Starting automatically another tomcat instance when one goes down - apache

Question

I am working on a Spring-MVC application and using Tomcat to deploy
it. I looked up on net how to create a custom maintenance site when
tomcat is down. It involves using Apache2 in the front and relaying
requests to and fro tomcat, and the maintenance site can be put on
Apache2. Seemed like a lot of hassle just for a webpage when tomcat
is down.
For this reasons, I created a small project and deployed it in
another instance of tomcat as ROOT.war.
I would just like to know if there is any way, I can bring the
maintainance tomcat instance online when production is down.
Here is my server.xml of production for viewing :
<Connector port="80" protocol="HTTP/1.1" compression="force" compressionMinSize="1024"
connectionTimeout="20000"
redirectPort="443" URIEncoding="utf-8"
compressableMimeType="text/html,text/xml,text/plain,text/css,text/ javascript,application/x-javascript,application/javascript"/>
<Connector port="443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="200" compression="force"
compressionMinSize="1024" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS"
keystoreFile="my-keystore.jks" keystorePass="password" URIEncoding="utf-8"
compressableMimeType="text/html,text/xml,text/plain,text/css,text/ javascript,application/x-javascript,application/javascript"
/>
<Connector port="8010" protocol="AJP/1.3" redirectPort="443" URIEncoding="utf-8"
compressableMimeType="text/html,text/xml,text/plain,text/css,text/ javascript,application/x-javascript,application/javascript"
/>
Any help would be nice. Thanks a lot.

Answer 1

A good option used in high availability of application but not sure you would need that.
ran 2 tomcat in 2 separate ports always. one is production server and another maintainence server.
install haproxy so all request goes from here to the production server port.
when haproxy verifies that the port is down or the server not responding go to maintainence port tomcat instance.
in this way, the maintainence activity can be done without any issues. and due to some issues the prod server goes down it automatically call maintainence tomcat instance.