Stash and unstash for passing data in Jenkins - Step-by-Step Execution

Process Flow - Stash and unstash for passing data

Start Pipeline

↓

Stash files

↓

Move to another stage

↓

Unstash files

↓

Use files in new stage

↓

Pipeline continues or ends

This flow shows how Jenkins saves files with stash, then retrieves them later with unstash to share data between pipeline stages.

Execution Sample

Jenkins

stage('Build') {
  stash name: 'app', includes: '**/*.jar'
}
stage('Test') {
  unstash 'app'
  sh 'java -jar app.jar'
}

This Jenkins pipeline stashes jar files in the Build stage, then unstashes and runs them in the Test stage.

Process Table

Step	Action	Files Affected	Pipeline Stage	Result
1	Start Build stage	none	Build	Build stage begins
2	Stash files named 'app'	*.jar files	Build	Files saved for later stages
3	End Build stage	none	Build	Build stage ends
4	Start Test stage	none	Test	Test stage begins
5	Unstash files named 'app'	*.jar files	Test	Files restored for use
6	Run 'java -jar app.jar'	app.jar	Test	Application runs using unstashed files
7	End Test stage	none	Test	Test stage ends
8	Pipeline ends	none	Pipeline	All stages complete

💡 Pipeline ends after all stages complete and files are passed via stash/unstash

Status Tracker

Variable	Start	After Step 2	After Step 5	Final
Stash 'app'	empty	*.jar files saved	files restored	files used in Test stage

Key Moments - 3 Insights

Why do we need to stash files in one stage and unstash in another?

Because each Jenkins stage runs in a separate workspace, stashing saves files so they can be restored later in a different stage, as shown in steps 2 and 5.

What happens if you try to unstash files that were never stashed?

The pipeline will fail at the unstash step (step 5) because there are no saved files with that stash name, causing an error.

Does unstashing overwrite existing files in the workspace?

Yes, unstashing restores files and can overwrite files with the same name in the current workspace, as seen when files are restored in step 5.

Visual Quiz - 3 Questions

Look at the execution table, what files are saved during the stash step?

A *.jar files

B No files

C *.txt files

D All files

💡 Hint

Check Step 2 in the execution table where stash saves files.

At which step does the pipeline restore the stashed files?

A Step 7

B Step 2

C Step 5

D Step 1

💡 Hint

Look for the unstash action in the execution table.

If the stash name was changed in the unstash step to 'app2', what would happen?

A Files would still be restored

B Pipeline would fail at unstash

C Files would be partially restored

D Pipeline would skip unstash silently

💡 Hint

Refer to key moment about unstashing files that were never stashed.

Concept Snapshot

Jenkins stash saves files in one stage for later use.
Unstash restores those files in another stage.
Use stash name to identify files.
Each stage has separate workspace.
Stash/unstash passes data between stages safely.

Full Transcript

This visual execution shows how Jenkins pipelines use stash and unstash to pass files between stages. First, files matching a pattern are saved with stash in the Build stage. Then, in the Test stage, unstash restores those files so they can be used. Each step is tracked showing when files are saved, restored, and used. Key points include that stash is needed because each stage runs separately, unstash requires the correct stash name, and unstashing overwrites files in the workspace. The quiz tests understanding of when files are saved and restored and what happens if names don't match. This helps beginners see the step-by-step flow of passing data in Jenkins pipelines.