Pipeline triggers and upstream/downstream in Jenkins - Step-by-Step Execution

Process Flow - Pipeline triggers and upstream/downstream

Upstream Job completes

↓

Trigger Downstream Job

↓

Downstream Job starts

↓

Downstream Job completes

↓

Pipeline chain ends

This flow shows how one Jenkins job (upstream) triggers another job (downstream) after it finishes, creating a chain of jobs.

Execution Sample

Jenkins

pipeline {
  agent any
  stages {
    stage('Build') {
      steps { echo 'Building...' }
    }
  }
  post {
    success { build job: 'DownstreamJob' }
  }
}

A Jenkins pipeline that runs a build stage and triggers a downstream job when successful.

Process Table

Step	Event	Action	Job State	Triggered Job
1	Start Upstream Job	Begin pipeline execution	Upstream: Running	None
2	Build Stage	Execute build steps	Upstream: Running	None
3	Build Success	Post success block triggers	Upstream: Success	DownstreamJob triggered
4	Downstream Job Start	Downstream job begins	Downstream: Running	None
5	Downstream Job Complete	Downstream job finishes	Downstream: Success	None
6	Pipeline Chain End	All jobs completed	All: Success	None

💡 Downstream job completes successfully, ending the pipeline chain.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
Upstream Job State	Not started	Running	Success	Success	Success
Downstream Job State	Not started	Not started	Triggered	Success	Success

Key Moments - 2 Insights

Why does the downstream job only start after the upstream job succeeds?

Because the trigger is inside the 'post { success { ... } }' block, it runs only when the upstream job finishes successfully, as shown in execution_table row 3.

Can the downstream job start if the upstream job fails?

No, the downstream job trigger is inside the success block, so it won't run if the upstream job fails. This is clear from the absence of triggering in failure scenarios.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the downstream job start running?

A Step 3

B Step 4

C Step 2

D Step 5

💡 Hint

Check the 'Job State' and 'Event' columns in execution_table row 4.

According to variable_tracker, what is the state of the downstream job after step 3?

A Triggered

B Not started

C Running

D Success

💡 Hint

Look at the 'Downstream Job State' row under 'After Step 3' in variable_tracker.

If the upstream job fails, what happens to the downstream job trigger in this pipeline?

A Downstream job triggers anyway

B Downstream job triggers only if manually started

C Downstream job does not trigger

D Pipeline retries upstream job automatically

💡 Hint

Refer to key_moments explanation about the 'post { success { ... } }' block.

Concept Snapshot

Jenkins pipelines can trigger downstream jobs after upstream jobs finish.
Use 'post { success { build job: "JobName" } }' to trigger only on success.
Upstream job runs first, then downstream job starts automatically.
This creates a chain of jobs for complex workflows.

Full Transcript

This visual execution shows how Jenkins pipelines trigger downstream jobs after upstream jobs complete successfully. The upstream job runs its stages, then in the post success block, it triggers the downstream job. The downstream job starts only after the upstream job finishes successfully, creating a chain of jobs. Variables track job states changing from not started to running to success. Key moments clarify that downstream jobs do not trigger if the upstream job fails. The quiz tests understanding of when downstream jobs start and how triggers depend on upstream job results.