Parameterize your Configuration

GoCD allows you to parameterize your pipelines and pipeline templates. This powerful feature can help reduce repetition within your configurations and also allows for complex setups using a combination of parameters and pipeline templates.

Using Web Interface

Edit the Parameters tab when defining a pipeline .

Defining and using a parameter

Parameter values are defined in the <params> tag within a pipeline and can be used anywhere within that pipeline using #{param_name}. The following example defines a new parameter called “myParam” and uses it in a job.

<pipeline name="my_pipeline">
  <params>
    <param name="myParam">hello world</param>
  </params>
  <stage name="my_stage">
    <jobs>
      <job name="my_job">
        <tasks>
          <exec command="echo" args="#{myParam}"/>
        </tasks>
      </job>
    </jobs>
  </stage>
</pipeline>

NOTE: If you want to use the # literal, you can escape it using another # literal. For example, if the parameter “foo” has the value “one”, then:

Using parameters in pipeline templates

Parameter usage within templates is similar to usage within pipelines. The only difference is that you cannot define parameters in a template.

<pipeline name="trunk" template="my_template">
  <params>
    <param name="WORKING_DIR">trunk</param>
  </params>
  ...
</pipeline>
<pipeline name="branch" template="my_template">
  <params>
    <param name="WORKING_DIR">branch</param>
  </params>
  ...
</pipeline>

The parameter defined above is used the template below.

<pipeline name="my_template">
  <stage name="my_stage">
    <jobs>
      <job name="my_job">
        <tasks>
          <exec command="echo" args="Updating code from svn repository svn://codebase/#{WORKING_DIR}"/>
        </tasks>
      </job>
    </jobs>
  </stage>
</pipeline>

Rules around usage of parameters

While parameters are generally very flexible, there are some restrictions.

You cannot use a parameter to define:

• Pipeline name
• Stage name
• Job name
• A Job’s property name
• The <runif> configuration for a job’s task
• Another parameter (i.e. you cannot define a parameter using another parameter)
• Pipeline template name
• Material name
• Material passwords (however, for Git and Mercurial, passwords are not captured as separate attribute, hence can be parameterized)
• Trigger-type for Stage

Other restrictions:

• Parameters can currently only be defined within a pipeline.
• A parameter cannot be composed with another parameter i.e. #{foo#{bar}} will not be evaluated recursively.
• If a parameter is referenced but is not defined, then the configuration is invalid (Go will not let you save an invalid configuration).