When building a real application you often find yourself having to deal with different stages of the software. The most common stages are development, testing and production, but you can have many more. This means that you need a different environment to deploy the application on each of the current stages. You use different environments to be able to perform versioning, different configurations, test bug fixes and so on. This also poses challenges on upgrading environments, changing shared configuration or keeping track of the servers. I will show you how to do it with Tomcat.
The easiest way to set up multiple Tomcat instances is to duplicate the entire Tomcatfolder and change a few configurations. I don’t advise doing it this way, since it’s harder to maintain, harder to spin up new instances and harder to upgrade. Instead, we will set up the instances in a much more flexible way, by duplicating only a few things and keeping a shared base folder for all instances.
I’ve used version 7.0, but this should also work with other versions. I’m also doing the setup in a Unix like environment. This can also be accomplished in a Windows box, but the commands need to be adjusted.
Unzip the installation folder to a directory of your choice. I just recommend to do it in a parent folder and you can use a name like
Now, instead of using the unzipped folder, we are going to create a link to it, like this:
ln -s apache-tomcat-7.0.64/ current
Here is a sample:
radcortez:tomcat radcortez$ pwd /usr/local/share/java/tomcat radcortez:tomcat radcortez$ ln -s apache-tomcat-7.0.64/ current radcortez:tomcat radcortez$ ls total 8 drwxr-xr-x 4 radcortez admin 136B Sep 24 01:49 . drwxr-xr-x@ 26 radcortez admin 884B Sep 24 01:38 .. drwxr-xr-x 13 radcortez admin 442B Sep 24 01:45 apache-tomcat-7.0.64 lrwxr-xr-x 1 radcortez admin 21B Sep 24 01:49 current -> apache-tomcat-7.0.64/ radcortez:tomcat radcortez$
To keep this simple, we are going to create two instances:
production. But keep in mind that you can create as many as you want by making the necessary adjustments to the scripts.
Create a folder now named
environments. Inside, create a folder named
radcortez:tomcat radcortez$ mkdir instances radcortez:tomcat radcortez$ cd instances/ radcortez:instances radcortez$ mkdir development radcortez:instances radcortez$ ls total 0 drwxr-xr-x 4 radcortez admin 136B Sep 24 01:56 . drwxr-xr-x 5 radcortez admin 170B Sep 24 01:56 .. drwxr-xr-x 2 radcortez admin 68B Sep 24 01:56 development radcortez:instances radcortez$ pwd /usr/local/share/java/tomcat/instances radcortez:instances radcortez$
Now copy the folders
work from the Tomcat install folder into
radcortez:instances radcortez$ ls total 0 drwxr-xr-x 4 radcortez admin 136B Sep 24 02:06 . drwxr-xr-x 5 radcortez admin 170B Sep 24 01:56 .. drwxr-xr-x 2 radcortez admin 68B Sep 24 02:06 development drwxr-xr-x 2 radcortez admin 68B Sep 24 02:06 production radcortez:instances radcortez$ cp -rf ../current/conf/ development/conf radcortez:instances radcortez$ cp -rf ../current/logs/ development/logs radcortez:instances radcortez$ cp -rf ../current/temp/ development/temp radcortez:instances radcortez$ cp -rf ../current/webapps/ development/webapps radcortez:instances radcortez$ cp -rf ../current/work/ development/work radcortez:instances radcortez$ ls development/ total 0 drwxr-xr-x 7 radcortez admin 238B Sep 24 02:08 . drwxr-xr-x 4 radcortez admin 136B Sep 24 02:06 .. drwxr-xr-x 9 radcortez admin 306B Sep 24 02:07 conf drwxr-xr-x 2 radcortez admin 68B Sep 24 02:07 logs drwxr-xr-x 3 radcortez admin 102B Sep 24 02:08 temp drwxr-xr-x 7 radcortez admin 238B Sep 24 02:08 webapps drwxr-xr-x 2 radcortez admin 68B Sep 24 02:08 work radcortez:instances radcortez$
If you wish, you can now remove these folders from the Tomcat install folder, but is not mandatory.
Home and Base
The idea here is to share the main Tomcat folders and each instance has a copy of their personal folders to not clash with each other. Tomcat defines two environment variables called
CATALINA_BASE that allow us to do that.
bin folder in the instances
development. Add the following
#!/bin/bash TOMCAT_HOME="$(dirname $0)/.." cd $TOMCAT_HOME && TOMCAT_HOME=$PWD && cd - &> /dev/null export TOMCAT_HOME export CATALINA_HOME="$(readlink -f "$TOMCAT_HOME/../../current")" export CATALINA_BASE="$(readlink -f "$TOMCAT_HOME")" export CATALINA_OPTS="-Dhttp.port=8080 $CATALINA_OPTS" export CATALINA_OPTS="-Dhttps.port=8443 $CATALINA_OPTS" export CATALINA_OPTS="-Dajp.port=8009 $CATALINA_OPTS" export CATALINA_OPTS="-Dshutdown.port=8005 $CATALINA_OPTS" echo "JAVA_HOME set to $JAVA_HOME" echo "CATALINA_BASE set to $CATALINA_BASE" echo "CATALINA_HOME set to $CATALINA_HOME" $CATALINA_HOME/bin/"$(basename "$0")" "$@"
Note: If you are using MacOSX, you might need to install
brew and replace
greadlink to achieve the proper behaviour.
This script is going to set up the proper configuration variables to point to our sharedTomcat and the specific instance folders. Note the properties
shutdown.port are included in the
CATALINA_OPTS environment variable. With these we can pass specific configuration to the
server.xml file. Tomcat is smart enough to perform property replace substitution as long as you have the proper placeholders in place.
All these operations are performed in the
development folder instance.
Edit the file
conf/server.xml do the following changes;
Note: Unfortunately the only place where property replacement doesn’t work is the shutdown port. I think this is a bug in Tomcat and should be fixed. So for now, we need to keep it hardcoded.
On the bin folder, create links to
exec.sh to the following files:
radcortez:bin radcortez$ ln -s exec.sh catalina.sh radcortez:bin radcortez$ ln -s exec.sh startup.sh radcortez:bin radcortez$ ln -s exec.sh shutdown.sh radcortez:bin radcortez$ ls total 32 drwxr-xr-x 6 radcortez admin 204B Sep 24 10:14 . drwxr-xr-x 8 radcortez admin 272B Sep 24 08:07 .. lrwxr-xr-x 1 radcortez admin 7B Sep 24 10:13 catalina.sh -> exec.sh -rw-r--r-- 1 radcortez admin 651B Sep 24 09:32 exec.sh lrwxr-xr-x 1 radcortez admin 7B Sep 24 10:14 shutdown.sh -> exec.sh lrwxr-xr-x 1 radcortez admin 7B Sep 24 10:13 startup.sh -> exec.sh radcortez:bin radcortez$
This will allow you to call the original Tomcat, but by calling the
exec.sh set up first. The magic is done by the line
$CATALINA_HOME/bin/"$(basename "$0")" "$@" in the
The instance should be ready to be executed. Just run it as you would do it normally by executing
sh catalina.sh run or
sh startup.sh from the
development instance folder.
Just duplicate the
development instance folder to a
production one and edit the
bin/exec.sh to update it with different ports. You can user 7080 for http, 7443 for https, 7009 for ajp and 7005 for the shutdown.
Since property replacement is not working properly for the shutdown port, we need to manually edit
conf/server.xml from the
production instance and replace 8005 by 7005. When this bug is fixed, and you actually use a property, you don’t have to worry about doing this.
Note: You might need to reestablish the proper links in the scripts
shutdown.sh stored in the
After this, your second instance
production is ready to run. If you need more, just repeat the last steps, making sure to pick ports that don’t conflict with the instances already set up.
With this set up you can now:
- Create new instances easily with minimum changes. You can actually have one untouched unchanged instance, that you can use to copy from to create others.
- Update the Tomcat version, just by installing a new distribution and updating the link to
- If you place jars in the
libsfolder of the
HOMEinstallation, they become instantly available to all instances.
- Instead of duplicating the
conffolder, you can actually link to the one in
HOMEand also share the configuration between all environments. Or just link to the files you want to share.
- Remove an instance, by just deleting its
- Also works for TomEE!
Let me know if this was useful to you or if you had any trouble following the blog instructions!