Tomcat Configuration through Environment Variables

uPortal supports loading external properties files to facilitate configuration differences between dev, test, production, etc. This allows a single Docker image or Tomcat zip to be used in all environments / clusters.

Sometimes Tomcat configuration also needs to vary between environments. Examples are port numbers, SSL values, and load balancer IPs.

In the following examples, we will make the HTTP port an external variable.

Update setenv.sh/setenv.bat to Load Config File

First step is to update the setenv files to load the external configuration file we will define, if it exists.

The configuration file name is arbitrary, but we will likely use this name in the future as support is included in uPortal-start.

setenv.sh Changes

After portal.home is defined, include catalina-opts.sh:

CATALINA_OPTS="$CATALINA_OPTS -Dportal.home=$PORTAL_HOME"

# Source catalina.opts if it exists
[ -f "$PORTAL_HOME/catalina.opts" ] && . "$PORTAL_HOME/catalina.opts"

setenv.bat Changes

After portal.home is defined, include catalina-opts.bat:

:gotPortalHome
set CATALINA_OPTS=%CATALINA_OPTS% -Dportal.home=%PORTAL_HOME%

if EXIST "%PORTAL_HOME%\catalina-opts.bat" call "%PORTAL_HOME%\catalina-opts.bat"

With these changes, an external script will be run from the PORTAL_HOME directory. We leverage this to add variables to CATALINA_OPTS with -D.

Populate catalina-opts Files

Next, we add variables to the external file that will be used in Tomcat configuration files. In our example, we will define http.port.

$PORTAL_HOME/catalina-opts.sh

CATALINA_OPTS="$CATALINA_OPTS -Dhttp.port=8081"

%PORTAL_HOME%\catalina-opts.bat

set CATALINA_OPTS="%CATALINA_OPTS% -Dhttp.port=8081"

Use Variable in Tomcat Configuration

Variables defined in CATALINA_OPTS with -D are now available in the Tomcat configuration files. The notation is to use ${ + variable + }.

Example Setting HTTP Port Number

Continuing with our examples, we can now set the HTTP port in conf/server.xml:

    <Connector port="${http.port}" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"
               maxThreads="1200"
               compression="on" 
               compressionMinSize="1024" 
               compressibleMimeType="text/html,text/xml,text/plain,text/css,text/javascript,application/javascript,application/json"
    />

Conclusion

With this approach, there is still the issue of how to handle variables that are expected in the external file but are missing. One approach is to add defaults similar to how PORTAL_HOME is handled in the setenv files. Another approach is to leave out defaults and have the system fail until they are added.