DevOps Pipelines, CI/CD, and Container Orchestration, A Practical Guide

DevOps Concepts: Pipelines, CI/CD, Containers, and Orchestration

Pipelines and Git

A pipeline in software development is a set of automated processes that helps developers to compile, build, test, and deploy their code. Git, being a distributed version control system, is widely integrated with pipelines to ensure smooth collaboration.

CI/CD

CI/CD stands for Continuous Integration and Continuous Deployment (or Delivery). It’s a methodology where developers frequently integrate their code into a shared repository, followed by automated testing and deployment to production.

DIY Tools: Jenkins, GitLab

You can set up DIY tools like Jenkins and GitLab to create custom CI/CD pipelines tailored to your project. These tools offer flexibility and control but require configuration and management.

SaaS CI/CD Tools

Several SaaS (Software as a Service) CI/CD tools are available, like GitHub, Bitbucket, GitLab, Travis CI, and CircleCI. These platforms simplify pipeline setup with pre-built integrations and minimal configuration.

Git Commands: Commit and Push

Two essential Git commands:

• Commit: Stages your local changes to the Git repository.
• Push: Sends your committed changes to a remote repository.

GitHub Actions

GitHub Actions is a CI/CD platform integrated with GitHub that allows you to automate workflows, from building and testing code to deployment.

GitLab vs Jenkins

GitLab offers a more integrated experience, combining repository management with CI/CD, while Jenkins is a standalone tool offering more flexibility for complex builds.

Pull Requests and PR Approval

A Pull Request (PR) is a way to propose code changes in Git repositories, which must be reviewed and approved by collaborators. An approval list is typically maintained to ensure only authorized users can merge code.

Style Guides

A style guide ensures consistency in code formatting, naming conventions, and overall readability across the team. Adhering to a style guide helps maintain code quality.

Fork, Clone, and Repositories

• Fork: Create a personal copy of a repository to work on.
• Clone: Download a local copy of the repository to your machine.
• Repository (Repo): A version-controlled directory where your project resides.

Linting: Static and Dynamic Analysis

Linting is the process of running static analysis on your code to find syntax errors and stylistic inconsistencies. Dynamic analysis involves executing the program to detect runtime errors.

Azure DevOps and AWS DevOps

Both Azure DevOps and AWS DevOps provide comprehensive tools for CI/CD, infrastructure as code (IaC), and monitoring to enable fast, reliable deployments.

Git Blame

Git Blame is used for retrospective analysis, showing which commits made changes to a file. It’s useful for root cause analysis when debugging.

Rebase vs Merge

When integrating changes, rebase is often preferred over merge as it creates a cleaner commit history by applying your changes on top of the latest branch.

Worst Practices to Avoid

• Not using .env files securely.
• Using the -m flag in Git to write minimal commit messages.
• Not committing regularly.

SourceTree and Versioning

SourceTree is a GUI-based Git client that helps manage Git repositories visually. Versioning (e.g., v1.0, v2.0) helps in tracking software releases.

GitOps

GitOps is a way of automating infrastructure and applications through Git, treating Git as the single source of truth for infrastructure code.

Cloud-Native and CNCF

Cloud-native applications are designed to leverage cloud infrastructure efficiently, often following microservice architectures. The CNCF (Cloud Native Computing Foundation) governs projects like Kubernetes, Helm, and Prometheus.

Docker vs Virtual Machines

• Docker: Lightweight containers that share the host’s OS kernel, ideal for microservices.
• Virtual Machines (VMs): Full OS environments with their own kernels, providing isolated environments but at a higher resource cost.

LXC and System Containers

LXC (Linux Containers) are lightweight virtualization methods that use the host OS to isolate system containers, offering near-native performance.

Container Runtime Interfaces

CRI (Container Runtime Interface) is a standard interface that container orchestration tools like Kubernetes use to interact with container runtimes. Examples include:

• Docker Engine
• Containerd
• Kata
• Rkt
• CRI-O

Dockerfile and Multi-Stage Builds

A Dockerfile is a script that defines the layers of a Docker image. Each RUN command adds a new layer. Multi-stage builds help minimize the final image size by using multiple temporary images.

Stateless vs Stateful Containers

• Stateless containers don’t store any persistent data. When they restart, they lose all information.
• Stateful containers use volumes to persist data across container restarts.

Alpine and Arch Linux

Alpine and Arch Linux are lightweight, minimal operating systems often used in Docker containers to keep image sizes small.

Snapshot and Ephemeral Containers

• A snapshot captures the state of a container or volume at a specific point.
• Ephemeral containers exist only for a short period, usually to run tasks and then terminate.

Container Registries: DockerHub, GCR, ECR

Registries like DockerHub, GCR.io (Google Container Registry), and ECR (Elastic Container Registry) are used to store and distribute Docker images.

Dangling Images

Dangling images are orphaned Docker images that aren’t associated with any container. These can be cleaned up to free space.

Container Orchestration

Container orchestration platforms like Kubernetes, Amazon ECS, GKE, and EKS help manage and scale containers automatically by ensuring the desired state matches the actual state.

Kubernetes: The Hard Way

Kubernetes: The Hard Way is a book by Kelsey Hightower that teaches how to manually set up Kubernetes clusters without automated tools.

Infrastructure as Code (IaC)

Tools like Terraform and Ansible are used to manage infrastructure declaratively, treating infrastructure as code. This automates provisioning, scaling, and configuration management.

Stateful Workloads in Kubernetes

In Kubernetes, Persistent Volume Claims (PVCs) are used to request storage for stateful workloads that need data persistence across container restarts.

Cloudflare Workers

Cloudflare Workers are a serverless platform that allows you to run scripts at the edge, close to users, reducing latency for web apps.

Container Build Strategies: Multistage vs Multi-container

• Multistage builds optimize Docker images by combining multiple build stages into a single image.
• Multi-container setups involve running multiple containers together to form a single application, often managed by tools like Docker Compose or Kubernetes.

Configuration Management Tools

Tools like Ansible, Chef, Puppet, and Salt are used to automate configuration management across large clusters of servers, ensuring consistent environments.