How to access Tomcat 8 admin gui from different host?

As covered in How To Install Apache Tomcat 8 on Ubuntu 16.04

By default, newer versions of Tomcat restrict access to the Manager and Host Manager apps to connections coming from the server itself. Since we are installing on a remote machine, you will probably want to remove or alter this restriction. To change the IP address restrictions on these, open the appropriate context.xml files.

If you followed that installation tutorial, those file can be found at:

• /opt/tomcat/webapps/manager/META-INF/context.xml

• sudo nano /opt/tomcat/webapps/host-manager/META-INF/context.xml

To allow remote access, edit the files and comment out the part of the configuration file specifying the IP address restriction or replace them with a list of IP addresses that you would like to whitelist.

<Context antiResourceLocking="false" privileged="true" >
  <!--<Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />-->
</Context>

Restart Tomcat for the changes to take effect:

sudo systemctl restart tomcat

Remember, since Apache mod_jk makes a local connection to Tomcat on port 8080 and proxies it to port 443 over HTTPS (or port 80 if you are not setting up SSL), you will access it at https://your_ip_address/manager/html

Heya,

When you’re securing your Tomcat deployment with Apache or Nginx as a reverse proxy, you typically also want to secure access to the management GUIs provided by Tomcat, such as the Manager App and the Host Manager App.

1. Update Tomcat’s context.xml

Tomcat’s Manager and Host Manager apps are by default configured to be accessible only from the localhost. To allow access from remote machines, you have to modify the context.xml files for these apps. Here’s how to do it:

Open the Manager App’s context.xml

sudo nano /var/lib/tomcat8/webapps/manager/META-INF/context.xml

Comment out or Remove the IP Restriction

You’ll find a line similar to the following:

<Valve className="org.apache.catalina.valves.RemoteAddrValve"
allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />

Comment out this line by wrapping it in tags, like so:

<!--
<Valve className="org.apache.catalina.valves.RemoteAddrValve"
allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
-->

Repeat for the Host Manager’s context.xml

sudo nano /var/lib/tomcat8/webapps/host-manager/META-INF/context.xml

Then restart Tomcat

sudo systemctl restart tomcat8

2. Configure Apache to Proxy Requests to Tomcat Manager

Even after updating context.xml, you still can’t access the Tomcat Manager App if port 8080 is closed and only Apache is serving requests. You will need to create a reverse proxy rule for Apache to forward requests to the Manager App.

1. Edit Apache Configuration

sudo nano /etc/apache2/sites-available/your-tomcat-site.conf

2. Add ProxyPass Directives

For the Manager App, add something like this:

<Location /manager>
    ProxyPass ajp://localhost:8009/manager
    ProxyPassReverse ajp://localhost:8009/manager
</Location>

3. Restart Apache

sudo systemctl restart apache2

Now, try accessing the Tomcat Manager by going to:

http://your-domain-or-ip/manager