Daily Dejavu — Tutorials That Stick for Real Developers

Hands-on backend, database, and DevOps tutorials written by a security-minded engineer. No copy-paste fluff — just field-tested patterns you won't forget.

GitHub Actions workflow showing test build stage and deploy stages

DevOps & Infrastructure

How to Build a Production CI/CD Pipeline with GitHub Actions — Staging, Secrets, and Rollback

Your deploy process is SSH into server, git pull, pray. Here's how to build a real CI/CD pipeline with GitHub Actions — automated tests, staging deploys, production gates, and rollback that works.

banditz

Apr 20, 2026

Diagram showing Docker bridge host and overlay network modes

DevOps & Infrastructure

Docker Networking Explained — Bridge vs Host vs Overlay and When to Use Each

Your containers can't talk to each other. Or they can, but only by IP and not by name. Or port mapping isn't working. Docker networking has six modes and most people only understand one of them.

banditz

Apr 20, 2026

Diagram showing token bucket rate limiting algorithm with request flow

Backend Engineering

How to Implement API Rate Limiting — Token Bucket, Sliding Window, and the Edge Cases Nobody Warns You About

Your API has no rate limiting and someone just hit it 50,000 times in a minute. Here's how to pick the right algorithm, implement it with Redis, and handle the edge cases that break naive implementations.

banditz

Apr 17, 2026

Diagram showing JWT token flow between client and server

Backend Engineering

How to Implement JWT Authentication Properly — Access Tokens, Refresh Tokens, and Common Mistakes

Most JWT tutorials store tokens in localStorage and skip refresh flow. Here's how to implement JWT auth that actually holds up in production — proper token pairs, secure storage, and revocation.

banditz

Jan 9, 2026

MySQL SHOW REPLICA STATUS showing high Seconds_Behind_Master

Database Systems

How to Diagnose and Fix MySQL Replication Lag

Your replica is 300 seconds behind. Reads return stale data and users see ghost records. Here's how to find the cause and fix it without breaking replication.

banditz

Jan 7, 2026

Linux terminal showing find command results for SUID files

Cyber Security

How to Audit Linux File Permissions and Find Security Holes

Someone ran chmod 777 to fix a permissions error. Now your server has a gaping hole. Here's how to audit file permissions and find dangerous misconfigurations before attackers do.

banditz

Jan 5, 2026

Linux terminal showing auth.log with failed SSH login attempts and fail2ban blocking IPs

Cyber Security

How to Harden SSH and Stop Brute Force Attacks on Linux Servers — Read the Logs Before You Lock the Door

Every Linux server with SSH exposed to the internet gets hammered by brute force bots within hours of going live. Most admins just change the port and call it a day. But if you actually read /var/log/auth.log, you'd see that the bots adapt — they rotate usernames.

banditz

Jan 3, 2026

PostgreSQL EXPLAIN ANALYZE output showing sequential scan bottleneck with actual time highlighted

Database Systems

How to Find and Fix Slow Queries in PostgreSQL — Read EXPLAIN ANALYZE Before You Add Random Indexes

Your API endpoint takes 4 seconds to respond. Your dashboard loads like it's 2003. Someone suggests "just add an index" without even looking at the query plan. Stop. The problem might not be a missing index at all — it could be stale statistics, a bad join order, an ORM generating garbage SQL.

banditz

Jan 1, 2026