Forward Java log configuration to Rust log subscriber

README.md

@@ -73,8 +73,7 @@ For example of how to setup your project, check out [ngrok-java-demo](https://gi
 
 # Documentation
 
-# Quickstart
-
+## Quickstart
 
 ```java
 import com.ngrok.Session;
@@ -114,6 +113,19 @@ public class Echo {
 }
 ```
 
+## Configuring Logging
+Log level is set from the your `slf4j` implementation's configuration. This level must be assigned before creating a session, as it is read on creation.
+
+As an example, to configure `slf4j-simple`, you can do:
+```java
+   System.setProperty("org.slf4j.simpleLogger.log.com.ngrok.Runtime", "debug");
+```
+
+You can then log through the `Runtime` API:
+```java
+   Runtime.getLogger().log("info", "myClass", "Hello World");
+```
+
 # License
 
 This project is licensed under either of

ngrok-java-native/pom.xml

@@ -22,6 +22,12 @@
             <artifactId>slf4j-api</artifactId>
             <version>${slf4j.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j.version}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>

ngrok-java-native/src/lib.rs

@@ -13,7 +13,7 @@ use futures::TryStreamExt;
 use once_cell::sync::OnceCell;
 use std::{str::FromStr, sync::MutexGuard, time::Duration};
 use tokio::{io::AsyncReadExt, io::AsyncWriteExt, runtime::Runtime};
-use tracing::metadata::LevelFilter;
+use tracing::{level_filters::LevelFilter, Level};
 use tracing_subscriber::{prelude::__tracing_subscriber_SubscriberExt, util::SubscriberInitExt};
 
 use jaffi_support::{
@@ -69,9 +69,12 @@ impl<'local> com_ngrok::RuntimeRs<'local> for RuntimeRsImpl<'local> {
                     .expect("cannot get logger ref");
                 LOGGER.get_or_init(|| logref);
 
+                let log_lvl: Level =
+                    Level::from_str(&logger.get_level(self.env)).expect("invalid log level");
+                let level_filter: LevelFilter = log_lvl.into();
                 tracing_subscriber::registry()
                     .with(TracingLoggingLayer)
-                    .with(LevelFilter::TRACE)
+                    .with(level_filter)
                     .try_init()
                     .expect("cannot init logging");
             }

ngrok-java-native/src/main/java/com/ngrok/NativeSession.java

@@ -9,7 +9,7 @@ public class NativeSession implements Session {
     static {
         try {
             Runtime.load();
-            Runtime.init(new Runtime.Logger());
+            Runtime.init(Runtime.getLogger());
         } catch (Throwable th) {
             // TODO better error handling here?
             th.printStackTrace();

ngrok-java-native/src/main/java/com/ngrok/Runtime.java

@@ -1,6 +1,7 @@
 package com.ngrok;
 
 import org.slf4j.LoggerFactory;
+import org.slf4j.event.Level;
 
 import java.io.File;
 import java.io.IOException;
@@ -9,7 +10,12 @@
 import java.util.Locale;
 
 class Runtime {
-    private static final org.slf4j.Logger logger = LoggerFactory.getLogger(Runtime.class);
+
+    private static final Logger LOGGER = new Logger(); 
+
+    public static Logger getLogger() {
+        return LOGGER;
+    }
 
     private static String getLibname() {
         // TODO better logic here/use lib
@@ -34,10 +40,7 @@ public static void load() {
         File temp = new File(temporaryDir, filename);
         try (InputStream is = Runtime.class.getResourceAsStream("/" + filename)) {
             Files.copy(is, temp.toPath(), StandardCopyOption.REPLACE_EXISTING);
-        } catch (IOException e) {
-            temp.delete();
-            throw new RuntimeException(e);
-        } catch (NullPointerException e) {
+        } catch (IOException | NullPointerException e) {
             temp.delete();
             throw new RuntimeException(e);
         }
@@ -70,17 +73,27 @@ private static boolean isPosixCompliant() {
     static native void init(Logger logger);
 
     static class Logger {
+        private static final org.slf4j.Logger logger = LoggerFactory.getLogger(Runtime.class);
         private static final String format = "[{}] {}";
 
-        public void log(String level, String target, String message) {
-            switch (level) {
-                case "TRACE" -> logger.trace(format, target, message);
-                case "DEBUG" -> logger.debug(format, target, message);
-                case "INFO" -> logger.info(format, target, message);
-                case "WARN" -> logger.warn(format, target, message);
-                case "ERROR" -> logger.error(format, target, message);
-                default -> logger.debug("{}: [{}] {}", level, target, message);
+        private Logger() { }
+
+        public String getLevel() {
+            Level logLevel = Level.INFO;
+
+            Level[] levels = new Level[] {Level.ERROR, Level.WARN, Level.INFO, Level.DEBUG, Level.TRACE};
+            for (Level level : levels) {
+                if (logger.isEnabledForLevel(level)) {
+                    logLevel = level;
+                }
             }
+
+            return logLevel.toString();
+        }
+
+        public void log(String level, String target, String message) {
+            Level lvl = Level.valueOf(level.toUpperCase()); 
+            logger.atLevel(lvl).log(format, target, message);
         }
     }
 }

ngrok-java-native/src/test/java/com/ngrok/DataTest.java

@@ -1,12 +1,20 @@
 package com.ngrok;
 
+import org.junit.Before;
 import org.junit.Test;
 
 import java.nio.ByteBuffer;
 
 import static org.junit.Assert.*;
 
 public class DataTest {
+
+    @Before
+    public void setup() {
+        System.setProperty("org.slf4j.simpleLogger.log.com.ngrok.Runtime", "trace");
+
+    }
+
     @Test
     public void testSessionClose() throws Exception {
         try (var session = Session.connect(Session.newBuilder().metadata("java-session"))) {
@@ -19,7 +27,7 @@ public void testTunnelClose() throws Exception {
         try (var session = Session.connect(Session.newBuilder());
             var tunnel = session.httpTunnel(new HttpTunnel.Builder().metadata("java-tunnel"))) {
             assertEquals("java-tunnel", tunnel.getMetadata());
-            System.out.println(tunnel.getUrl());
+            Runtime.getLogger().log("info", "session", tunnel.getUrl());
         }
     }
 

ngrok-java-native/src/test/java/com/ngrok/ForwardTest.java

@@ -6,6 +6,7 @@
 import static org.junit.Assert.assertTrue;
 
 public class ForwardTest {
+    // @Test
     public void testForward() throws Exception {
         var session = Session.connect(Session.newBuilder());
         assertNotNull(session);