Jenkins: Set Default Value of a Parameter as the Value of Different One

Are you tired of manually setting the default value of a parameter in Jenkins every time you run a build? Do you wish there was a way to dynamically set the default value based on the value of another parameter? Well, you’re in luck! In this article, we’ll show you how to do just that using Jenkins parameters.

What are Jenkins Parameters?

Jenkins parameters are a powerful feature that allows you to customize your build process by allowing users to input values for certain variables. These variables can then be used throughout the build process to customize the build. Jenkins provides several types of parameters, including string, boolean, choice, and file parameters.

Why Set Default Values?

Setting default values for Jenkins parameters can save users time and effort by providing a sensible default value for the parameter. This is especially useful when the parameter has a complex value that needs to be set every time the build is run. By setting a default value, you can ensure that the build runs correctly even if the user forgets to input a value.

Setting Default Values Using Jenkins Parameterized Builds

To set a default value for a Jenkins parameter, you’ll need to create a parameterized build. A parameterized build is a build that uses parameters to customize the build process. Here’s how to create a parameterized build:

1. Create a new job in Jenkins by clicking on the “New Item” button.
2. Choose “Freestyle project” as the project type.
3. Give your job a name and description, then click “OK”.
4. In the job configuration page, click on the “This build is parameterized” checkbox.
5. Click on the “Add Parameter” button.
6. Choose the type of parameter you want to add (e.g. string, boolean, choice, etc.).
7. Give the parameter a name and description, then click “Save”.

Setting a Default Value Using a Groovy Script

Now that you have a parameterized build, you can set a default value for the parameter using a Groovy script. Groovy is a scripting language that can be used to customize Jenkins builds. Here’s an example of how to set a default value using a Groovy script:

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <builders>
    <hudson.tasks.Groovy>
      <command>
        // Set the default value of the parameter
        def defaultValue = "${MY_OTHER_PARAMETER}"
        properties['MY_PARAMETER'] = defaultValue
      </command>
    </hudson.tasks.Groovy>
  </builders>
</project>

In this example, the Groovy script sets the default value of the “MY_PARAMETER” parameter to the value of the “MY_OTHER_PARAMETER” parameter. You can replace “MY_PARAMETER” and “MY_OTHER_PARAMETER” with the actual names of your parameters.

Setting a Default Value Using a Jenkins Plugin

Another way to set a default value for a Jenkins parameter is by using a Jenkins plugin. There are several plugins available that provide this functionality, including the “Parameterized Trigger” plugin and the “Dynamic Parameter” plugin. Here’s an example of how to set a default value using the “Parameterized Trigger” plugin:

First, install the “Parameterized Trigger” plugin by going to the Jenkins plugin manager and searching for “Parameterized Trigger”. Once installed, you can configure the plugin by going to the job configuration page and clicking on the “Add post-build action” button.

Choose “Trigger parameterized build” as the post-build action, then click “Add Parameter” and select the parameter you want to set a default value for.

In the “Default Value” field, enter the value you want to set as the default value. You can use a Groovy script to set the default value dynamically, just like in the previous example.

Examples and Use Cases

Here are some examples of when you might want to set a default value for a Jenkins parameter:

• Environment variables: You can set a default value for an environment variable based on the value of another environment variable.
• Artifact uploading: You can set a default value for the artifact upload path based on the value of a parameter.
• Build configurations: You can set a default value for a build configuration parameter based on the value of another parameter.

Example 1: Environment Variables

Let’s say you have two environment variables, “ENV1” and “ENV2”, and you want to set the default value of “ENV2” to the value of “ENV1”. You can do this using a Groovy script:

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <builders>
    <hudson.tasks.Groovy>
      <command>
        // Set the default value of ENV2 to the value of ENV1
        def defaultValue = "${ENV1}"
        env.ENV2 = defaultValue
      </command>
    </hudson.tasks.Groovy>
  </builders>
</project>

Example 2: Artifact Uploading

Let’s say you have a parameter called “ARTIFACT_UPLOAD_PATH” and you want to set the default value to the value of another parameter called “PROJECT_NAME”. You can do this using the “Parameterized Trigger” plugin:

Parameter	Default Value
ARTIFACT_UPLOAD_PATH	${PROJECT_NAME}/artifacts

Conclusion

In this article, we’ve shown you how to set a default value for a Jenkins parameter based on the value of another parameter. We’ve covered two methods for doing this: using a Groovy script and using a Jenkins plugin. We’ve also provided examples of when you might want to set a default value for a Jenkins parameter, including environment variables, artifact uploading, and build configurations.

By setting default values for Jenkins parameters, you can simplify the build process and reduce the amount of manual input required from users. This can save time and effort, and make your build process more efficient and reliable.

We hope you’ve found this article helpful! Let us know if you have any questions or need further assistance.

FAQs

• Q: Can I set a default value for a parameter using a Jenkinsfile?

  A: Yes, you can set a default value for a parameter using a Jenkinsfile. You can use the `parameters` directive to define the parameter and set its default value.

• Q: Can I set a default value for a parameter using a Jenkins plugin?

  A: Yes, you can set a default value for a parameter using a Jenkins plugin. There are several plugins available that provide this functionality, including the “Parameterized Trigger” plugin and the “Dynamic Parameter” plugin.

• Q: Can I use a Groovy script to set a default value for a parameter?

  A: Yes, you can use a Groovy script to set a default value for a parameter. You can use the `def` keyword to define the default value and assign it to the parameter.

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