Blue-green deployment pattern in Jenkins - Step-by-Step Execution

Process Flow - Blue-green deployment pattern

Start with Blue environment live

↓

Deploy new version to Green environment

↓

Test Green environment

↓

Switch traffic to Green

↓

Green is live

↓

Old Blue environment idle

This flow shows how traffic switches between two identical environments (Blue and Green) to deploy updates safely.

Execution Sample

Jenkins

pipeline {
  stages {
    stage('Deploy Green') {
      steps {
        echo 'Deploying to Green environment'
      }
    }
    stage('Switch Traffic') {
      steps {
        echo 'Switching traffic to Green'
      }
    }
  }
}

A Jenkins pipeline that deploys to the Green environment and then switches traffic to it.

Process Table

Step	Action	Environment State	Traffic Routing	Result
1	Start with Blue live	Blue: live, Green: idle	Traffic -> Blue	System serving users from Blue
2	Deploy new version to Green	Blue: live, Green: deploying	Traffic -> Blue	Green environment updated, Blue still live
3	Test Green environment	Blue: live, Green: ready	Traffic -> Blue	Green passes tests, ready for switch
4	Switch traffic to Green	Blue: live, Green: live	Traffic -> Green	Users now served by Green
5	Blue environment idle	Blue: idle, Green: live	Traffic -> Green	Blue environment ready for next update

💡 Traffic switched to Green, Blue environment is idle, deployment complete

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
Blue environment state	live	live	live	idle	idle
Green environment state	idle	deploying	ready	live	live
Traffic routing	Blue	Blue	Blue	Green	Green

Key Moments - 3 Insights

Why do we keep Blue environment live while deploying to Green?

Because Blue serves users without interruption during Green deployment, ensuring no downtime (see execution_table step 2).

What happens if Green environment tests fail?

Traffic stays on Blue, and Green deployment is rolled back or fixed before switching (implied by execution_table step 3 branching).

Why is Blue environment kept idle after switching traffic?

To have a ready fallback environment for quick rollback if needed (execution_table step 5).

Visual Quiz - 3 Questions

Look at the execution_table, at which step does traffic switch from Blue to Green?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Check the 'Traffic Routing' column in execution_table rows

According to variable_tracker, what is the state of the Blue environment after step 4?

A live

B idle

C deploying

D ready

💡 Hint

Look at 'Blue environment state' column after 'After Step 4' in variable_tracker

If the Green environment fails testing, what would happen to traffic routing?

A Switch to Green anyway

B Traffic stops completely

C Traffic remains on Blue

D Traffic switches to a new environment

💡 Hint

Refer to key_moments about test failure and execution_table step 3

Concept Snapshot

Blue-green deployment uses two identical environments: Blue (live) and Green (idle).
Deploy updates to Green while Blue serves users.
Test Green, then switch traffic to Green if tests pass.
Blue becomes idle, ready for rollback.
This ensures zero downtime and quick recovery.

Full Transcript

Blue-green deployment pattern uses two environments to avoid downtime. Initially, Blue is live serving users. The new version is deployed to Green while Blue remains live. After deployment, Green is tested. If tests pass, traffic switches to Green, making it live. Blue then becomes idle, ready for the next update or rollback. This method ensures users experience no downtime and allows quick fallback if needed.