Tools: what is inside Jenkins

🔹 LEFT SIDE MENU ## ➕ New Item ## Types you can create: ## When to use: ## Build History ## When used: ## Project Relationship ## Check File Fingerprint ## 🔹 BUILD QUEUE ## 🔹 BUILD EXECUTOR STATUS ## Built-In Node (0/2) ## linux (offline) ## mac-agent (0/1) ## node-mac1 (0/1) ## 🔹 CENTER TABLE (MAIN JOB LIST) ## 🔹 COLUMN: S ## S = Status ## 🔹 COLUMN: W ## W = Weather ## 🔹 COLUMN: Name ## 🔹 COLUMN: Last Success ## 🔹 COLUMN: Last Failure ## 🔹 COLUMN: Last Duration ## 🔹 COLUMN: Coverage ## 🔹 RIGHT SIDE PLAY BUTTON ▶️ ## 🔹 JOB TYPES (Based on Icons) ## basic-pipeline ☀️ ## devops-beginner-lab ☁️ ## eks-text 🔴 ## netflix1 🔵 ## 🔹 ICONS AT BOTTOM: S M L ## 🔥 HOW DEVOPS USES THIS PAGE DAILY ## 🔥 WHAT INTERVIEWERS EXPECT YOU TO SAY ## 🔥 WHEN TO USE EACH SECTION ## 🔥 Production-Level Behavior ## 🔹 SYSTEM CONFIGURATION ## 1️⃣ System ## What it is: ## Why we use it: ## What you find inside: ## In Production: ## 2️⃣ Tools ## What it is: ## What inside: ## Production usage: ## 3️⃣ Plugins ## What it is: ## What you manage: ## Production: ## 4️⃣ Nodes ## What it is: ## Inside: ## Production: ## 5️⃣ Clouds ## What it is: ## Examples: ## Production: ## 6️⃣ Appearance ## What it is: ## Inside: ## 🔹 SECURITY SECTION ## 7️⃣ Security ## What it is: ## Inside: ## Production: ## 8️⃣ Credentials ## What it is: ## Types: ## Scope: ## Production: ## 9️⃣ Credential Providers ## What it is: ## Examples: ## 🔹 STATUS INFORMATION ## 🔟 System Information ## What it is: ## What inside: ## 1️⃣1️⃣ System Log ## What it is: ## 1️⃣2️⃣ Load Statistics ## What it is: ## 1️⃣3️⃣ About Jenkins ## Shows: ## 🔹 TROUBLESHOOTING ## 🔥 How DevOps Uses This Page in Real Life ## 🎯 Interview Tip ## 🔹 GENERAL ## Home directory ## Why important: ## Production: ## System Message ## Production: ## Computer Retention Check Interval ## Production: ## Quiet Period ## Production: ## SCM Checkout Retry Count ## Production: ## Restrict Project Naming ## Production: ## 🔹 JENKINS LOCATION ## Jenkins URL ## Production: ## System Admin Email ## Production: ## Resource Root URL ## Production: ## 🔹 GLOBAL PROPERTIES ## Environment Variables ## Production: ## Disable deferred wipeout ## 🔹 DISK SPACE MONITORING ## Production: ## 🔹 TOOL LOCATIONS ## 🔹 PIPELINE SPEED / DURABILITY ## Options: ## Production: ## 🔹 USAGE STATISTICS ## 🔹 HTTP PROXY ## Production: ## 🔹 GLOBAL BUILD TIMEOUT ## Production: ## 🔹 BUILD DISCARDERS ## Production: ## 🔹 GITHUB SECTION ## GitHub Servers ## Production: ## GitHub API rate limiting ## 🔹 GLOBAL PIPELINE LIBRARIES ## Trusted Pipeline Libraries ## Production: ## Untrusted Libraries ## 🔹 GIT PLUGIN ## Global user.name / user.email ## Production: ## 🔹 SHELL ## Shell executable ## 🔹 EMAIL CONFIGURATION ## SMTP Server ## Production: ## Default recipients ## Extended Email Notification ## 🔹 TIMESTAMPER ## 🔹 FINGERPRINTS ## 🔹 ADMINISTRATIVE MONITORS ## 🔹 NOTIFICATION URL ## 🔹 GIT PERFORMANCE OPTIONS ## 🔹 BUILD TIMEOUT PLUGIN ## 🔹 THROTTLING ## 🔥 REAL PRODUCTION PRIORITIES ## 🎯 Interview Answer (Senior Level) ## 1️⃣ What Happens When You Click a Job ## 2️⃣ Full Breakdown of a Pipeline Job Page ## 🔹 A) Build History (Left Side) ## 🔹 B) Stage View (Very Important) ## 🔹 C) Pipeline Syntax ## 🔹 D) Configure ## 3️⃣ Console Output Debugging (Most Important Skill) ## 🔍 How DevOps Debugs ## Interview Tip ## 4️⃣ Replay vs Rebuild ## 🔹 Replay (Pipeline Only) ## 🔹 Rebuild ## Difference ## 5️⃣ Multibranch Pipeline – Deep Explanation ## How It Works ## Why It’s Powerful ## DevOps Setup ## Interview Answer ## 6️⃣ Blue Ocean View ## What It Shows ## Why Use It ## When Used in Production ## 🔥 Real Production Flow Shows all builds across all jobs. • Debug past failures • Audit who deployed • Rollback investigation Production: Very important for audit tracking. Shows upstream/downstream job relationships. Example: Job A → triggers → Job B Tracks artifact usage. Example: Which build produced this artifact? Shows builds waiting to run. If busy: → Means agents are overloaded. This is VERY important. Executors = parallel job slots. Agent is disconnected. 1 executor, currently idle. | S | W | Name | Last Success | Last Failure | Last Duration | Coverage | Let’s break everything. 🟢 Green check → Last build successful 🔴 Red X → Last build failed 🔵 Blue circle → Never built ☀️ Sun icon → Pipeline job ☁️ Cloud icon → Multibranch job When DevOps looks: First thing → check S column. Indicates build stability trend. ☀️ Sunny → Stable ⛅ Partly cloudy → Some failures 🌧 Rain → Many failures ☁️ Cloud → New job Used to: See overall health trend quickly. Interview favorite topic. Example: 2 days 22 hr #8 Used to: Check deployment freshness. Shows: Last failed build number. If recent: Needs investigation. If build suddenly jumps from 2 min → 20 min → investigate. If test coverage plugin installed. Shows: Code coverage percentage. Used in: Quality gates. Manual build trigger. Looking at your screenshot: Sun icon → Pipeline job. Cloud icon → Multibranch pipeline. Usually connected to GitHub repo. Red status → failed last build. DevOps should: Click → Console Output → Debug. Blue circle → never built. This changes icon size: If asked: “What do you monitor on Jenkins dashboard?” • Build health • Agent availability • Queue size • Build duration trends • Success/failure rates • Deployment recency • Code coverage That shows senior understanding. This is Manage Jenkins page — this is the brain control panel of Jenkins. As a DevOps engineer (especially with 6+ years), you must clearly understand what each section does. Global Jenkins configuration page. To configure core Jenkins behavior. Defines tool installations Jenkins can use. So pipelines can use tools consistently. Prevents “works locally but fails in Jenkins”. Jenkins extension marketplace. Jenkins core is minimal. Plugins add power. Common Production Plugins: Manage Jenkins agents (workers). Jenkins master should NOT run heavy builds. Important interview topic. Dynamic agent provisioning. Auto-create build agents when needed. This is modern setup. Production: Not critical, but sometimes used for branding. Authentication & authorization config. Without security Jenkins is dangerous. Never hardcode secrets in Jenkinsfile. Integration with external secret systems. Production: Used in secure enterprise setups. Jenkins runtime details. Production: Used for troubleshooting. Production: DevOps checks here when: Production: Used before: Depends on plugins installed. DevOps responsibilities: DevOps: Owns the entire "Manage Jenkins" page. If interviewer asks: “What does a DevOps engineer manage in Jenkins?” • Global configuration • Security & RBAC • Agent scaling • Plugin lifecycle • Credentials management • Backup & upgrade strategy • Performance monitoring That is senior-level answer. Manage Jenkins → System page (the most important global configuration page). Default: /var/lib/jenkins Where Jenkins stores: If you lose this → you lose Jenkins. Banner shown on top of Jenkins UI. Used for announcements. How often Jenkins checks if agents should be disconnected. Important when using: Delay before starting build after trigger. Avoid triggering multiple builds from rapid commits. Often set to 0 or 5 seconds. How many times to retry Git checkout if it fails. Network glitches happen. Set to 2–3 to avoid random failures. Controls allowed characters in job names. Prevents bad naming conventions. Public URL of Jenkins. Must be correct if behind: Admin email used for system notifications. Serve static resources from CDN. Used in large enterprise setups. Global variables available in all jobs. Advanced disk cleanup option. Threshold warnings if disk low. Overrides default tool paths. Production: Used when: Controls how pipeline data is saved. If critical builds → use MAX durability If performance priority → use performance mode Production: Usually disabled in enterprise. Required in corporate networks. Stop builds after time limit. Auto delete old builds. Example: Keep last 10 builds. Prevents disk overflow. Configure GitHub API access. Avoid hitting GitHub limits. Production: Important for large teams. Shared reusable pipeline code. Trusted = can use advanced Groovy. Sets Git identity for Jenkins. Production: Change to: Configure mail server. Global email recipients. Advanced email plugin. Used heavily in production. Adds timestamps to console logs. Production: Always enabled. Makes debugging easier. Tracks artifact usage across jobs. Warnings shown to admins. Production: Never disable unless necessary. Webhook for external system. Advanced Git plugin tuning. Used rarely unless performance issues. Allows per-build timeout. Production: Prevents runaway builds. Limit concurrent builds. As DevOps, you MUST configure: Everything else depends on company size. If asked: “What do you configure in Manage Jenkins → System?” That is a strong senior DevOps answer. When you click a job (example: basic-pipeline), Jenkins opens the Job Page. Let’s break it section by section. When you click a build → you enter Build Details page. If it's a Declarative Pipeline: | Checkout | Build | Test | Deploy | DevOps uses this daily. Very helpful for beginners. Opens job configuration page. Production: DevOps locks this down. Developers only edit Jenkinsfile in Git. When you click a build → click Console Output This shows step-by-step execution. Step 1: Scroll to bottom Step 2: Look for: Step 3: Scroll slightly above error. ❌ Git authentication failed ❌ Docker not installed ❌ kubectl not found ❌ Permission denied ❌ AWS credentials missing If asked: “How do you debug Jenkins pipeline?” Replay allows you to: Edit Jenkinsfile directly in Jenkins UI Re-run build without committing to Git ⚠️ Production: Usually restricted to admins. Rebuild simply: Runs same build again. No code modification. This is modern Jenkins setup. Instead of 1 job per branch, Jenkins auto-creates jobs per branch. Multibranch automatically creates: “What is Multibranch pipeline?” Automatically creates and manages pipeline jobs for each branch in a repository, allowing independent CI/CD per branch and PR. Blue Ocean = Modern Jenkins UI plugin. Better visualization. Instead of classic stage view, it shows: Graphical pipeline flow: Start → Checkout → Build → Test → Deploy Developer pushes code → GitHub webhook → Jenkins receives trigger → Multibranch identifies branch → Pipeline runs → Build Docker → Push to ECR → Deploy to EKS → Update GitHub commit status → Send Slack notification All visible inside job page. Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse CODE_BLOCK: withCredentials {} Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: withCredentials {} CODE_BLOCK: withCredentials {} CODE_BLOCK: https://jenkins.company.com Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: https://jenkins.company.com CODE_BLOCK: https://jenkins.company.com CODE_BLOCK: ENV=prod REGION=us-east-1 Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: ENV=prod REGION=us-east-1 CODE_BLOCK: ENV=prod REGION=us-east-1 CODE_BLOCK: vars/dockerBuild.groovy Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: vars/dockerBuild.groovy CODE_BLOCK: vars/dockerBuild.groovy CODE_BLOCK: /bin/sh Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: /bin/bash Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: smtp.gmail.com Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: smtp.gmail.com CODE_BLOCK: smtp.gmail.com CODE_BLOCK: #8 #7 #6 Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: Cloning repository... Building Docker image... Pushing to ECR... kubectl apply... Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: Cloning repository... Building Docker image... Pushing to ECR... kubectl apply... CODE_BLOCK: Cloning repository... Building Docker image... Pushing to ECR... kubectl apply... CODE_BLOCK: ERROR: Exception: script returned exit code 1 Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: ERROR: Exception: script returned exit code 1 CODE_BLOCK: ERROR: Exception: script returned exit code 1 CODE_BLOCK: main dev feature/login feature/payment Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: main dev feature/login feature/payment CODE_BLOCK: main dev feature/login feature/payment - Freestyle project - Multibranch Pipeline - Organization Folder - Creates Pipeline jobs - Creates folder structure (prod/dev) - Creates multibranch for GitHub repos - Microservice pipelines - Deployment chains - Artifact traceability - Large enterprises - Add more agents - Debug stuck jobs - 2 executors available - Restart agent - Console output - Build history - Pipeline view - Last successful build was build #8 - Ran 2 days ago - Detect performance issues - Identify slow builds - Capacity planning - Testing pipeline - Re-running after fix - Emergency deployment - Open Jenkins dashboard - Look at S column - Check for red builds - Check Build Queue - Check agent status - Monitor trends (W column) - Check build duration spikes - Queue growing → scale agents - Agent offline → fix SSH or Kubernetes - Frequent failures → review pipeline logic - Long duration → optimize build - No recent success → deployment stale - Jenkins URL - Number of executors - Environment variables - Email configuration (SMTP) - GitHub server settings - Global properties - Quiet period - Build discarders - Global pipeline libraries (important!) - Slack configuration - Configure Jenkins URL (behind ALB or NGINX) - Setup email notifications - Set global environment variables - Set up shared libraries - Configure webhook integrations - Terraform (if plugin installed) - Auto-install tools - Define tool versions - Correct Java version - Specific Maven version - Git version compatibility - Docker CLI availability - Install plugins - Update plugins - Disable plugins - Remove plugins - Docker Pipeline - Credentials Binding - Artifactory - Role-based authorization - Carefully upgrades plugins - Tests in staging - Avoids breaking production - Monitors plugin vulnerabilities - Built-in node (master) - Add new agent - Label agents - Configure executors - Monitor disk / memory - Uses EC2 agents - Uses Kubernetes dynamic agents - Uses Docker agents - Labels agents (linux, docker, prod, test) - Kubernetes cloud - AWS EC2 cloud - Azure cloud - Configure Kubernetes plugin - Jenkins creates pod per build - Auto scales - No idle servers - Blue Ocean UI - System message - Enable security - LDAP integration - GitHub OAuth - Matrix-based security - Role-based access - CSRF protection - Enable authentication - Restrict admin rights - Disable anonymous access - Enable CSRF - Username/password - Secret text - AWS credentials - Certificates - GitHub tokens - DockerHub creds - AWS IAM creds - Kubernetes tokens - HashiCorp Vault - AWS Secrets Manager - Azure Key Vault - Java version - Memory usage - Environment variables - Installed plugins list - Plugin errors - Security issues - Thread issues - Disk warnings - Jenkins won’t start - Plugin crashes - Builds fail unexpectedly - Decide scaling agents - Identify bottlenecks - Justify infrastructure changes - Core version - Plugin compatibility checks - Install Jenkins - Configure security - Install plugins - Configure tools - Configure shared libraries - Store credentials - Enable backups - Monitor disk space - Upgrade safely - Write Jenkinsfile - Trigger builds - Build history - Credentials (encrypted) - Backs this up - Mounts it to EBS/EFS - Monitors disk usage - Migrates this during server move - “Maintenance at 10PM” - “Upgrade scheduled” - “Do not run heavy builds” - Dynamic EC2 agents - Kubernetes agents - Email links - GitHub integration - Reverse proxy - Failure alerts - System warnings - Global configs - Shared settings - Proxy config - Build failures - Jenkins crash - Tools installed manually - Custom Docker setups - Maximum durability - Performance optimized - Stuck builds - Infinite loops - Commit status - Personal access token - Enterprise GitHub - Docker build function - ECR push function - Terraform deploy function - Jenkins pushes tags - Auto version bump - GitOps commits - Build failure alerts - Release notifications - Custom templates - Attach logs - Conditional sending - Large artifact pipelines - Traceability - Monitoring systems - Protect resources - Avoid overload - Jenkins URL - Credentials - Build discarder - Global library - Disk monitoring - GitHub integration - Pipeline durability - Backup strategy - Global environment configuration - SCM retry & quiet period tuning - Agent retention policies - Disk monitoring - Build retention - GitHub API integration - Global shared libraries - Email & notification systems - Proxy configuration - Security & credentials - Pipeline durability strategy - Replay (if pipeline) - Pipeline Syntax - Branches (if multibranch) - Build history (#1, #2, #3…) - Stage View (for pipeline) - Last build summary - 🟢 Blue/Green = Success - 🔴 Red = Failed - 🟡 Yellow = Unstable - 🔵 Grey = Aborted - Success / Fail - Parallel stages if any - Quick failure identification - Bottleneck detection - withCredentials - archiveArtifacts - Triggers (GitHub webhook) - Build triggers - Pipeline script (if inline) - Check console output - Identify failing stage - Verify credentials - Re-run locally if needed - Check agent environment - Quick testing - Debugging pipeline logic - Network failure - Temporary issue - External service glitch - feature/login job - feature/payment job - Connect Jenkins to GitHub repo - Jenkins scans repo - Finds branches - Looks for Jenkinsfile in each branch - Creates job per branch - PR builds automatically - Branch isolation - Cleaner structure - CI per feature branch - Use GitHub App or token - Enable webhook - Configure branch sources - Configure scan interval - Clear stage logs - Visual failure highlight - Parallel branch visualization - Easier debugging - Better for demos - Great for beginners - Use it for developers - But DevOps often uses classic view for deep logs