Can Tomcat reload its SSL certificate without being restarted?

Solution 1:

You can restart individual Tomcat connector i.e. port restart like 8443 is possible after you change your jssecacert file.

Here is the complete code/method that I am using to restart tomcat connectors after I add/delete certificates.

// Stop and restart the SSL connection so that the tomcat server will
// re-read the certificates from the truststore file.
public void refreshTrustStore() throws Exception 
{
    try 
    {
        //following line should be replaced based on where you get your port number. You may pass in as argument to this method
        String httpsPort = configurationManager.getHttpsPort();
        String objectString = "*:type=Connector,port=" + httpsPort + ",*";

        final ObjectName objectNameQuery = new ObjectName(objectString); 

        for (final MBeanServer server: MBeanServerFactory.findMBeanServer(null))
        {
            if (!server.queryNames(objectNameQuery, null).isEmpty())
            {
                MBeanServer mbeanServer = server;
                ObjectName objectName = (ObjectName) server.queryNames(objectNameQuery, null).toArray()[0];

                mbeanServer.invoke(objectName, "stop", null, null);

                // Polling sleep to reduce delay to safe minimum.
                // Use currentTimeMillis() over nanoTime() to avoid issues
                // with migrating threads across sleep() calls.
                long start = System.currentTimeMillis();
                // Maximum of 6 seconds, 3x time required on an idle system.
                long max_duration = 6000L;
                long duration = 0L;
                do
                {
                    try
                    {
                        Thread.sleep(100);
                    }
                    catch (InterruptedException e)
                    {
                        Thread.currentThread().interrupt();
                    }

                    duration = (System.currentTimeMillis() - start);
                } while (duration < max_duration &&
                        server.queryNames(objectNameQuery, null).size() > 0);

                // Use below to get more accurate metrics.
                String message = "TrustStoreManager TrustStore Stop: took " + duration + "milliseconds";
                logger.information(message);

                mbeanServer.invoke(objectName, "start", null, null);

                break;
            }
        }
    } 
    catch (Exception exception) 
    {
        // Log and throw exception
            throw exception
    }
}

Solution 2:

I don't believe there is a way to do it automatically although your background process could restart tomcat automatically. The keystore only gets read once when the jvm is initialized. There might be a solution if you were to write your own handler that periodically re-checks the keystore but I personally haven't found any examples of this on the Internet.

---

Solution 3:

There is now a way to do this starting with tomcat v8.5.24.

They introduced 2 methods named:

1. reloadSslHostConfig(String hostName) - to reload a specific host
2. reloadSslHostConfigs() - reload all

They can be called in various ways:

1. Using jmx
2. Using manager service (in tomcat v9.x.x)
3. By making custom protocol - I found this way during my research

Details of way 1 and way 2 are easily available in tomcat docs.

Details of how to go about using way 3:

1. Make a class extending the protocol of your choice for eg. Http11NioProtocol
2. Override the required methods and just call super in them to keep default behavior
3. Make a thread in this class to call reloadSslHostConfigs method time to time
4. Package this class in a jar and put that jar in tomcat's lib folder
5. Edit protocol in connector in server.xml to use this custom defined protocol

Find sample code below:

Main protocol class:

package com.myown.connector;

import java.io.File;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.net.URL;
import java.net.URLConnection;
import java.nio.file.StandardCopyOption;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentMap;

import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.net.ssl.SSLSessionContext;

import org.apache.coyote.http11.Http11NioProtocol;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.modeler.Registry;
import org.apache.tomcat.util.net.AbstractEndpoint;
import org.apache.tomcat.util.net.AbstractJsseEndpoint;
import org.apache.tomcat.util.net.GetSslConfig;
import org.apache.tomcat.util.net.SSLContext;
import org.apache.tomcat.util.net.SSLHostConfig;
import org.apache.tomcat.util.net.SSLHostConfigCertificate;
import org.apache.tomcat.util.net.SSLImplementation;
import org.apache.tomcat.util.net.SSLUtil;

public class ReloadProtocol extends Http11NioProtocol {

    private static final Log log = LogFactory.getLog(Http12ProtocolSSL.class);

    public ReloadProtocol() {
        super();
        RefreshSslConfigThread refresher = new 
              RefreshSslConfigThread(this.getEndpoint(), this);
        refresher.start();
    }

    @Override
    public void setKeystorePass(String s) {
        super.setKeystorePass(s);
    }

    @Override
    public void setKeyPass(String s) {
        super.setKeyPass(s);
    }

    @Override
    public void setTruststorePass(String p) {
        super.setTruststorePass(p);
    }

    class RefreshSslConfigThread extends Thread {

        AbstractJsseEndpoint<?> abstractJsseEndpoint = null;
        Http11NioProtocol protocol = null;

        public RefreshSslConfigThread(AbstractJsseEndpoint<?> abstractJsseEndpoint, Http11NioProtocol protocol) {
            this.abstractJsseEndpoint = abstractJsseEndpoint;
            this.protocol = protocol;
        }

        public void run() {
            int timeBetweenRefreshesInt = 1000000; // time in milli-seconds
            while (true) {
                try {
                        abstractJsseEndpoint.reloadSslHostConfigs();
                        System.out.println("Config Updated");
                } catch (Exception e) {
                    System.out.println("Problem while reloading.");
                }
                try {
                    Thread.sleep(timeBetweenRefreshesInt);
                } catch (InterruptedException e) {
                    System.out.println("Error while sleeping");
                }
            }
        }
   }
}

Connector in server.xml should mention this as the protocol:

<Connector protocol="com.myown.connector.ReloadProtocol"
 ..........

Hope this helps.