DevOps is a set of practices that combines software development (Dev) and IT operations (Ops) to shorten the software development lifecycle (SDLC) while ensuring high quality and reliability.

1. Collaboration – Breaking silos between Dev & Ops
2. Automation – CI/CD, Infrastructure as Code (IaC)
3. Continuous Integration & Continuous Deployment (CI/CD)
4. Monitoring & Logging – Observability, real-time feedback
5. Security (DevSecOps) – Security integrated into SDLC

1. Plan – Jira, Trello
2. Develop – Git, GitHub
3. Build – Maven, Gradle
4. Test – Selenium, JUnit
5. Release – GitHub Actions, Jenkins
6. Deploy – Kubernetes, Docker
7. Monitor – Prometheus, Grafana

• CI/CD: Jenkins, GitHub Actions, GitLab CI
• Configuration Management: Ansible, Puppet
• Containerization: Docker, Kubernetes
• Monitoring & Logging: Prometheus, Grafana, ELK Stack

CI/CD is a DevOps practice that automates code integration, testing, and deployment.

• Continuous Integration (CI) – Automates code merging & testing.
• Continuous Deployment (CD) – Automates production releases.

Version control tracks code changes, allowing collaboration. Git is widely used because of:

• Branching & Merging – Parallel development
• Distributed Version Control – No central dependency

IaC automates infrastructure provisioning using code. Example: Terraform, Ansible, CloudFormation.

Using Ansible, Puppet, Chef, engineers automate configuration setup, ensuring consistency.

A container packages an app with dependencies, ensuring it runs identically anywhere. Docker simplifies container management.

Kubernetes orchestrates containers, automating deployment, scaling, and networking.

Microservices break apps into independent, loosely coupled services for scalability and agility.

A reverse proxy (e.g., Nginx) balances traffic, improves security, and caches content.

Using tools like Prometheus, Grafana, ELK Stack to track logs, metrics, and alerts.

Logging helps capture system and application events, allowing developers and operations teams to diagnose issues and improve performance.

• Tools: ELK Stack, Loki, Splunk

Environment variables store configuration settings (e.g., API keys, DB credentials). They help manage different environments (Dev, QA, Production) without modifying code.

A load balancer distributes traffic across multiple servers to improve availability, reliability, and performance.

• Example: Nginx, AWS ELB

Service discovery helps microservices locate and communicate with each other dynamically.

• Examples: Consul, Eureka, Kubernetes Service Discovery

1. Automated Testing – Detects issues early
2. Logging & Monitoring – Alerts and logs errors
3. Rollback Strategy – Deploys a stable version if errors occur

A strategy where two environments (Blue & Green) exist:

• Blue – Active
• Green – Staging (new version)
  Switching traffic to Green reduces downtime.

• Terraform: Declarative, cloud provisioning
• Ansible: Configuration management, procedural

A small subset of users receives the new update before a full rollout.

Helm automates Kubernetes app deployment using predefined templates.

A rolling update gradually replaces old pods with new ones without downtime.

1. HashiCorp Vault
2. AWS Secrets Manager
3. Kubernetes Secrets

Infrastructure where components are never modified after deployment, reducing configuration drift.

1. ClusterIP – Internal communication
2. NodePort – Exposes a service on a port
3. LoadBalancer – External traffic balancing

• Uses exporters to collect metrics
• Stores time-series data
• Alerts on anomalies via Alertmanager

• Ansible – Agentless, YAML-based, simple
• Chef/Puppet – Require agents, more complex

1. Multi-AZ Deployments
2. Load Balancing
3. Auto Scaling

Using StatefulSets, Persistent Volumes, and Storage Classes.

A sidecar runs alongside the main app container to handle logging, monitoring, or proxying.

1. Static Code Analysis (SAST)
2. Container Scanning
3. Dependency Scanning

"Shift Left" integrates security earlier in the development cycle, reducing vulnerabilities.

A DaemonSet ensures that a pod runs on every node.

• Proactive – Prevents issues (threshold-based alerts)
• Reactive – Responds to issues (post-failure logs)

A service mesh (e.g., Istio) manages service-to-service communication, security, and monitoring.

1. RBAC (Role-Based Access Control)
2. Network Policies
3. Secrets Management

1. Identify the failure (logs, monitoring tools)
2. Rollback the last stable version
3. Fix and test the issue
4. Redeploy the fixed version
5. Post-mortem analysis

GitOps automates infrastructure and app deployment using Git as the single source of truth.

1. Distributed Tracing (Jaeger, Zipkin)
2. Centralized Logging (ELK, Loki)
3. Metrics (Prometheus, Grafana)

A service mesh (e.g., Istio) provides:

• mTLS (Mutual TLS)
• Traffic control & observability

OPA enforces security policies in cloud environments.

1. Kubernetes Secrets
2. Vault by HashiCorp
3. AWS Secrets Manager

1. Pod Auto-scaling (HPA, VPA)
2. Resource Limits & Requests
3. Efficient Networking

1. Automated Policy Enforcement (OPA, Kyverno)
2. Audit Logging
3. Access Control & Role-Based Permissions

Chaos Engineering tests system resilience by simulating failures (e.g., Chaos Monkey).

1. Blue-Green Deployments
2. Canary Releases
3. Rolling Updates

1. Use a common IaC tool (Terraform)
2. Standardized security policies
3. Cross-cloud monitoring

1. Use minimal base images (Alpine, Distroless)
2. Scan images for vulnerabilities (Trivy, Clair)

1. Rolling Updates
2. Node Drain & Replace
3. Backup & Disaster Recovery Plan

PaC enforces policies using code-driven automation (e.g., Open Policy Agent).

1. kubectl describe pod
2. kubectl logs
3. kubectl get events

eBPF (Extended Berkeley Packet Filter) runs sandboxed programs inside the Linux kernel for deep observability.

1. Backup etcd
2. Cluster snapshots
3. Multi-region deployments

Progressive delivery deploys updates gradually using techniques like feature flags and A/B testing.

Kubernetes Operators automate complex application deployment and lifecycle management.

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