devops

Docker Compose orchestrates multi-container applications with a single YAML file. The docker-compose.yml defines services, networks, and volumes declaratively. Each service maps to a container with its own image, ports, environment, and dependencies.

Optimized Docker images reduce build time, storage, and attack surface. Alpine-based images start at 5MB versus 100MB+ for Debian. Multi-stage builds separate build tools from runtime—final image contains only production artifacts. Layer ordering matt

GitLab CI/CD uses .gitlab-ci.yml for pipeline configuration. Pipelines consist of stages that run sequentially. Jobs within the same stage run in parallel. The image key sets the Docker image for each job. variables define global or job-level environm

Terraform state tracks the mapping between configuration and real infrastructure. Remote state backends like S3, GCS, or Terraform Cloud enable team collaboration. DynamoDB provides state locking to prevent concurrent modifications. The terraform_remo

Prometheus collects and stores time-series metrics via a pull model. It scrapes /metrics endpoints at configured intervals. The prometheus.yml defines scrape_configs with target discovery. static_configs list fixed targets while kubernetes_sd_configs

Kubernetes orchestrates containerized applications at scale. Deployments manage ReplicaSets ensuring desired pod count. Services expose pods with stable endpoints. ConfigMaps externalize configuration. Secrets store sensitive data. Resource limits pre

Makefiles provide a simple, universal task runner for DevOps workflows. Targets define named tasks with optional dependencies. The .PHONY declaration prevents conflicts with files of the same name. Variables set at the top configure reusable values. $

Linux system administration is fundamental to DevOps. Process management with ps, top, htop monitors system activity. systemctl manages systemd services—start, stop, enable, disable. Disk management with df, du, lsblk, mount handles storage. journalct

Effective Git workflows enable smooth team collaboration. Git Flow uses main, develop, feature/*, release/*, and hotfix/* branches. GitHub Flow simplifies to main plus short-lived feature branches with pull requests. Trunk-based development commits di

Ansible automates server configuration and application deployment without agents. Playbooks are YAML files describing desired system state. hosts targets machines from the inventory. tasks execute modules like apt, copy, template, service, and user. h

Environment variables configure applications without code changes. The twelve-factor app methodology stores config in the environment. .env files provide local defaults—never commit them to Git. dotenv libraries load .env files in development. Product

Docker packages applications into lightweight, portable containers. A Dockerfile defines build instructions—each instruction creates an immutable layer. The FROM directive sets the base image. COPY and ADD bring files into the image. RUN executes comm