Why Artifact retention policies in Jenkins? - Purpose & Use Cases

The Big Idea

What if your Jenkins server could clean up after itself and never run out of space?

The Scenario

Imagine you run a busy bakery where every day you bake dozens of cakes and store them all in the fridge. Over time, the fridge gets so full that you can't find the fresh cakes easily, and old cakes start to spoil.

In Jenkins, this is like keeping every build artifact forever without cleaning up.

The Problem

Manually deleting old build files is slow and risky. You might delete something important by mistake or forget to clean up, causing your storage to fill up and Jenkins to slow down or crash.

This wastes time and can break your automation pipeline.

The Solution

Artifact retention policies automatically keep only the important build files and delete the rest after a set time or number of builds.

This keeps your storage clean, Jenkins fast, and your builds reliable without manual effort.

Before vs After

✗ Before

Keep all build artifacts forever
Manually delete files when storage is full

✓ After

Set 'Discard old builds' in Jenkins
Define days or number of builds to keep artifacts

What It Enables

Automatically managing build files so your Jenkins server stays clean, fast, and efficient without manual work.

Real Life Example

A software team runs nightly builds and stores test reports and binaries. With artifact retention policies, only the last 10 builds' files are kept, saving disk space and avoiding slowdowns.

Key Takeaways

Manual cleanup of build files is slow and error-prone.

Artifact retention policies automate cleanup based on rules.

This keeps Jenkins storage healthy and builds running smoothly.

Practice

1. What is the main purpose of artifact retention policies in Jenkins?

easy

A. To manage disk space by deleting old build files

B. To speed up the build process by caching dependencies

C. To increase the number of builds stored indefinitely

D. To automatically trigger builds on code changes

Solution

1. Step 1: Understand artifact retention policies

   Artifact retention policies control how long build files are kept to avoid using too much disk space.

2. Step 2: Identify the main goal

   The main goal is to delete old build files to free up disk space.

3. Final Answer:

   To manage disk space by deleting old build files -> Option A

4. Quick Check:

   Artifact retention = disk space management [OK]

Hint: Retention policies delete old builds to save space [OK]

Common Mistakes:

• Confusing retention with build triggering
• Thinking retention speeds up builds
• Assuming retention keeps all builds forever

2. Which Jenkins pipeline syntax correctly sets a retention policy to keep only the last 5 builds?

easy

A. archiveArtifacts(numToKeepStr: '5')

B. buildDiscarder(keepLast: 5)

C. buildDiscarder(logRotator(numToKeepStr: '5'))

D. archiveArtifacts(logRotator(numToKeepStr: '5'))

Solution

1. Step 1: Identify correct syntax for retention

   Retention uses buildDiscarder with logRotator to specify how many builds to keep.

2. Step 2: Check option correctness

   buildDiscarder(logRotator(numToKeepStr: '5')) uses correct syntax: buildDiscarder(logRotator(numToKeepStr: '5')). Others misuse archiveArtifacts or wrong parameters.

3. Final Answer:

   buildDiscarder(logRotator(numToKeepStr: '5')) -> Option C

4. Quick Check:

   Retention uses buildDiscarder + logRotator [OK]

Hint: Retention = buildDiscarder with logRotator [OK]

Common Mistakes:

• Using archiveArtifacts to set retention
• Wrong parameter names like keepLast
• Nesting logRotator inside archiveArtifacts

3. Given this Jenkins pipeline snippet:

pipeline {
  options {
    buildDiscarder(logRotator(numToKeepStr: '3', daysToKeepStr: '7'))
  }
  stages {
    stage('Build') {
      steps {
        echo 'Building...'
      }
    }
  }
}

What happens to builds older than 7 days or beyond the last 3 builds?

medium

A. They are deleted to free disk space

B. They are archived permanently

C. They trigger a new build automatically

D. They are kept indefinitely

Solution

1. Step 1: Understand logRotator parameters

   It keeps only the last 3 builds and deletes builds older than 7 days.

2. Step 2: Determine effect on old builds

   Builds older than 7 days or beyond the last 3 are deleted to save space.

3. Final Answer:

   They are deleted to free disk space -> Option A

4. Quick Check:

   logRotator deletes old builds [OK]

Hint: logRotator deletes builds older than days or count [OK]

Common Mistakes:

• Thinking builds are archived permanently
• Assuming builds trigger new builds
• Believing builds are kept forever

4. You wrote this Jenkins pipeline snippet to keep artifacts for 10 days:

options {
  buildDiscarder(logRotator(artifactDaysToKeep: '10'))
}

But artifacts are not deleted after 10 days. What is the likely problem?

medium

A. logRotator does not support artifact retention

B. The buildDiscarder option must be inside stages

C. You must use archiveArtifacts to delete old artifacts

D. The parameter name should be artifactDaysToKeepStr, not artifactDaysToKeep

Solution

1. Step 1: Check logRotator parameter names

   logRotator parameters for strings end with 'Str', like artifactDaysToKeepStr.

2. Step 2: Identify the syntax issue

   Missing 'Str' means the parameter is not recognized, so default retention applies and artifacts aren't deleted after 10 days.

3. Final Answer:

   The parameter name should be artifactDaysToKeepStr, not artifactDaysToKeep -> Option D

4. Quick Check:

   logRotator params end with 'Str' [OK]

Hint: logRotator params like artifactDaysToKeepStr end with Str [OK]

Common Mistakes:

• Using wrong parameter names
• Expecting logRotator to delete artifacts
• Placing buildDiscarder outside options block

5. You want to keep artifacts only for the last 4 builds and delete older artifacts automatically, while keeping older builds. Which Jenkins pipeline snippet correctly applies this retention policy?

hard

A. steps { archiveArtifacts artifacts: '**/*', onlyIfSuccessful: true, retentionDays: 4 }

B. options { buildDiscarder(logRotator(artifactNumToKeepStr: '4')) }

C. options { buildDiscarder(logRotator(numToKeepStr: '4')) } steps { archiveArtifacts artifacts: '**/*', onlyIfSuccessful: true }

D. steps { archiveArtifacts artifacts: '**/*', keepOnlyLast: 4 }

Solution

1. Step 1: Understand roles for artifact-specific retention

   To keep artifacts from only the last 4 builds while retaining builds, use artifactNumToKeepStr.

2. Step 2: Check option correctness

   options { buildDiscarder(logRotator(artifactNumToKeepStr: '4')) }: buildDiscarder(logRotator(artifactNumToKeepStr: '4')) keeps artifacts from last 4 builds, deletes older artifacts, keeps all builds. C deletes old builds too. B/D use invalid params.

3. Final Answer:

   options { buildDiscarder(logRotator(artifactNumToKeepStr: '4')) } -> Option B

4. Quick Check:

   artifactNumToKeepStr for artifacts only [OK]

Hint: artifactNumToKeepStr keeps artifacts from last N builds [OK]

Common Mistakes:

• Using invalid parameters like retentionDays or keepOnlyLast
• Trying to control retention only via archiveArtifacts
• Misplacing buildDiscarder outside options block