Java/JVM Configuration

Glance provides native support for Java applications with automatic HttpsURLConnection overrides.

Automatic Setup (Java 8+)

Glance includes a specialized Java agent that automatically configures HttpsURLConnection to:

• Trust Glance's CA certificate
• Route traffic through the proxy
• Work with already-running applications

How It Works

1. Glance detects running Java processes
2. Attaches bytecode instrumentation
3. Overrides HttpsURLConnection behavior
4. No code changes required

Manual Configuration

If automatic setup doesn't work, you can manually configure the JVM.

Method 1: JVM Arguments

Start your Java application with these arguments:

java -Dhttp.proxyHost=localhost \
     -Dhttp.proxyPort=15500 \
     -Dhttps.proxyHost=localhost \
     -Dhttps.proxyPort=15500 \
     -jar your-application.jar

Method 2: System Properties

Set properties programmatically:

System.setProperty("http.proxyHost", "localhost");
System.setProperty("http.proxyPort", "15500");
System.setProperty("https.proxyHost", "localhost");
System.setProperty("https.proxyPort", "15500");

Method 3: Proxy Class

Use Java's Proxy class:

import java.net.*;

Proxy proxy = new Proxy(
    Proxy.Type.HTTP,
    new InetSocketAddress("localhost", 15500)
);

URL url = new URL("https://api.example.com/users");
HttpURLConnection conn = (HttpURLConnection) url.openConnection(proxy);

Certificate Trust

Option 1: Import to JVM Keystore

# Export Glance CA certificate
curl http://localhost:15501/ca.crt -o glance-ca.crt

# Import to JVM keystore (replace JDK_PATH)
keytool -import -trustcacerts -alias glance \
        -file glance-ca.crt \
        -keystore $JDK_PATH/lib/security/cacerts \
        -storepass changeit

Option 2: Custom TrustManager

Create a custom TrustManager that trusts Glance's certificate:

import javax.net.ssl.*;
import java.security.cert.*;

// For development only - do not use in production!
TrustManager[] trustAllCerts = new TrustManager[] {
    new X509TrustManager() {
        public X509Certificate[] getAcceptedIssuers() { return null; }
        public void checkClientTrusted(X509Certificate[] certs, String authType) { }
        public void checkServerTrusted(X509Certificate[] certs, String authType) { }
    }
};

SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

⚠️ Warning: Only use this in development. Never disable certificate validation in production!

Framework-Specific Configuration

Spring Boot

Add to application.properties:

http.proxy.host=localhost
http.proxy.port=15500
https.proxy.host=localhost
https.proxy.port=15500

Or configure via RestTemplate:

@Configuration
public class ProxyConfig {
    @Bean
    public RestTemplate restTemplate() {
        SimpleClientHttpRequestFactory requestFactory =
            new SimpleClientHttpRequestFactory();

        Proxy proxy = new Proxy(
            Proxy.Type.HTTP,
            new InetSocketAddress("localhost", 15500)
        );
        requestFactory.setProxy(proxy);

        return new RestTemplate(requestFactory);
    }
}

Apache HttpClient

import org.apache.http.HttpHost;
import org.apache.http.impl.client.HttpClients;

HttpHost proxy = new HttpHost("localhost", 15500);
CloseableHttpClient httpClient = HttpClients.custom()
    .setProxy(proxy)
    .build();

OkHttp

import okhttp3.*;

Proxy proxy = new Proxy(
    Proxy.Type.HTTP,
    new InetSocketAddress("localhost", 15500)
);

OkHttpClient client = new OkHttpClient.Builder()
    .proxy(proxy)
    .build();

Testing

Verify your Java app is using the proxy:

import java.net.*;

public class ProxyTest {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://api.github.com/users");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        int responseCode = conn.getResponseCode();
        System.out.println("Response Code: " + responseCode);

        // This request should appear in Glance dashboard
    }
}

Troubleshooting

Certificate Errors

If you see SSLHandshakeException:

1. Verify CA certificate is imported
2. Check certificate alias exists
3. Ensure using correct keystore

Proxy Not Used

If traffic doesn't appear in Glance:

1. Check proxy properties are set
2. Verify no other proxy configured
3. Some libraries ignore system properties

ClassLoader Issues

If automatic agent fails:

1. Check Java version (8+ required)
2. Try manual configuration instead
3. Check for SecurityManager restrictions

Next Steps

• Client Configuration - Other platforms
• Troubleshooting - Common issues
• Examples - Sample code