Скачать или смотреть How to Set a String Input Default Value When Input is Null in Jenkins Pipeline

Learn how to configure default values for string input in Jenkins Pipeline when the input is null. This simple guide offers a step-by-step solution to streamline your Kubernetes deployments.
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This video is based on the question https://stackoverflow.com/q/63822306/ asked by the user 'Dolphin' ( https://stackoverflow.com/u/2628868/ ) and on the answer https://stackoverflow.com/a/63824860/ provided by the user 'Daniel Taub' ( https://stackoverflow.com/u/1706545/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Handling Null Input Values in Jenkins Pipeline Parameters

Working with Jenkins to automate your deployment processes is a fantastic way to ensure efficiency. However, if you're a newbie in Groovy and Jenkins, you might encounter some challenges, especially when dealing with parameter inputs. One common question is: How can I set a default value for a string input when that input is null?

In this post, we’ll go through a straightforward solution for this problem, aimed specifically at Jenkins Pipelines involving Kubernetes resource types.

The Challenge

When you are defining a string parameter in a Jenkins Pipeline, you may want to assign a default value that will be used when the desired input is not provided (i.e., it’s null). For instance, you're setting a Kubernetes resource type, and while most applications default to Deployment, some might be StatefulSet.

Here's the original Groovy code snippet you might be working with:

[[See Video to Reveal this Text or Code Snippet]]

In this setup, if map.k8sResourceType returns null, you’d need to have a default value like Deployment automatically assigned.

The Solution

To achieve the desired functionality, you can utilize an environment block rather than relying purely on parameters. This method allows you to evaluate the input and set a default value effectively.

Step-by-Step Guide

Define your Pipeline: Start by defining the pipeline using the environment feature.

Add Logic for Default Value: Implement a function that checks if the input is null and returns either Deployment or the provided value.

Utilize the Environment Variable: Use the environment variable in your stages for actions like echoing the value.

Here’s how you can implement this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Environment Block: By declaring k8sResourceType in the environment section, you set a scoped variable for the entire pipeline.

GetResourceType Function: This utility function checks if the passed value is null. If it is null, it returns the string Deployment; otherwise, it returns the actual input.

Echo Statement: In the stages section, the echo command will print the currently assigned value of k8sResourceType, showcasing what the default value is if necessary.

Conclusion

By following this guide, you can effectively manage default values for string inputs in Jenkins Pipelines. This not only simplifies your deployment process but ensures that your applications adhere to the most common Kubernetes practices. Remember, this approach will save you time and reduce errors in your automation scripts.

Embrace these enhancements in your Jenkins workflow, and if you run into any questions, feel free to ask within the community!