# Day 14 - CI/CD Interview Questions ## **1\. What is the CI/CD process in your organization?** This is a common interview question to understand your real experience. You should answer by describing the tools your organization uses. Example structure explained in your content: * Assume your company uses **Java**. * Jenkins is the main orchestrator. * Different tools are connected with Jenkins: Maven, Sonar, AppScan, Argo CD, Kubernetes, Helm, etc. * Explain how a developer commits code to GitHub. * Jenkins pipeline automatically triggers and pulls the code. * Jenkins builds the code (e.g., with Maven). * It performs code quality checks or security checks (e.g., Sonar, AppScan). * Then the application is promoted to Dev using Argo CD and Kubernetes. * Argo CD watches the Git repository and deploys new versions using updated image tags and Helm charts. * If Kubernetes is difficult, you can say you deploy to EC2 instead. The content also refers to a Jenkins pipeline example in the GitHub repository that updates Kubernetes manifests and lets Argo CD deploy based on GitOps. --- ## **2\. What are the different ways to trigger Jenkins pipelines?** Since Jenkins and GitHub are separate tools, Jenkins must know when new code is pushed. There are **three methods**: * Poll SCM * Build triggers (Cron) * Webhooks Explanation from your content: * Polling and Cron jobs are inefficient because Jenkins repeatedly checks GitHub, which consumes resources and can have time delays. * Webhooks are the best method: * When a developer commits code, GitHub sends a JSON payload to Jenkins. * GitHub notifies Jenkins through an API. * Jenkins receives the payload and triggers the pipeline. --- ## **3\. How to back up Jenkins?** For Jenkins administration roles, backup is important. Summary from your content: * The main folder to back up is **.jenkins** from the Jenkins home directory. * This folder contains jobs, logs, and configuration. * Use tools like **rsync** to sync backups to storage (EBS or other). * Some large organizations store Jenkins data in external databases, so those databases must be backed up as well. * Plugins or user content may need separate backup steps. --- ## **4\. How do you store or handle secrets in Jenkins?** Secrets must never appear in logs or UI. Jenkins provides credential plugins, but the recommended explanation: * Use external secret managers such as **HashiCorp Vault**. * Jenkins integrates with Vault. * Pipelines fetch secrets from Vault during runtime. --- ## **5\. What is the latest version of Jenkins?** Interviewers ask this to check whether you actually use Jenkins regularly. Not knowing the current version can give a bad impression. If you claim to be a CI/CD engineer using Jenkins, you must stay updated. --- ## **6\. What are shared modules in Jenkins?** Shared modules/shared libraries mean: * A DevOps engineer writes a pipeline once. * Many development teams reuse that pipeline. * This avoids each team rewriting the same logic. It’s a reusable pipeline approach. --- ## **7\. Can Jenkins build applications using multiple programming languages with different agents?** Yes. Explanation in your content: * Example: frontend (Node.js), backend (Java), microservice (Python). * Jenkins can run multiple stages using **different Docker agents**. * Each stage uses a separate Docker container with required dependencies. * Containers are removed after pipeline execution, saving resources. --- ## **8\. How to set up Auto Scaling Groups with Jenkins?** Some companies need multiple worker nodes. Explanation: * Jenkins master runs on one EC2 instance. * Many teams may need many worker nodes. * Load can increase during certain periods. * Auto Scaling Groups in AWS automatically add/remove Jenkins worker nodes. * This prevents unused nodes from wasting costs. --- ## **9\. How to add a new worker node in Jenkins?** Summary: * Go to **Manage Jenkins → Manage Nodes and Clouds**. * Add a new node. * Provide IP address, SSH keys, authentication. * Launch the node to make it active. --- ## **10\. How to install plugins in Jenkins?** Two ways: ### **UI Method** * Manage Jenkins → Manage Plugins * Search and install plugins ### **CLI Method** * Use a Java command to install plugins directly * Useful for automation or when installing many plugins at once * Some plugins must be manually uploaded if not available in the plugin catalog. --- ## **11\. What is JNLP and why is it used?** Explanation: * JNLP is a way for Jenkins agents (workers) to communicate with Jenkins master. * You download a JNLP JAR and run it on the agent. * It allows remote launch and communication. * The agent receives build tasks from the master. --- ## **12\. What are some common Jenkins plugins?** Interviewers check your practical experience. The content suggests: * Be familiar with common plugins. * Look at which plugins Jenkins installs by default. * Prepare a list to avoid blanking during interviews. --- ## **Wrap-up** The speaker ends by saying: * These are the main interview questions. * The repository contains detailed answers. * You can submit pull requests if something is missing. * Feedback is welcome, and viewers should subscribe and share.