Stash and unstash for passing data in Jenkins - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to stash files named 'build.log'.

Jenkins

stash name: 'logs', includes: '[1]'

Drag options to blanks, or click blank then click option'

A*.txt

Bbuild.log

C*.xml

Doutput.log

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong filename pattern like '*.txt' or '*.xml'.

The includes parameter specifies which files to stash. Here, 'build.log' is the correct file to stash.

2fill in blank

medium

Complete the code to unstash the files named 'logs'.

Jenkins

unstash '[1]'

Drag options to blanks, or click blank then click option'

Aoutput

Bbuild

Clogs

Darchive

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different stash name than the one used in stash.

The unstash command uses the stash name to retrieve files. Here, the stash name is 'logs'.

3fill in blank

hard

Fix the error in the stash command to correctly stash all '.jar' files.

Jenkins

stash name: 'artifacts', includes: '[1]'

Drag options to blanks, or click blank then click option'

A*.tar

Bjar

C*.zip

D*.jar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'jar' without wildcard does not match files.

The includes parameter needs a pattern with a wildcard to match all '.jar' files, so '*.jar' is correct.

4fill in blank

hard

Fill both blanks to stash all '.txt' files and unstash them later.

Jenkins

stash name: '[1]', includes: '*.txt'
...
unstash '[2]'

Drag options to blanks, or click blank then click option'

Atextfiles

Blogs

Dartifacts

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for stash and unstash causes errors.

The stash and unstash names must match. Here, 'textfiles' is used for both to pass '.txt' files correctly.

5fill in blank

hard

Fill all three blanks to stash '.log' files, unstash them, and then archive the logs.

Jenkins

stash name: '[1]', includes: '*.log'
...
unstash '[2]'
archiveArtifacts artifacts: '*.log', fingerprint: true, allowEmptyArchive: [3]

Drag options to blanks, or click blank then click option'

Alogfiles

Cfalse

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatched stash names or setting allowEmptyArchive to false causing errors.

The stash and unstash names must match ('logfiles'). Setting allowEmptyArchive to true avoids errors if no logs exist.

Practice

1. What is the main purpose of stash and unstash in Jenkins pipelines?

easy

A. To temporarily save and later restore files between pipeline stages

B. To permanently store files on the Jenkins master server

C. To delete files after a pipeline stage completes

D. To send notifications when a stage finishes

Solution

1. Step 1: Understand the role of stash

   The stash command saves files temporarily during a pipeline run.

2. Step 2: Understand the role of unstash

   The unstash command restores those saved files in later stages or nodes.

3. Final Answer:

   To temporarily save and later restore files between pipeline stages -> Option A

4. Quick Check:

   stash + unstash = temporary file sharing [OK]

Hint: Remember stash saves, unstash restores files between stages [OK]

Common Mistakes:

• Thinking stash permanently stores files
• Confusing stash with deleting files
• Assuming stash sends notifications

2. Which of the following is the correct syntax to stash files named output.log in a Jenkins pipeline?

easy

A. stash { name: 'logs', files: 'output.log' }

B. stash('logs', 'output.log')

C. stash name = 'logs' include = 'output.log'

D. stash name: 'logs', includes: 'output.log'

Solution

1. Step 1: Recall stash syntax

   The correct stash syntax uses named parameters: stash name: '...', includes: '...'.

2. Step 2: Match options to syntax

   stash name: 'logs', includes: 'output.log' matches the correct syntax exactly.

3. Final Answer:

   stash name: 'logs', includes: 'output.log' -> Option D

4. Quick Check:

   stash uses named params: name and includes [OK]

Hint: Use named parameters: name and includes for stash [OK]

Common Mistakes:

• Using parentheses like a function call
• Using incorrect parameter names like files
• Using assignment (=) instead of colon (:)

3. Given this Jenkins pipeline snippet:

stage('Build') {
  steps {
    sh 'echo Hello > message.txt'
    stash name: 'msg', includes: 'message.txt'
  }
}
stage('Test') {
  steps {
    unstash 'msg'
    sh 'cat message.txt'
  }
}

What will be the output of the cat message.txt command in the Test stage?

medium

A. Hello

B. No such file or directory

C. Empty output

D. Error: stash not found

Solution

1. Step 1: Understand stash saves message.txt

   The Build stage creates message.txt with content 'Hello' and stashes it as 'msg'.

2. Step 2: Unstash restores message.txt in Test stage

   The Test stage unstashes 'msg', restoring message.txt, then runs cat message.txt.

3. Final Answer:

   Hello -> Option A

4. Quick Check:

   unstash restores files, so cat shows 'Hello' [OK]

Hint: Unstash restores files exactly as stashed [OK]

Common Mistakes:

• Assuming unstash does not restore files
• Expecting an error because stages run separately
• Thinking stash deletes files

4. You wrote this Jenkins pipeline snippet:

stage('Build') {
  agent { label 'build' }
  steps {
    sh 'touch file.txt'
    stash name: 'data', includes: 'file.txt'
  }
}
stage('Deploy') {
  agent { label 'deploy' }
  steps {
    unstash 'artifacts'
    sh 'cat file.txt'
  }
}

But the Deploy stage fails with cat: file.txt: No such file or directory. What is the most likely cause?

medium

A. The unstash command is missing in the Deploy stage

B. The file.txt was not created before stashing

C. The stash name used in unstash does not match the stash name

D. The pipeline syntax for stash is incorrect

Solution

1. Step 1: Check stash and unstash names

   The stash is named 'data' but unstash uses 'artifacts', so names do not match.

2. Step 2: Verify file creation and stash syntax

   file.txt is created before stash, unstash command is present, and stash syntax looks correct. Different agents require proper stash/unstash to pass files.

3. Step 3: Identify the cause

   Mismatched names cause unstash to fail silently, so file.txt is not available in Deploy workspace.

4. Final Answer:

   The stash name used in unstash does not match the stash name -> Option C

5. Quick Check:

   stash and unstash names must match exactly [OK]

Hint: Check stash and unstash names match exactly [OK]

Common Mistakes:

• Using different names in stash and unstash
• Forgetting to create the file before stash
• Omitting unstash command in later stage

5. You want to pass multiple files from a Build stage to a Test stage in Jenkins. Which is the best way to stash and unstash these files?

hard

A. stash name: 'allFiles', includes: '*.log, *.txt'
...
unstash 'allFiles'

B. stash name: 'allFiles', includes: '**/*.log, **/*.txt'
...
unstash 'allFiles'

C. stash name: 'allFiles', includes: '**/*.log **/*.txt'
...
unstash 'allFiles'

D. stash name: 'allFiles', includes: '*.log *.txt'
...
unstash 'allFiles'

Solution

1. Step 1: Understand includes pattern syntax

   Jenkins stash supports comma-separated glob patterns with '**/' for recursive matching.

2. Step 2: Compare options

   stash name: 'allFiles', includes: '**/*.log, **/*.txt' ... unstash 'allFiles' uses comma-separated recursive globs, which is correct. Options A, B, and C either lack recursion (A, B) or use spaces instead of commas (B, C). For example, '**/*.log **/*.txt' misses comma separator.

3. Final Answer:

   stash name: 'allFiles', includes: '**/*.log, **/*.txt' ... unstash 'allFiles' -> Option B

4. Quick Check:

   Use comma-separated globs with '**/' for multiple file types [OK]

Hint: Use comma-separated globs with '**/' for multiple files [OK]

Common Mistakes:

• Using spaces instead of commas to separate globs
• Missing recursive '**/' causing files to be skipped
• Incorrect glob syntax causing no files to stash