DevSaaS Blog
Practical DevOps guides, infrastructure troubleshooting, and engineering deep-dives.
fix PRECONDITION_FAILED inequivalent arg x-dead-letter-exchange without deleting queue
Fix PRECONDITION_FAILED on x-dead-letter-exchange with a zero-downtime shadow queue migration, no deleted messages, no dropped consumers.
docker compose depends_on condition service_healthy not working first run
Why docker compose depends_on condition service_healthy fails only on first run with fresh volumes, and how to fix the Postgres init restart race condition.
unacked messages no consumers attached rabbitmq
Queue shows unacked messages with zero consumers in RabbitMQ? Learn how to find the dead connection holding them hostage and force a requeue.
kubernetes service not distributing traffic evenly between pods
Why Kubernetes Service traffic skews to one pod even with healthy endpoints: iptables/IPVS connection pinning, conntrack, and fixes.
ImagePullBackOff private registry imagePullSecrets not working
ImagePullBackOff still happening despite correct imagePullSecrets? Diagnose token expiry, SA misconfig, node-level auth, and registry rate limits.
pod crashloopbackoff but logs are empty
CrashLoopBackOff with empty logs and no previous container to inspect? Here's how to actually find the root cause instead of guessing.
kubernetes pod crashloopbackoff but no logs available
Empty logs during CrashLoopBackOff? Learn to decode exit codes, use kubectl logs --previous, and debug containers to find the real cause fast.
how to invalidate a single JWT without blacklist
Learn how to invalidate a single JWT without a blacklist using short TTLs, refresh token rotation, and risk-based revocation tiers.
github actions cache not found key isn't matching branch
Your GitHub Actions cache works on main but shows 'not found' on PR branches? Learn the branch scoping rules causing it and how to fix it.
how to invalidate a JWT before it expires without a database
Learn how to invalidate a JWT before expiry without a database, using real math to compare lookup cost against exposure window per your traffic.
docker container exits with code 0 but not error
Docker container exits with code 0 but you expected it to keep running? Learn what exit codes 0, 1, 137, and 143 actually mean and how to fix each one.
how to invalidate JWT without database lookup on every request
Learn to invalidate JWT tokens without a database lookup per request using Redis TTL caches, token epochs, and short-lived refresh pairs.
refresh token reuse detection without storing all tokens in database
Detect refresh token reuse in Redis without storing every issued token. Learn token family design, atomic Lua swaps, and race condition fixes.
how to implement distributed rate limiting across multiple api servers with redis
Learn how to fix race conditions, clock drift, and atomicity bugs when building distributed rate limiting across multiple API servers with Redis.
how to revoke a jwt before it expires
Learn how to revoke a JWT before it expires using refresh token rotation, Redis denylists, and versioned tokens — with real tradeoffs for each.
should I use multi-stage Dockerfile or separate Dockerfiles
Multi-stage Dockerfile vs separate Dockerfiles? A practical decision framework covering CI/CD caching, shared base stages, and team workflow tradeoffs.
kubernetes hpa not scaling down after load decreases
Kubernetes HPA not scaling down after load decreases? Learn to diagnose stale metrics, stabilization windows, and metrics-server lag with real fixes.
kafka consumer lag increasing despite adding more consumers
Kafka consumer lag still climbing after scaling out? Learn why more consumers don't fix lag and how to convert lag into a time-to-drain metric.
how to secure terraform state file locking in AWS CI/CD pipeline
Learn how to diagnose and fix Terraform state lock failures in AWS CI/CD pipelines, including stuck DynamoDB locks and safe force-unlock steps.
how to improve elasticsearch index write rate on high IOPS EBS nodes
Diagnose real Elasticsearch write bottlenecks on EBS-backed nodes by correlating disk IOPS, CPU, and thread pool rejections before touching bulk size.
how to set up prometheus with grafana docker-compose not showing metrics
Prometheus running, Grafana connected, but no metrics? Fix the docker-compose networking and datasource URL mistakes causing this.
how to structure github actions ci/cd pipeline with no devops experience
Learn how to structure a GitHub Actions CI/CD pipeline with no DevOps experience—covering secrets, approval gates, and rollback strategy.
rabbitmq priority queue vs multiple queues pattern
RabbitMQ priority queue vs multiple queues: compare starvation risk, memory overhead, and consumer patterns to pick the right approach.
redis caching strategy for paginated and filtered api results
Learn a practical Redis caching strategy for paginated and filtered API results, covering composite key design, TTL tuning, and invalidation.
pgbouncer vs application-level connection pooling best practices
A decision framework for PgBouncer vs application-level pooling: how max_connections, PgBouncer modes, and driver pools interact and conflict.
prestashop docker development environment with git for custom modules and themes
Learn how to configure Docker volumes and .gitignore rules so PrestaShop module and theme code survives container rebuilds without data loss.
node.js memory leak detection production
Skip the heap snapshot rabbit hole. Learn the fastest Node.js memory leak detection production check: EventEmitter listener audits.
nginx 502 bad gateway docker
Fix nginx 502 bad gateway in Docker by separating host-level networking faults from Docker network isolation with this diagnostic decision tree.