Templates

Converting tomcat.conf into a template

We always start with the original file (e.g. https://gist.github.com/initcron/01f8554fba3305a1bceee9df5ff0aa24)

Create file structure to store the templates

  • Create a director modules/manifests/templates
  • Create a ERB file for tomcat.conf at modules/manifests/templates/tomcat.conf.erb
  • Copy over the contents of the original tomcat.conf. You could use the link above as a sample content

What could go wrong ?

  • You may have named templates directory as template Note the singular vs plural. It should be plural, with s.
  • There is also a possibility that you have a typo in the name.
  • You may have created templates directory at a wrong path. It MUST be at ...modules/tomcat/templates

Now lets start converting the file into a template. How do we do that? * Keep the property names intact. e.g. JAVA_HOME or TOMCAT_USER * Start replacing the values, with template variables. This is where ERB tags are handy. e.g.

Original content such as this

TOMCAT_USER="tomcat"                                                                                                            
SHUTDOWN_WAIT="30"

becomes

TOMCAT_USER="<%= @user >"                                                                                                            
SHUTDOWN_WAIT="<%= @shutdown_wait >"
  • The template variables which start with @var need to be defined as well. Do that in tomcat::params. We already have user defined, lets define the shutdown_wait. What value do we define here? Well params.pp contains the sane default. So whatever came with the package/configs, and was present in tomcat.conf by default is what we use. e.g. 
  $shutdown_wait = 30

TIP : Its always useful to define the params first in params.pp before replacing the values in the template with ERB tags. That way, you would not have to go figure what were the default values, as once replaces, those values are gone. Its also easir to just copy over the params back as template variables.

Exercise

Update the following properties in tomcat.conf in the template, and define the defaults in params.pp

  • TOMCAT_CFG_LOADED
  • JAVA_HOME
  • xms
  • xmx
  • maxpermsize
  • CATALINA_BASE
  • JASPER_HOME
  • CATALINA_TMPDIR
  • SECURITY_MANAGER
  • SHUTDOWN_VERBOSE
  • CATALINA_PID

References :

  • tomcat.conf.erb : https://gist.github.com/initcron/71e939a22e018dbc27dd4ae7deb3a55e
  • tomcat::params : https://gist.github.com/initcron/b08de87a1e835852ac00772252a71a97

Calling templates from config class

Creating templates and params does not have an effect on the system unless you start generating the configs using templates. Currently we are using a file resource to generate this file. Lets convert that to using a template.

In tomcat::config class, update property of the file resource from

source    => 'puppet:///modules/tomcat/tomcat.conf',

to

content  => template('tomcat/tomcat.conf.erb'),

Here is the code after making that change for your reference https://gist.github.com/initcron/87d99703590825716bed515f7e8bf64f