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Setting up Tomcat in some cases can be pain in the ass, especially when your application is pretty complex, in terms of large number of upstream servers which you all want to proxy via SSL.

In my case, I was playing around with Shindig — an OpenSocial container, which itself is a Java servlet delivered via Apache Tomcat server.

The goal was to reverse proxy Shindig through SSL, i.e. it should be able to access it via

https://localhost/gadgets/

with localhost being served by Nginx.

daemon off;

worker_processes  2;
error_log /var/log/nginx_error.log info;
user bananos staff;

events {
    worker_connections  1024;
}

http {
    include /opt/nginx/conf/mime.types;
    default_type application/octet-stream;

    log_format main '$remote_addr - $remote_user [$time_local] "$request" $status $bytes_sent "$http_referer" "$http_user_agent" "$gzip_ratio"';
    ignore_invalid_headers on;
    index index.html;
    client_header_timeout 240;
    client_body_timeout 240;
    send_timeout 240;
    client_max_body_size 100m;
    proxy_buffer_size 128k;
    proxy_buffers 8 128k;

    upstream tomcat_server {
 # Tomcat is listening on default 8080 port
        server 127.0.0.1:8080 fail_timeout=0;
    }

    server {
        server_name localhost;
        listen 443;

        ssl on;
        ssl_session_timeout 5m;
        ssl_protocols SSLv2 SSLv3 TLSv1;
        #make sure you already have this certificate pair!
 ssl_certificate /var/certs/server.crt;
        ssl_certificate_key /var/certs/server.key;
        ssl_session_cache shared:SSL:10m;

 # www-root, we're serving static files from here, accessible via https://localhost/
        location / {
            root  /var/www;
            index index.html index.htm;
        }

 # Our endpoint for tomcat reverse-proxy, assuming your endpoint java-servlet knows
 # how to handle http://localhost/gadgets  requests
        location /gadgets {
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $http_host;
     proxy_set_header X-Forwarded-Proto https;
            proxy_redirect off;
            proxy_connect_timeout      240;
            proxy_send_timeout         240;
            proxy_read_timeout         240;
            # note, there is not SSL here! plain HTTP is used
    proxy_pass http://tomcat_server;
        }
     }
}

And here the magic begins, the main point to not miss here is

Here is a sample Tomcat config which is usually found at

{$CATALINA_HOME}/conf/server.xml


<?xml version='1.0' encoding='utf-8'?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
 -->
<Server port="8005" shutdown="SHUTDOWN">
  <!-- Security listener. Documentation at /docs/config/listeners.html
  <Listener className="org.apache.catalina.security.SecurityListener" />
  -->
  <!--APR library loader. Documentation at /docs/apr.html -->
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->
  <Listener className="org.apache.catalina.core.JasperListener" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <!-- Global JNDI resources
       Documentation at /docs/jndi-resources-howto.html
  -->

<!--  <GlobalNamingResources>-->
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
<!--
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources> -->

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" Note:  A "Service" is not itself a "Container",
       so you may not define subcomponents such as "Valves" at this level.
       Documentation at /docs/config/service.html
   -->
  <Service name="Catalina">

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->
    <!--
    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>
    -->

    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned. Documentation at :
         Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
         Java AJP  Connector: /docs/config/ajp.html
         APR (HTTP/AJP) Connector: /docs/apr.html
         Define a non-SSL HTTP/1.1 Connector on port 8080
    -->
    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"
        proxyName="localhost"
               proxyPort="443"
                />
    <!-- A "Connector" using the shared thread pool-->
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    -->
    <!-- Define a SSL HTTP/1.1 Connector on port 8443
         This connector uses the JSSE configuration, when using APR, the
         connector should be using the OpenSSL style configuration
         described in the APR documentation -->
    <!--
    <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
               maxThreads="150" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" />
    -->

    <!-- Define an AJP 1.3 Connector on port 8009 -->
  <!--  <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />-->

    <!-- An Engine represents the entry point (within Catalina) that processes
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes them
         on to the appropriate Host (virtual host).
         Documentation at /docs/config/engine.html -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    -->
    <Engine name="Catalina" defaultHost="localhost">

      <!--For clustering, please take a look at documentation at:
          /docs/cluster-howto.html  (simple how to)
          /docs/config/cluster.html (reference documentation) -->
      <!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      -->        

      <!-- Use the LockOutRealm to prevent attempts to guess user passwords
           via a brute-force attack -->
<!--      <Realm className="org.apache.catalina.realm.LockOutRealm"> -->
        <!-- This Realm uses the UserDatabase configured in the global JNDI
             resources under the key "UserDatabase".  Any edits
             that are performed against this UserDatabase are immediately
             available for use by the Realm.  -->
<!--        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"    resourceName="UserDatabase"/>-->
<!--      </Realm>-->

      <Host name="localhost"  appBase="webapps"   unpackWARs="true" autoDeploy="true">

        <!-- SingleSignOn valve, share authentication between web applications
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html
             Note: The pattern used is equivalent to using pattern="common" -->

        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log." suffix=".txt"
               pattern="%h %l %u %t "%r" %s %b" resolveHosts="false"/>

      </Host>
    </Engine>
  </Service>
</Server>

As it turned out proxyPort property was the key to proxying Tomcat via Nginx.