Jenkins Architecture Fundamentals
Jenkins Architecture Fundamentals
Core Architecture Components
Master Server Architecture
Key Components
- Jenkins Web Interface
- Dashboard and job management
- Configuration interface
- Plugin management console
- System monitoring views
- Build Executor
- Job scheduling system
- Resource allocation
- Queue management
- Load balancing
- Plugin System
- Core plugin architecture
- Plugin lifecycle management
- Extension points
- Plugin dependencies
Agent Architecture
Agent Types
- Static Agents
- Permanent connection to master
- Dedicated resources
- Consistent environment
- Ideal for stable workloads
- Dynamic Agents
- Cloud-based provisioning
- On-demand scaling
- Resource optimization
- Cost-effective for variable loads
Agent Communication
graph TD
A[Master] -->|JNLP/SSH| B[Agent 1]
A -->|JNLP/SSH| C[Agent 2]
A -->|JNLP/SSH| D[Agent N]
System Requirements
Hardware Requirements
Master Node
- Minimum Requirements:
- CPU: 4 cores
- RAM: 8GB
- Disk: 50GB
- Recommended Specifications:
- CPU: 8+ cores
- RAM: 16GB+
- Disk: 100GB+ SSD
Agent Nodes
- Base Requirements:
- CPU: 2 cores
- RAM: 4GB
- Disk: 20GB
- Workload-Specific Sizing:
# Example resource calculation CONCURRENT_BUILDS=5 RAM_PER_BUILD=2GB TOTAL_RAM=$((CONCURRENT_BUILDS * RAM_PER_BUILD + 2))GB
Network Requirements
Connectivity
- Port Requirements:
```plaintext
Jenkins Master:
- 8080: Web interface (HTTP)
- 8443: Web interface (HTTPS)
- 50000: Agent communication
- 22: SSH (if using SSH agents)
Agents:
- Outbound access to master
- Build-specific ports
- Container registry ports (if using containers) ```
- Firewall Considerations:
- Allow master-agent communication
- Configure proxy settings if needed
- Enable SSL/TLS for secure communication
- Set up network segmentation
Performance Optimization
JVM Tuning
- Memory Settings:
# Recommended JVM settings export JENKINS_JAVA_OPTS="-Xmx4g -Xms2g \ -XX:+UseG1GC \ -XX:+ExplicitGCInvokesConcurrent \ -XX:+ParallelRefProcEnabled \ -XX:+UseStringDeduplication \ -XX:+HeapDumpOnOutOfMemoryError"
- Garbage Collection:
- Monitor GC logs
- Adjust heap size based on usage
- Configure GC algorithm
System Monitoring
- Key Metrics:
- CPU usage
- Memory consumption
- Disk I/O
- Network latency
- Build queue length
- Monitoring Tools:
```yaml
Prometheus configuration
scrape_configs:
- job_name: ‘jenkins’
metrics_path: ‘/prometheus’
static_configs:
- targets: [‘jenkins:8080’] ```
- job_name: ‘jenkins’
metrics_path: ‘/prometheus’
static_configs:
Troubleshooting Guide
Common Issues
- Memory Issues:
# Check memory usage jmap -heap <jenkins_pid> # Analyze heap dump jhat jenkins_heap.hprof
- Performance Problems:
- Review system logs
- Check resource utilization
- Analyze build history
- Monitor plugin performance
- Master-agent communication
- Source control access
- Artifact repository access
- Container registry access
Scaling Considerations
Vertical Scaling
Master Node Scaling
- CPU Optimization:
- Monitor build queue
- Track system load
- Analyze GC behavior
- Optimize thread pools
- Memory Management:
// Example JVM settings JAVA_OPTS="-Xmx4g -Xms4g -XX:+UseG1GC"
Horizontal Scaling
Agent Pool Management
- Static Pool:
// Jenkinsfile example pipeline { agent { label 'high-cpu' } stages { // Pipeline stages } }
- Dynamic Scaling:
```yaml
Kubernetes agent example
apiVersion: v1 kind: Pod metadata: labels: type: jenkins-agent spec: containers:
- name: maven image: maven:3.8.4 ```
Data Storage Strategy
File System Storage
Directory Structure
/var/jenkins_home/
├── jobs/ # Job configurations
├── plugins/ # Installed plugins
├── secrets/ # Security credentials
├── nodes/ # Agent configurations
└── workspace/ # Build workspaces
Backup Strategy
Critical Data
- Configuration Files:
# Backup script example tar czf jenkins_backup.tar.gz \ /var/jenkins_home/jobs \ /var/jenkins_home/plugins \ /var/jenkins_home/secrets
- Job History:
- Build logs
- Artifacts
- Test results
- Coverage reports
Performance Optimization
Build Optimization
Pipeline Optimization
- Parallel Execution:
parallel { stage('Unit Tests') { steps { /* test steps */ } } stage('Integration Tests') { steps { /* test steps */ } } }
- Resource Management:
- Workspace cleanup
- Artifact management
- Cache utilization
System Tuning
JVM Optimization
- Memory Settings:
export JAVA_OPTS="-Xmx4g -Xms4g \ -XX:+UseG1GC \ -XX:+DisableExplicitGC \ -XX:+AlwaysPreTouch"
- Garbage Collection:
- Monitor GC logs
- Adjust collection strategy
- Optimize heap size
Hands-on Exercise
Basic Setup
- Install Jenkins Master:
# Ubuntu/Debian wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add - sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list' sudo apt update sudo apt install jenkins
- Configure System Resources:
# Edit Jenkins service file sudo systemctl edit jenkins # Add resource limits [Service] LimitNOFILE=8192 Environment="JAVA_OPTS=-Xmx2g -Xms2g"
Agent Configuration
- Create Static Agent:
# On agent machine mkdir -p /var/jenkins_agent wget http://jenkins-master:8080/jnlpJars/agent.jar java -jar agent.jar -jnlpUrl http://jenkins-master:8080/computer/agent1/slave-agent.jnlp
- Test Agent Connection:
- Create test job
- Assign to new agent
- Verify execution