DM's Templating

The DM’s templating is about generating live documents at runtime.
These documents can be reports, configuration files for other tools, etc.

Originally, it was designed to generate configuration files for Nagios plugins.

Features

Based on template files, the DM can instantiate them with live information and generate files.
Template files must be located in a same directory. A template can be global (applied to all the Roboconf applications) or restricted to a single one (specific template).

Here is the expected file structure of the templates directory.

- /
-- global-template1.tpl
-- global-template2.tpl
-- global-template3.tpl

-- app1/
-- -- template1.tpl
-- -- template2.tpl

-- app5/
-- -- template1.tpl

Global templates are applied to all the applications.
They are located at the root of the templates directory. Specific templates are applied only to a given application. Such templates must be located in a sub-directory whose name is the same than the application’s one.

The output directory will have the following structure.

app1/
-- global-template1
-- global-template2
-- global-template3
-- template1.tpl
-- template2.tpl

app2/
-- global-template1
-- global-template2
-- global-template3

app5/
-- global-template1
-- global-template2
-- global-template3
-- -- template1.tpl

Files generated from global and specific templates are all located in a same directory, each one being associated with an application.

Templates

Templates are based on Mustache and (a Java port of) Handlebars.
These solutions provide logic-less and semantic templating. The overall idea of these templates is to extract information from Roboconf instances by filtering on components and/or installer names. You can then get runtime information like IP addresses, ports, etc.

For those who are familiar with Handlebars, Roboconf provides additional helpers.
In particular, #all and #is-key.

Here are some examples of templates.

Getting all the instances of VM

{{#all VM}}
- {{name}}
{{/all}}

… could output…

- Tomcat VM1
- Tomcat VM2
- Apche VM

Filtering component names with wildcards

{{#all '/Vm/Tom*' }}
- {{path}}
{{/all}}

… could output…

- /Tomcat VM 1/Tomcat
- /Tomcat VM 2/Tomcat
- /Tomcat VM 3/TomcatServer

Selecting several components at once

{{#all 'Vm | MySQL | */Tom*/War' }}
- {{path}}
{{/all}}

… could output…

- /MySqlVm
- /ApacheVm
- /TomcatVm1
- /TomcatVm1/Tomcat/WebApp
- /TomcatVm2
- /TomcatVm2/Tomcat/WebApp

Selecting by installer name

{{#all '*' installer='script' }}
- {{name}}
{{/all}}

… could output…

- Apache
- Tomcat

Getting exported information

{{#all Vm}}
- {{name}}
	{{#each exports}}
{{name}} = {{value}}
	{{/each}}
{{/all}}

… could output…

- MySqlVm
MySqlVm.ip = 192.168.1.29
- ApacheVm
apacheVm.ip = 192.168.1.14
- TomcatVm1
- TomcatVm2

Displaying only deployed VM

{{#all Vm}}
	{{#data}}{{#is-key 'ip.address'}}
{{name}} => {{value}}
	{{/is-key}}{{/data}}
{{/all}}

… could output…

- MySqlVm
MySqlVm.ip = 192.168.1.29
- ApacheVm
apacheVm.ip = 192.168.1.14

Templates can contain comments

{{! This is a comment that will not be present in generated files. }}

Obviously, these templates are quite simple as they mostly generate lists.
But you can generate any structure you want with this. Other examples are available in the sources.

Installation

To install it, create the net.roboconf.dm.templating.configuration file under the DM’s etc directory and update the following content according to your needs.

# The location of the templates.
templates-directory-location =

# The output directory for generated files.
output-directory-location =

# The poll interval to check modifications on template files (in ms).
poll-interval = 1000

Then, open the DM’s interactive mode and type in…

# Here in version 0.8
bundle:install --start mvn:net.roboconf/roboconf-dm-templating/0.8

You should see something like…

A new listener 'DM's templating' is now available in Roboconf's DM.

… in the DM’s logs.