Jenkins versions and LTS - Commands & Configuration

Introduction

Jenkins is a tool that helps automate software building and testing. It has different versions, including Long-Term Support (LTS) versions that are more stable and updated less often. Choosing the right version helps keep your automation reliable and secure.

When you want a stable Jenkins setup that changes less often and is tested thoroughly.

When you need the latest features and improvements Jenkins offers quickly.

When you want to avoid unexpected issues by using a version with long-term support.

When planning upgrades and want to minimize downtime by using LTS versions.

When running production pipelines that require maximum reliability.

Commands

This command shows the current Jenkins version installed on your system to verify which version you are running.

Terminal

jenkins --version

Expected Output

2.387.1

This command fetches the latest Jenkins LTS version number from the official Jenkins update site.

Terminal

curl -s https://updates.jenkins.io/stable/latestCore.txt

Expected Output

2.387.1

This command fetches the latest Jenkins weekly (non-LTS) version number from the official Jenkins update site.

Terminal

curl -s https://updates.jenkins.io/current/latestCore.txt

Expected Output

2.414

This command installs a specific Jenkins LTS version (2.387.1) on a Debian-based system to ensure stability.

Terminal

sudo apt-get install jenkins=2.387.1

Expected Output

Reading package lists... Done

Building dependency tree       

Reading state information... Done

The following NEW packages will be installed:

  jenkins

0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.

Need to get 0 B/100 MB of archives.

After this operation, 500 MB of additional disk space will be used.

Selecting previously unselected package jenkins.

(Reading database ... 123456 files and directories currently installed.)

Preparing to unpack .../jenkins_2.387.1_all.deb ...

Unpacking jenkins (2.387.1) ...

Setting up jenkins (2.387.1) ...

Processing triggers for systemd (245.4-4ubuntu3.13) ...

→

=2.387.1 - Specifies the exact Jenkins version to install

This command checks if the Jenkins service is running after installation.

Terminal

systemctl status jenkins

Expected Output

● jenkins.service - Jenkins Continuous Integration Server

   Loaded: loaded (/lib/systemd/system/jenkins.service; enabled; vendor preset: enabled)

   Active: active (running) since Fri 2024-06-14 10:00:00 UTC; 1min 30s ago

 Main PID: 1234 (java)

    Tasks: 50 (limit: 4915)

   Memory: 300.0M

   CGroup: /system.slice/jenkins.service

           └─1234 /usr/bin/java -jar /usr/share/jenkins/jenkins.war

Key Concept

If you remember nothing else from this pattern, remember: Jenkins LTS versions provide a stable and tested environment ideal for production, while weekly versions offer the latest features but change more often.

Common Mistakes

Installing the latest weekly Jenkins version in a production environment without testing.

Weekly versions may have new features but can introduce bugs or instability.

Use the latest LTS version for production to ensure stability and reliability.

Not checking the installed Jenkins version before upgrading.

Upgrading blindly can cause compatibility issues with existing plugins or pipelines.

Always check the current version with 'jenkins --version' and review release notes before upgrading.

Using generic install commands without specifying the version.

This installs the latest version, which might not be the desired LTS or stable release.

Specify the exact version number during installation to control which Jenkins version is installed.

Summary

Use 'jenkins --version' to check your current Jenkins version.

Fetch the latest LTS or weekly version numbers from Jenkins update URLs to decide which to install.

Install Jenkins with a specific version to ensure stability, especially in production.

Verify Jenkins service is running after installation with 'systemctl status jenkins'.

Practice

1. What is the main difference between Jenkins LTS and weekly versions?

easy

A. LTS versions are more stable and updated less frequently

B. Weekly versions are more stable than LTS versions

C. LTS versions have fewer features than weekly versions

D. Weekly versions are only for testing and cannot be used in production

Solution

1. Step 1: Understand Jenkins version types

   Jenkins offers two main version types: LTS (Long-Term Support) and weekly releases.

2. Step 2: Compare update frequency and stability

   LTS versions are designed to be stable and receive updates less often, while weekly versions get new features and fixes more frequently but may be less stable.

3. Final Answer:

   LTS versions are more stable and updated less frequently -> Option A

4. Quick Check:

   Stability and update frequency = LTS [OK]

Hint: LTS means stable and slow updates, weekly means fast updates [OK]

Common Mistakes:

• Confusing stability between LTS and weekly
• Thinking weekly versions are for production only
• Assuming LTS has fewer features always

2. Which command correctly checks the Jenkins version installed on a Linux server?

easy

A. jenkins --version

B. jenkins version check

C. jenkins -v

D. java -jar jenkins.war --version

Solution

1. Step 1: Identify Jenkins version check command

   Jenkins runs as a Java application using the jenkins.war file, so checking version uses the java command with the war file.

2. Step 2: Validate correct syntax

   The correct syntax is: java -jar jenkins.war --version. Other options are invalid commands or incorrect flags.

3. Final Answer:

   java -jar jenkins.war --version -> Option D

4. Quick Check:

   Use java -jar jenkins.war --version [OK]

Hint: Use java -jar jenkins.war --version to check Jenkins version [OK]

Common Mistakes:

• Using 'jenkins --version' which is invalid
• Trying 'jenkins -v' which Jenkins does not support
• Typing commands without java or war file

3. If you install Jenkins weekly version and then run java -jar jenkins.war --version, what output should you expect?

medium

A. An error saying version cannot be determined

B. A version number with a date indicating the weekly build

C. The latest LTS version number

D. No output, just returns to prompt

Solution

1. Step 1: Understand output of version command

   The command shows the Jenkins version installed, including build info.

2. Step 2: Identify output for weekly version

   Weekly versions include a date or build number in the version string, unlike LTS which is a stable release number.

3. Final Answer:

   A version number with a date indicating the weekly build -> Option B

4. Quick Check:

   Weekly version output includes date/build info [OK]

Hint: Weekly versions show date in version output [OK]

Common Mistakes:

• Expecting LTS version number for weekly install
• Thinking command returns no output
• Assuming error occurs for weekly versions

4. You installed Jenkins LTS but notice frequent plugin compatibility errors. What is the most likely cause?

medium

A. Running Jenkins without Java installed

B. Installing weekly plugins on LTS Jenkins

C. Using an outdated LTS version with newer plugins

D. Incorrect Jenkins home directory permissions

Solution

1. Step 1: Analyze plugin compatibility issue

   Plugin errors often occur when Jenkins core and plugins versions mismatch.

2. Step 2: Identify cause related to LTS version

   Using an older LTS version while installing newer plugins can cause incompatibility.

3. Final Answer:

   Using an outdated LTS version with newer plugins -> Option C

4. Quick Check:

   Old LTS + new plugins = compatibility errors [OK]

Hint: Match plugin versions with Jenkins core version [OK]

Common Mistakes:

• Blaming weekly plugins on LTS without checking versions
• Ignoring Java installation issues
• Assuming permissions cause plugin errors

5. Your team wants a Jenkins version that balances stability and access to new features for a production environment. Which version strategy is best?

hard

A. Use the latest LTS version and update it every 12 weeks

B. Use the latest weekly version and update plugins weekly

C. Use an old LTS version and never update it

D. Use weekly versions but only update every 6 months

Solution

1. Step 1: Understand production needs

   Production environments need stability but also reasonable updates for security and features.

2. Step 2: Evaluate version strategies

   Latest LTS versions provide tested stability and updating every 12 weeks balances new features and risk.

3. Step 3: Reject risky options

   Weekly versions updated too often can cause instability; old LTS without updates risks security issues.

4. Final Answer:

   Use the latest LTS version and update it every 12 weeks -> Option A

5. Quick Check:

   LTS + regular updates = stable and current [OK]

Hint: Choose LTS with regular updates for production [OK]

Common Mistakes:

• Choosing weekly versions for production without caution
• Never updating Jenkins risking security
• Updating weekly versions too infrequently