This post will walk you through deploying your application as a WAR file on Apache Tomcat 6 using the Apache HTTP Server as proxy complete with virtual hosting and static file serving. The chosen operating system is Ubuntu, keep this in mind if your system differs. Debian / Ubuntu might have some different locations / tools for managing Apache and Tomcat.
Step 1, creating a WAR file
To create the WAR file we will use Leiningen and the leiningen-war plugin. Open your project.clj file and add the following; uk.org.alienscience/leiningen-war "0.0.3" to; :dev-dependencies. My project.clj looks like:
(defproject myapp "1.0.0-SNAPSHOT" ;; Removed some lines for clarity :dev-dependencies [[swank-clojure "1.2.0"] [uk.org.alienscience/leiningen-war "0.0.3"]] ;; The rest of your config :namespaces [myapp.servlet])
Please lookup the most recent available version on Clojars before copying the code.
This plugin will create a WAR file when we run: lein uberwar. Before we can do this we need to create a servlet class. Add a file called servlet.clj to your project in src/myapp/servlet.clj (change myapp as needed).
Within this file add the following lines:
(ns myapp.servlet (:gen-class :extends javax.servlet.http.HttpServlet) (:require [compojure.route :as route]) (:use ring.util.servlet [myapp.core :only [application]])) (defservice application)
In this case "application" should be the name you chose in core.clj for your defroutes. If you want to have Ring middle-ware as well either wrap it here or create a "def" which you can reference instead.
Now you can compile the servlet class with: lein compile. Before the WAR file can be created a web.xml file also needs to be setup. Create a file called src/web.xml with the following contents.
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<display-name>My App</display-name>
<servlet>
<servlet-name>myapp</servlet-name>
<servlet-class>myapp.servlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myapp</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
</web-app>
Create the WAR with: lein uberwar. Using uberwar makes sure all your dependencies are included.
Step 2, getting the packages
I will be assuming you already have a working Java installation. Enter the following command line to install the dependencies:
sudo apt-get install tomcat6 apache2
Step 3, configure Tomcat
Since I want my application to be available at mydomain.example.com I need to setup Tomcat for virtual hosting. To do this open /etc/tomcat6/server.xml. Search for the <host name=".. and add one below like:
<Host name=" com="" appbase="myapp"> unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false">
You will also need to enable the connector for the AJP protocol. This will be used for interaction between Tomcat and Apache. To do this uncomment the line which says; <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
Your web-application needs to be placed in a new directory within the Tomcat installation (as defined with "appBase"). Create this directory with the following commands:
sudo mkdir /var/lib/tomcat6/myapp sudo chown tomcat6:tomcat6 /var/lib/tomcat6/myapp
Step 4, configuring Apache
Apache has a module specifically designed for proxy-ing traffic to Tomcat. To enable this module run: sudo a2enmod proxy_ajp. Now we can create a virtual host configuration file.
Using your editor of choice open: /etc/apache2/site-available/myapp.example.com. Paste in something like:
<VirtualHost *:80> ServerName myapp.example.com ErrorLog /var/log/apache2/myapp.error.log CustomLog /var/log/apache2/myapp.log combined Alias /static/ "/var/myapp/static/" <Directory /var/myapp/static/> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny Allow from all </Directory> <Proxy *> AddDefaultCharset Off Order deny,allow Allow from all </Proxy> ProxyPass /static ! ProxyPass / ajp://localhost:8009/ ProxyPassReverse / ajp://localhost:8009/ </VirtualHost>
The /var/myapp/static directory will contain the applications static files. You can put this anywhere you want as long as it's readable for Apache.
Now enable the virtual host with: sudo a2ensite myapp.example.com.
Step 5, install application and load
All we have to do now is to install the WAR file. Copy or move the WAR file created in step 1 to /var/lib/tomcat6/myapp/ROOT.war. Make sure it's name will be ROOT.war. This tells Tomcat to use it to "mount" you application on /. Otherwise it will mount it on /name-of-warfile.
The last step is to restart all Tomcat and Apache:
sudo /etc/init.d/tomcat6 restart sudo /etc/init.d/apache2 restart
If everything went well you should now be able to visit myapp.example.com to see your application. To diagnose any problems look in the files specified in /var/log/tomcat6/catalina.out and the ones specified in your Apache virtual host.
