Mohammad Abu Mattar
Hi, I’m Mohammad Abu Mattar
DevOps engineer, AWS-certified, working in the field since 2017. I run multi-account AWS platforms and production Kubernetes for fintech, where PCI-DSS sets the rules. On this site I write up what worked, what broke, and what I would do differently. Most of my tooling ends up open source.
Blog Posts
Multi-Region Active-Active on AWS: What It Actually Costs You
- Cloud Architecture
- Disaster Recovery
- 08 Sept 2026
- 12 Mins read
Surviving a full regional outage with no downtime is the thing every architecture review eventually asks about, and the answer is usually more expensive than the person asking expects. In a multi-regi
Building a Customizable Image Slider in React Using Hooks, SCSS, and TypeScript
- ReactJS
- TypeScript
- 17 Feb 2023
- 12 Mins read
Introduction In this tutorial, we will be building a customizable image slider in React using hooks, SCSS, and TypeScript. An image slider is a common UI element used in web applications to displa
Caching Strategies with Redis in Node.js and TypeScript
- Backend Development
- Caching
- 23 Aug 2023
- 06 Mins read
Introduction Optimizing application performance is an ongoing job, and caching is one of the most effective ways to do it. Redis, a fast in-memory data store, is a common choice for caching in Nod
Deploying Infrastructure with Terraform in CI/CD Pipelines
- DevOps
- Infrastructure as Code
- 22 Sept 2024
- 04 Mins read
In fast-paced DevOps environments, Infrastructure as Code (IaC) has become a cornerstone for managing and scaling infrastructure efficiently. Terraform, a leading open-source IaC tool, is widely a
Get Started with Building ReactJS and Docker: A Complete Guide
Introduction Docker is a powerful tool that allows developers to create, deploy, and run applications in a portable and scalable way. It uses containerization to encapsulate all the dependencies a
How to CI/CD AWS With Github using Jenkins
Introduction In a previous post, I showed you how to set up Jenkins on an AWS EC2 instance. You can read that post here. In this post, I will sho
Case Studies
Hardening a CI/CD Supply Chain to SLSA Level 3
The question that started this was from an auditor, and it was a fair one: can you prove that the container running in production is the one your pipeline built from the commit you think it was? We ha
Taming a 3am Pager: SLOs and Error Budgets That Stuck
- Reliability
- DevOps
- 29 Aug 2026
- 07 Mins read
A platform team was losing people to burnout, and the cause was the pager. On-call meant a phone that went off day and night with alerts about CPU, memory, and pod restarts, the overwhelming majority
Multi-Region Active-Active for a Payments API
- Architecture
- Cloud Computing
- 16 Aug 2026
- 06 Mins read
A payments API that moves real money had been running comfortably in a single AWS region for years. It was reliable until the day it was not: a regional control-plane incident took the whole service o
Building an Internal Developer Platform on Backstage and GitOps
- DevOps
- Platform Engineering
- 03 Aug 2026
- 09 Mins read
Product teams were spending more time waiting on the platform team than building features. Spinning up a new service meant opening a ticket and waiting for someone to provision a repo, wire up CI, wri
Zero-Downtime PostgreSQL Major-Version Upgrade at Scale
A multi-terabyte PostgreSQL 12 database was reaching end of life, and the business ran around the clock, so the usual answer of "schedule a maintenance window" was off the table. We upgraded it to Pos
Migrating a Monolith to Kubernetes Without a Big-Bang Cutover
- DevOps
- Cloud Native
- 20 Jul 2026
- 07 Mins read
Almost every failed "let's move off the monolith" project shares one detail: the plan was a big-bang cutover. Rewrite in parallel, pick a weekend, flip the switch, and pray. This is the opposite of th
Cheatsheets
Linux Processes
- Operating System
- 12 Sept 2026
A reference for managing Linux processes and services. Covers ps and top for inspection, kill and pkill for signals, nice and renice for priority, cgroups and limits, and systemctl and journalctl for managing and debugging systemd units.
TypeScript
- Programming Language
- 30 Aug 2026
A TypeScript reference covering the type syntax engineers use most, from unions and generics to utility types, modern techniques (satisfies, const type params, template literal types, using), and the TypeScript 7 native compiler.
Python Virtual Environments Cheatsheet
- Python
- 17 Aug 2026
A practical reference for venv, pip, requirements files, pyenv version switching, and pipx for isolated global tools.
GitHub Actions
- DevOps & Tools
- 04 Aug 2026
The workflow YAML you write over and over. Triggers, jobs and steps, secrets, matrix builds, caching, artifacts, and reusable workflows in one reference.
Linux Networking
- DevOps & Tools
- 21 Jul 2026
The commands you reach for to diagnose and manage Linux networks. ip for interfaces and routes, ss for sockets, dig for DNS, traceroute for paths, and tcpdump for packets.
kubectl
- DevOps & Tools
- 27 May 2026
kubectl is the command-line tool for talking to a Kubernetes cluster. Use it to deploy apps, inspect and manage resources, stream logs, and debug running pods.
Code Snippets
Upload Files to AWS S3 with Pre-Signed URLs in Node.js
Routing file uploads through your API server is the default that nobody questions, and it is usually the wrong one. The bytes travel to your compute, sit in memory or a temp file, then travel again to
Multi-Environment Secret Management with HashiCorp Vault
Managing secrets safely across multiple environments with HashiCorp Vault Storing secrets in .env files, hardcoding them, or even using separate secret managers per environment creates security
AWS DynamoDB CRUD Operations in Node.js with the AWS SDK v3
Quick Tip Wrap the low-level DynamoDB client in a DynamoDBDocumentClient so you pass plain JavaScript objects in and get plain objects back, then guard your writes with ConditionExpression an
Python Dataclass Patterns: Slots, Frozen Instances, and Field Validation
Quick Tip Reach for @dataclass(slots=True, frozen=True) with a post_init check and you get a small, immutable, validated value object in about five lines. The Problem The problem
Bash Script Locking: Prevent Concurrent Runs with a PID File
- Bash
- Automation
- 18 Aug 2026
- 03 Mins read
Quick Tip Wrap any script that must not run twice at once in a PID-file lock, and a second copy simply exits instead of corrupting your data. The Problem The Problem Cron does not c
Python Async HTTP Requests with aiohttp: Fetch Multiple URLs Concurrently
Quick Tip Reuse one aiohttp session, fan your requests out with asyncio.gather, and cap them with a semaphore to fetch hundreds of URLs in the time one loop would take. The Problem **The
Dev Tips
Speeding Up CI Pipelines: Caching, Parallelism, and Skipping Unnecessary Work
A slow pipeline does not just waste compute. It changes behaviour. Once feedback takes longer than about ten minutes, people stop waiting for it. They context-switch, batch up changes into bigger pull
Container Image Vulnerability Scanning in CI/CD with Trivy
- DevOps & DevSecOps
- 10 Mar 2026
- 04 Mins read
Why container security matters Where the vulnerabilities hide A container image is one of the largest pieces of untrusted code you ship. Every image you build carries the base OS layer,
Structured Logging & Log Aggregation with ELK Stack
- DevOps & Observability
- 21 Mar 2026
- 05 Mins read
Why centralized logging matters When services fail, where do you look first? In a distributed system, logs scatter across servers, containers and regions. One request might touch five service
Kubernetes Ingress Controllers Explained: Nginx, Traefik, and AWS ALB Compared
- Kubernetes & Containers
- 01 Sept 2026
- 03 Mins read
Why the ingress controller you pick matters Hey, want your cluster to actually serve traffic? Kubernetes gives you the Ingress API, a way to declare "route this host and path to that service.
Terraform Workspaces vs. Directory-Based Environments: What Actually Scales
- Cloud & Infrastructure Automation
- 19 Aug 2026
- 03 Mins read
Why this choice matters Hey, want to stop sweating every prod apply? The way you split dev, staging, and prod in Terraform decides how much damage a single mistake can do. Get it right and a
GitHub Actions Secrets and Environment Variables: Handle Config the Right Way
- DevOps & DevSecOps
- 08 Aug 2026
- 04 Mins read
Why secrets handling matters Most CI leaks are config mistakes, not attacks Hey, want to stop leaking credentials in your pipelines? Most secret leaks in CI are not the result of some cle
Flashcards
AWS Advanced Networking Specialty Flashcards (ANS-C01)
- Aws
- 40 Cards
- ~17 min
- 15 Sept 2026
The ANS-C01 is the AWS exam least forgiving of vocabulary-only knowledge. Most questions describe a working topology, break one thing, and ask which of four plausible components is responsible. Knowin
Linux Foundation Certified System Administrator Flashcards (LFCS)
- Linux
- Certification
- 32 Cards
- ~13 min
- 02 Sept 2026
Spaced-repetition deck for the LFCS exam: essential commands, users and groups, storage, networking, services, and security.
Docker and Container Fundamentals Flashcards
- Containers
- DevOps
- 41 Cards
- ~17 min
- 22 Aug 2026
A spaced-repetition deck covering images, containers, Dockerfiles, volumes, networking, Compose, and registries.
Terraform Associate Flashcards (TA-003)
- Terraform
- Certification
- Devops
- 61 Cards
- ~25 min
- 09 Aug 2026
Full exam coverage for the HashiCorp Certified Terraform Associate (TA-003) exam using spaced repetition. Covers IaC concepts, CLI, HCL, state, modules, backends, and Terraform Cloud.
Kubernetes Administrator Flashcards (CKA)
- Kubernetes
- Certification
- Devops
- 54 Cards
- ~23 min
- 28 Jul 2026
Full exam coverage for the Certified Kubernetes Administrator (CKA) exam using spaced repetition. Covers cluster architecture, workloads, scheduling, networking, storage, security, and troubleshooting.
AWS SysOps Administrator Associate Flashcards (SOA-C02)
- Aws
- Certification
- Devops
- 50 Cards
- ~21 min
- 28 May 2026
Full exam coverage for the AWS Certified SysOps Administrator Associate (SOA-C02) exam using spaced repetition. Covers monitoring, reliability, deployment, security, networking, and cost optimization.
Glossary
Databases & SQL
- Databases
- 38 Terms
- 16 Sept 2026
Most confusion about SQL is vocabulary rather than syntax. People know how to write a join and still get caught by a LEFT JOIN that quietly behaves like an INNER JOIN, because nobody explained that a
Observability & Monitoring
- Devops
- 35 Terms
- 05 Sept 2026
A quick-reference glossary for making sense of system health: the three pillars (metrics, logs, traces), the reliability vocabulary (SLI, SLO, error budget, burn rate), how good alerting works, and th
CI/CD & Automation
- Devops
- 35 Terms
- 23 Aug 2026
A quick-reference glossary of the terms you meet when automating builds, tests, and deployments: pipeline anatomy, test gates, and release strategies like canary and blue-green.
Kubernetes Advanced
- Kubernetes
- Platform
- 39 Terms
- 10 Aug 2026
This glossary covers the advanced Kubernetes terminology platform engineers rely on: scheduling, networking, storage, security, extensibility, and the workload controllers that keep applications runni
Cloud Computing on AWS
This glossary covers the essential Amazon Web Services terms every cloud engineer and architect should know: compute, storage, networking, databases, and the identity controls that keep it all secure.
Networking Fundamentals
- Networking
- Fundamentals
- 47 Terms
- 28 May 2026
This glossary covers the core networking concepts every developer, DevOps engineer, and system administrator should know: how data is layered and addressed, and how it gets routed across the internet.
Incidents
The Admission Gate Denied an Image Built from a Fork
An image built from a fork by a misconfigured pipeline in a sandbox account reached a production cluster and was denied at admission. Under the old setup it would have run, and nobody would have known.
A Regional Control-Plane Failure Took a Payments API Offline
- Sev1
- A few hours
- Reliability
- Architecture
- 08 Sept 2026
A money-movement API ran in one AWS region for years. A regional control-plane incident took it offline for hours with nowhere to fail over to. The fix was idempotency first, then a second region.
Quizzes
Ruby on Rails: Convention Over Configuration
- Ruby
- Web development
- 20 Questions
- ~5 min
- 19 Sept 2026
- Level: Intermediate
Rails is productive because it decided things for you. The router derives a controller and action from a verb and a path, the controller infers its template from its own name, and Active Record infers
PHP & Laravel: Modern Web Development Fundamentals
Ready to check how well you know PHP and Laravel? This quiz runs through routing and middleware, Eloquent relationships and the N+1 trap, migrations and seeders, Blade, and the artisan workflow. Read
C# & .NET: Language and Runtime Fundamentals
Ready to test how well you know C# and the .NET runtime? This quiz walks through the type system, LINQ, async/await, the CLR and garbage collection, and modern features like records and pattern matchi
Spring Boot: Java Application Framework Essentials
- Spring Boot
- Java
- 20 Questions
- ~5 min
- 11 Aug 2026
- Level: Intermediate
Spring Boot removed most of the ceremony from Java backend development, but the framework still does a lot of work you cannot see. This quiz walks through dependency injection, auto-configuration, RES
Java: Core Language & JVM Fundamentals
Java has quietly powered banks, Android, and countless backend systems for decades, and the language keeps evolving with records, sealed classes, and virtual threads. This quiz walks through the core
Rust: Ownership, Borrowing & Memory Safety
- Rust
- Systems Programming
- 20 Questions
- ~5 min
- 28 May 2026
- Level: Intermediate
This quiz tests your grip on the parts of Rust that trip up newcomers and pay off later: ownership and moves, borrowing and lifetimes, traits and generics, pattern matching, error handling with `Resul
Roadmaps
Python Developer Beginner to Expert
- Learning
- All Levels
- 8 Stages
- 41 Topics
- 20 Sept 2026
Python is easy to start and deceptively deep, which produces a common shape of developer: fluent in syntax, productive in a framework, and unsure what happens when the code meets real traffic. This ro
Node.js Developer Beginner to Expert
- Backend development
- All Levels
- 13 Stages
- 31 Topics
- 07 Sept 2026
Node.js Developer Beginner to Expert This roadmap takes you from JavaScript foundations and the event loop through building APIs, working with databases, streams, testing, and security, and on to r
React Developer Beginner to Expert
- Web development
- All Levels
- 13 Stages
- 31 Topics
- 25 Aug 2026
React Developer Beginner to Expert This roadmap takes you from JavaScript prerequisites through JSX, hooks, and state management, and on to data fetching, meta-frameworks, performance, and testing.
Full-Stack Developer Beginner to Expert
- Web development
- All Levels
- 18 Stages
- 50 Topics
- 12 Aug 2026
Full-Stack Developer Beginner to Expert This roadmap walks you from your first web page to shipping and operating a complete production application. Work the stages in order. Build the frontend fun
Backend Developer Beginner to Expert
- Web development
- All Levels
- 17 Stages
- 57 Topics
- 02 Aug 2026
Backend Developer Beginner to Expert This roadmap walks you from your first server-side program to designing scalable, secure systems. Work through the stages in order. Nail a language, the command
Frontend Developer Beginner to Expert
- Web development
- All Levels
- 18 Stages
- 81 Topics
- 28 May 2026
Frontend Developer Beginner to Expert This roadmap walks you from absolute beginner to a strong, hireable frontend engineer. Work through the stages in order. The early ones build the mental model