ;
+
+    // act
+    this.app.start();
+
+    verify(this.app).exitWithError(anyInt());
+
+  }
 
   RuntimeException mockExitMethod() {
-    final var expectedException = new RuntimeException("must exit");
+    final var expectedException = new App.SystemExitException("testing");
     doThrow(expectedException)
       .when(this.app)
       .exitGracefully()