How to override global "environment {}" Jenkins Variables in a stage?

Question

I'm trying to set up an automated Jenkins pipeline for the Development & Staging branches within our Git repository. I have most of the pipeline working. But I do not know how to override globally set environment {} variables depending on the git branch.

This is my Jenkinsfile:

pipeline {
  agent any

  environment {
    dev_mongo_url = credentials('DEV_MONGO_URL')
    stg_mongo_url = credentials('STG_MONGO_URL')
  }

  stages {

    stage('Env Setup') {
      steps {

        script
        {
        if (env.BRANCH_NAME == 'bugfix/*' || env.BRANCH_NAME == 'feature/*' || env.BRANCH_NAME =='development' || env.BRANCH_NAME =='hotfix/*') {
            env.environment = 'development' 
            echo 'Build & deployment to development environment'
            }


        if (env.BRANCH_NAME == 'staging'){
            env.environment = 'staging'
            echo 'Build & deployment to staging environment'
            
        }
  }
}
}   

    stage('Migration') {
      when {
        anyOf {
          branch 'development';
          branch 'feature/*';          
          branch 'staging'
         }
      }
      steps {
        echo "Installing the project NodeJS dependencies..."
        sh 'npm ci'
        echo "Executing the MongoDB migration script & displaying the status..."
        dir('db-migrations') {
          sh 'npm ci'
          sh('npm run migrate --silent -- --mongodb-url=$mongo_url')
          sh 'npm run migrate:status'
        }

      }
    }

    
    
}
    }

Within the above pipeline, I have the Env Setup stage, which assigns the environment type variable (development/staging) depending on the git branch. We have two MongoDB instances - one for development & one for the staging environment. I have defined both of the MongoDB server URL's under the environment {} block. Now, I want to dynamically connect to the dev/staging mongo servers in the Migration stage, depending on the environment type, and apply the migrations. I'm trying to automatically inject $mongo_url value from the dev_mongo_url & stg_mongo_url global variables depending on the environment. I'm stuck, and I have no clue how to achieve it.

Any help?

Answer 1

See the "using environment variables dynamically" section of the official docs. I think this will answer your question. Here is the snippet of example code from those docs:

pipeline {
    agent any 
    environment {
        // Using returnStdout
        CC = """${sh(
                returnStdout: true,
                script: 'echo "clang"'
            )}""" 
        // Using returnStatus
        EXIT_STATUS = """${sh(
                returnStatus: true,
                script: 'exit 1'
            )}"""
    }
    stages {
        stage('Example') {
            environment {
                DEBUG_FLAGS = '-g'
            }
            steps {
                sh 'printenv'
            }
        }
    }
}

So your code might end up looking something like this:

pipeline {
    agent any 
    environment {
        mongo_url = """${
            switch(env.BRANCH_NAME) {
                case 'bugfix/*'
                case 'feature/*'
                case 'development'
                case 'hotfix/*'
                    'YOUR_DEV_MONGO_URL_HERE'
                    break
                case 'staging'
                    'YOUR_STAGING_MONGO_URL_HERE'
                    break
            }"""
    }
}