Make tunnel-client max HTTP content length configurable (#3034)

common/src/main/java/com/taobao/arthas/common/ArthasConstants.java

@@ -16,6 +16,35 @@ public class ArthasConstants {
 
     public static final int MAX_HTTP_CONTENT_LENGTH = 1024 * 1024 * 10;
 
+    /**
+     * System property to override the max HTTP content length used by the
+     * tunnel-client when proxying responses (e.g. JFR recording downloads)
+     * back to the tunnel-server. The value is in bytes; default is
+     * {@link #MAX_HTTP_CONTENT_LENGTH} (10 MB). See issue #3034.
+     */
+    public static final String TUNNEL_CLIENT_MAX_HTTP_CONTENT_LENGTH_PROPERTY = "arthas.tunnel.client.max-http-content-length";
+
+    /**
+     * Resolve the configured tunnel-client max HTTP content length. Falls back
+     * to {@link #MAX_HTTP_CONTENT_LENGTH} when the system property is unset,
+     * non-numeric, or non-positive.
+     */
+    public static int getTunnelClientMaxHttpContentLength() {
+        String value = System.getProperty(TUNNEL_CLIENT_MAX_HTTP_CONTENT_LENGTH_PROPERTY);
+        if (value == null || value.isEmpty()) {
+            return MAX_HTTP_CONTENT_LENGTH;
+        }
+        try {
+            int parsed = Integer.parseInt(value.trim());
+            if (parsed > 0) {
+                return parsed;
+            }
+        } catch (NumberFormatException ignore) {
+            // fall through to default
+        }
+        return MAX_HTTP_CONTENT_LENGTH;
+    }
+
     public static final String ARTHAS_OUTPUT = "arthas-output";
 
     public static final String APP_NAME = "app-name";

tunnel-client/pom.xml

@@ -57,6 +57,16 @@
 			<artifactId>netty-codec-http</artifactId>
 		</dependency>
 
+		<dependency>
+			<groupId>org.junit.vintage</groupId>
+			<artifactId>junit-vintage-engine</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 </project>

tunnel-client/src/main/java/com/alibaba/arthas/tunnel/client/ProxyClient.java

@@ -60,7 +60,8 @@ public SimpleHttpResponse query(String targetUrl) throws InterruptedException {
                 @Override
                 protected void initChannel(LocalChannel ch) {
                     ChannelPipeline p = ch.pipeline();
-                    p.addLast(new HttpClientCodec(), new HttpObjectAggregator(ArthasConstants.MAX_HTTP_CONTENT_LENGTH),
+                    p.addLast(new HttpClientCodec(),
+                            new HttpObjectAggregator(ArthasConstants.getTunnelClientMaxHttpContentLength()),
                             new HttpProxyClientHandler(httpResponsePromise));
                 }
             });

tunnel-client/src/test/java/com/taobao/arthas/common/ArthasConstantsTest.java

@@ -0,0 +1,67 @@
+package com.taobao.arthas.common;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Tests for the configurable tunnel-client max HTTP content length introduced
+ * for issue #3034 ("Unable to download JFR recordings larger than 10MB via
+ * Tunnel Server").
+ */
+public class ArthasConstantsTest {
+
+    private static final String PROPERTY = ArthasConstants.TUNNEL_CLIENT_MAX_HTTP_CONTENT_LENGTH_PROPERTY;
+
+    private String originalValue;
+
+    @Before
+    public void saveProperty() {
+        originalValue = System.getProperty(PROPERTY);
+        System.clearProperty(PROPERTY);
+    }
+
+    @After
+    public void restoreProperty() {
+        if (originalValue == null) {
+            System.clearProperty(PROPERTY);
+        } else {
+            System.setProperty(PROPERTY, originalValue);
+        }
+    }
+
+    @Test
+    public void defaultsToTenMegabytesWhenPropertyMissing() {
+        assertEquals(ArthasConstants.MAX_HTTP_CONTENT_LENGTH,
+                ArthasConstants.getTunnelClientMaxHttpContentLength());
+    }
+
+    @Test
+    public void honoursConfiguredPropertyValue() {
+        int oneHundredMb = 100 * 1024 * 1024;
+        System.setProperty(PROPERTY, Integer.toString(oneHundredMb));
+
+        assertEquals(oneHundredMb, ArthasConstants.getTunnelClientMaxHttpContentLength());
+    }
+
+    @Test
+    public void fallsBackToDefaultWhenPropertyIsNotANumber() {
+        System.setProperty(PROPERTY, "not-a-number");
+
+        assertEquals(ArthasConstants.MAX_HTTP_CONTENT_LENGTH,
+                ArthasConstants.getTunnelClientMaxHttpContentLength());
+    }
+
+    @Test
+    public void fallsBackToDefaultWhenPropertyIsNotPositive() {
+        System.setProperty(PROPERTY, "0");
+        assertEquals(ArthasConstants.MAX_HTTP_CONTENT_LENGTH,
+                ArthasConstants.getTunnelClientMaxHttpContentLength());
+
+        System.setProperty(PROPERTY, "-1");
+        assertEquals(ArthasConstants.MAX_HTTP_CONTENT_LENGTH,
+                ArthasConstants.getTunnelClientMaxHttpContentLength());
+    }
+}