Jenkins - Using Different Parameters For Different Environment Branches

The Problem

I want to create a Jenkinsfile that will be responsible for building and deploying an open source project. The Jenkinsfile will be committed to the public git repository so anybody can use it. Thus the settings can't be in the actual Jenkinsfile itself. Instead, the settings need to be injected by the Jenkins server at the point of running.

Also, I have "environment branches" (GitLab flow), so I would like Jenkins to automatically use different sets of settings based on which environment branch is being run. E.g. when I push to the "staging" branch, I would like the "host" parameter to be set to whatever the staging server is.

The Solution

Install the "Config File Provider" plugin. In case you need it, there is a tutorial on how to install a plugin

Then click on Config Files.

Click Add a New Config.

Select JSON for the file type.

Give the config file a name, and then fill in the body of the config file with your relevant settings. Notice that the keys master, staging, and production, for the master, staging, and production branches. Within each of those set any number of parameter names, with the appropriate values.

You may wish to use JsonLint to validate your JSON.

Once you submit, you should see your config file there, with its ID.

You can now use it for fetching parameters based on the branch, as shown below:

stage("build") {
    steps {
        configFileProvider([configFile(fileId: 'myConfigFileId', variable: 'settingsFile')]) {
            script {
                def config = readJSON file:"$settingsFile"
                def branchConfig = config."${env.BRANCH_NAME}"

                if (branchConfig) {
                    def host = branchConfig.host
                    echo "The host for the ${env.BRANCH_NAME} branch is: ${host}"
                }
                else {
                    error("Build failed because failed to fetch settings for branch")
                }
            }
        }
    }
}

Don't stick sensitive data/secrets in this file. Instead, use credential binding, and place the reference to the credential ID in this file in order to dynamically use the correct credentials.

References

• Stack Overflow - Looking for a Jenkins plugin to allow per-branch default parameter values