A Comprehensive Jenkins troubleshooting guide: Common issues and solutions

Jenkins build and pipeline failures

Here are a few common errors that Jenkins users face related to builds and pipelines:

Issue # 1 – Compilation errors

Problem: Code fails to compile due to syntax errors or missing dependencies in the source code.

Detection: You will find compilation errors in the build logs on Jenkins.

Troubleshooting:

• Review the error messages to identify the specific files and lines causing the compilation to fail.
• Fix the syntax errors and compile code locally before retriggering the next pipeline.

Issue # 2 – Missing dependencies

Problem: Pipeline scripts rely on tools, libraries, or plugins that are not available on the Jenkins server or build node.

Detection: You may see errors that indicate missing dependencies, packages, plugins, or shared libraries.

Troubleshooting:

• Ensure required dependencies are installed on the system or managed through package managers within the pipeline.
• Verify plugin compatibility and version requirements. For example, if a plugin expects a later Java version than installed, the build will fail.
• Clean local caches and repositories to prevent stale or corrupt dependencies from causing build failures.

Issue # 3 – Deployment errors

Problem: You are experiencing problems or inconsistencies in deployments.

Detection:

• Applications are not behaving as expected after upgrades.
• Manual intervention is needed after some or all deployments.

Troubleshooting:

• Review and validate deployment targets, credentials, and file paths for accuracy.
• Double-check server addresses, authentication credentials, and file paths specified in the deployment configuration.
• Regularly update deployment scripts to reflect any changes in the deployment environments. It’s prudent to version control deployment scripts and configurations to track changes and enable rollback if necessary.
• Always test deployments in a controlled environment before rolling out to production.

Issue # 4 – Test failures

Problem: Tests within the pipeline are failing. This may be due to potential code issues or incorrect test configurations.

Detection: The test reports generated by the build will highlight failed tests along with the corresponding error messages or stack traces.

Troubleshooting:

• Go through the test failure messages to understand the root cause(s).
• Update the source code to fix the underlying bugs or issues.
• If the code is working as expected, you can review and adjust the test configurations, such as the test data or environment settings.
• Rerun failed tests locally to verify fixes before triggering a new build.

Issue # 5 – Permission issues

Problem: A pipeline lacks the necessary permissions to access files, access resources, or execute certain actions.

Detection: You may observe errors that contain phrases like “permission denied”, “insufficient permissions”, or “access violations”.

Troubleshooting:

• Review pipeline permissions to ensure they have access to the required resources, but remember to grant only the minimum level of access required for each task.
• Leverage Jenkins’s role-based access control for better security.

Issue # 6 – Environment-related problems

Problem: Issues that originate because of discrepancies between the development and deployment environments.

Detection: Build logs may show errors related to missing environment variables, incorrect paths, or incompatible configurations.

Troubleshooting:

• Use environment configuration management tools or frameworks to automate the setup and provisioning of all your development, testing, and production environments.
• Validate environment configurations before triggering builds by performing environment checks or preflight tests.
• Consider using infrastructure-as-code tools to define and manage environment configurations declaratively.

Jenkins resource management issues

Have you been encountering issues related to build concurrency, unavailable agents, or resource exhaustion? Then, the following sections are for you.

Issue # 1 – Available resources exhausted

Problem: Build execution exceeds the available resources (CPU, memory, disk space) on the Jenkins server or build node.

Detection:

• Pipelines that have been running successfully for long periods of time suddenly start failing.
• System monitoring tools indicate resource bottlenecks coinciding with build failures.
• Pipeline logs may show errors related to resource exhaustion.

Troubleshooting:

• Start with a deep examination of the logs to get more context. For example, you may be facing a disk space issue due to a large number of historical log files or core dumps.
• If required, allocate more resources to Jenkins or build nodes.
• Optimize resource-intensive steps within the pipeline.
• If your Jenkins architecture is constantly underdelivering, consider horizontal scaling with additional build nodes.

Issue # 2 – Timeout errors

Problem: Build steps are exceeding the predefined time limit, leading to build failures.

Detection: Error messages mention script execution or similar timeouts.

Troubleshooting:

• Start by examining the Jenkins file logs to pinpoint any slow-running steps.
• If justified, increase the configured timeouts. Otherwise, optimize slow-running steps by breaking them down, or leveraging caching or parallelization.

Issue # 3 – Stalled builds

Problem: The number of concurrent builds has exceeded the available resources, leading to queue buildup.

Detection: You are experiencing long wait times for builds, increased queue length, and potential timeouts.

Troubleshooting:

• Use prioritization plugins like Priority Sorter to implement build queuing strategies, such as dynamic priority assignment based on resource availability.
• Use throttling plugins like Throttle Concurrent Builds to optimize resource utilization and prevent overloading Jenkins agents.
• Analyze the logs of builds that are taking too long to complete. Identify avenues for improvement.

Issue # 4 – Unavailable agents

Problem: Build agents are offline, overloaded, or don’t have the necessary resources to execute builds.

Detection:

• The agent status shows inactive or disconnected. (You can use native plugins like Agent Status or tools like Site24x7’s Jenkins Monitoring Tool to monitor agent statuses.)
• Build logs contain errors related to agent unavailability or resource exhaustion.
• Monitoring tools show high agent utilization.

Troubleshooting:

• Examine the controller and agent logs to identify the cause of agent unavailability. Potential reasons can be network issues, agent misconfigurations, memory exhaustion, or system failures.
• Restart or reconnect offline agents to restore connectivity and resume build execution.
• Consider implementing agent redundancy or failover mechanisms to ensure continuous availability of build resources.

Issue # 5 – Inefficient job scheduling

Problem: Jenkins jobs are scheduled in a suboptimal manner, and you are facing resource conflicts or bottlenecks.

Detection:

• You may find patterns of resource contention or scheduling days after a deep examination of job execution logs.
• Monitoring metrics may highlight that jobs are taking longer than expected to complete.

Troubleshooting:

• Review and optimize job scheduling policies to balance resource usage and minimize conflicts. For example, you can check if certain jobs can be scheduled to off-peak hours to reduce resource contention during peak hours.
• Make scheduling more dynamic and intelligent. For example, you can use the Parameterized Scheduler plugin to schedule a build to run at different times and with different parameters.

Issue # 6 – Overutilization of shared resources

Problem: Multiple Jenkins builds or jobs are competing for access to shared resources.

Detection:

• You may be experiencing performance degradation or failures after provisioning new builds or jobs.
• Monitoring tools are showing high overall resource utilization despite low individual agent usage.

Troubleshooting:

• Implement resource isolation or partitioning to allocate dedicated resources for critical or high-priority builds.
• Consider scaling your Jenkins infrastructure horizontally to distribute workload across multiple nodes and reduce reliance on shared resources.
• Use the Lockable Resources plugin to guarantee exclusive access to specific resources. The plugin ensures that if a resource is in the “locked state” (i.e., acquired by another build), the current build will wait for the resource to be free to acquire it.

Jenkins security management

Next, let’s look at some potential security-related issues in Jenkins deployments and how to overcome them.

Problem # 1 – Insecure plugins and integrations

Description: You may be using an insecure open-source plugin or integration that has exploitable vulnerabilities or bugs.

Solutions:

• Install plugins only from official repositories and reputable developers. Go through plugin reviews and ratings before installation.
• Restrict access for plugins to only the resources and data they absolutely require.
• If you have developed any Jenkins plugins in-house, regularly scan their source code for security hotspots or vulnerabilities.

Problem # 2 – Lack of monitoring

Description: You are not using any monitoring tool to track the health, performance, and security outlook of Jenkins. This can leave your Jenkins environment vulnerable to undetected issues, performance bottlenecks, and even security breaches.

Solutions:

• Use purpose-built monitoring tools like the Jenkins Monitoring Tool from Site24x7 to track the health and performance of Jenkins in real time. Site24x7 allows you to monitor several metric types, including those for nodes, projects, queues, agents, executors, jobs, plugins, and builds.
• Monitor Jenkins logs for potential security incidents and investigate any anomalies promptly.
• Formulate a clear plan to identify, contain, and remediate security breaches to minimize downtime.

Problem # 3 – CSRF protection is disabled

Description: Cross-Site Request Forgery (CSRF) protection prevents attackers from exploiting user sessions to perform unauthorized actions on Jenkins. When it is disabled, Jenkins is vulnerable to CSRF attacks, which can have serious repercussions.

Solutions:

• Go to Manage Jenkins -> Security -> CSRF Protection to enable the feature.
• Stay up to date with the latest Jenkins releases and security patches to steer clear of any vulnerabilities or exploits related to CSRF.

Problem # 4 – Builds are running on the built-in node

Description: Even though it’s possible to run builds on the built-in (master) node, it is discouraged for security, scalability, and performance reasons. The built-in node is primarily meant for managing Jenkins itself and should not be used for executing builds or tasks.

Solutions:

• Update the built-in node configuration to disallow any builds from running on it.
• If needed, set up additional nodes or agents in Jenkins to offload build execution from the built-in node.
• Use node labeling to define which builds should run on specific nodes or agents.

Conclusion

Jenkins is the go-to tool for automating different stages of the software development life cycle. Whether you are a developer, tester, DevOps person, or a production engineer, it offers the tools and features to streamline your workflows and increase your productivity. In this guide, we dissect the most common Jenkins issues, and provide practical solutions to troubleshoot and resolve them. We hope you found it useful.