Long-form engineering notes on distributed systems, multi-tenant architecture, delivery guarantees, AI pipelines and release automation.https://musfiqdehan.comen-us© 2026 Md. Musfiqur Rahamanhttps://musfiqdehan.com/og/blog.pnghttps://musfiqdehan.com/https://musfiqdehan.com/blog/zero-downtime-blue-green-traefikhttps://musfiqdehan.com/blog/zero-downtime-blue-green-traefikA routine deploy costs about a minute of failed requests, because "update" quietly means stop-then-start. Here is the pipeline that ships to a single server without a customer ever seeing an error - no Kubernetes, no second load balancer, and a rollback that is the same path as the deploy.Thu, 30 Jul 2026 00:00:00 GMTDockerTraefikGitHub ActionsCI/CDZero DowntimeDeploymentmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/offline-first-pos-tauri-sync-outboxhttps://musfiqdehan.com/blog/offline-first-pos-tauri-sync-outboxA till that stops working when the internet does is a till that loses money. Here is the contract that lets a desktop point of sale keep selling through an outage and reconcile exactly once when the connection returns - without ever charging a customer twice or losing a sale from the books.Wed, 29 Jul 2026 00:00:00 GMTTauriReactSQLiteDjangoOffline-FirstIdempotencyPostgreSQLmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/decomposing-a-monolith-without-a-rewritehttps://musfiqdehan.com/blog/decomposing-a-monolith-without-a-rewriteSplitting a large codebase is usually sold as a rewrite and delivered as a disaster. Here is how to do it piece by piece while the product keeps shipping to customers - plus an honest account of what independent deployment actually costs you in return.Wed, 08 Jul 2026 00:00:00 GMTArchitectureMicroservicesDjangoRefactoringLeadershipDockermusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/lease-based-url-frontier-postgreshttps://musfiqdehan.com/blog/lease-based-url-frontier-postgresHow to get a crash-safe job queue out of the database you already run, instead of adding another service to operate, monitor and be woken up by. Workers claim jobs on a timed lease, so a machine dying halfway through costs minutes of delay rather than lost work.Thu, 18 Jun 2026 00:00:00 GMTPostgreSQLDistributed SystemsQueuesPythonConcurrencymusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/four-stage-deduplication-pipelinehttps://musfiqdehan.com/blog/four-stage-deduplication-pipelineThe expensive way to find duplicates is to compare everything using AI. Ordering the checks cheapest-first removes roughly nine in ten duplicates with a simple lookup and saves the costly comparison for the small remainder - the same quality of result, at a fraction of the running cost.Wed, 27 May 2026 00:00:00 GMTDeduplicationSimHashEmbeddingspgvectorMultilingual NLPPostgreSQLmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/at-least-once-redis-streamshttps://musfiqdehan.com/blog/at-least-once-redis-streamsRetries are what stop a system losing work - and what make it do the same work twice. This is how to get the reliability without the duplicates: handlers safe to re-run, retries that back off, a dead-letter queue you can actually triage, and recovery for messages a crashed worker left behind.Wed, 06 May 2026 00:00:00 GMTRedisStreamsReliabilityPythonIdempotencyQueuesmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/schema-per-tenant-django-multi-tenancyhttps://musfiqdehan.com/blog/schema-per-tenant-django-multi-tenancySharing one database between customers is one forgotten filter away from showing one client another client's data. Giving each customer their own separate space moves that safety from something developers must remember into something the database enforces - and here is exactly what it costs.Tue, 14 Apr 2026 00:00:00 GMTDjangoPostgreSQLMulti-TenancySaaSRBACArchitecturemusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/holding-10k-dau-before-you-scale-uphttps://musfiqdehan.com/blog/holding-10k-dau-before-you-scale-upA platform went from a few hundred to 10,000+ daily users without a bigger server. Four fixes did all the work - and buying hardware first would have hidden every one of them while the monthly bill kept growing.Thu, 19 Mar 2026 00:00:00 GMTPostgreSQLPgBouncerDjangoPerformanceRedisDeploymentmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/one-api-three-clientshttps://musfiqdehan.com/blog/one-api-three-clientsWhat changes when one backend must serve a web dashboard, a phone app, and a fingerprint terminal that cannot be updated, cannot be trusted about time and is usually offline. The most awkward client turned out to be the best specification the API ever got.Tue, 24 Feb 2026 00:00:00 GMTAPI DesignDjangoReact NativeIoTOffline SyncWebSocketmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/let-the-agent-propose-not-writehttps://musfiqdehan.com/blog/let-the-agent-propose-not-writeThe single boundary that separates an AI feature you can safely point at real customer data from a demo you cannot: the model proposes, the application decides. Plus validated output, provider failover and cost tracking treated as engineering problems rather than prompting problems.Thu, 29 Jan 2026 00:00:00 GMTLLMAgentsGeminiLangChainReliabilityArchitecturemusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/tag-driven-python-releaseshttps://musfiqdehan.com/blog/tag-driven-python-releasesEvery manual step in a release is a step somebody skips at 11pm - and the skipped step is the one customers find. How a forty-minute checklist became one command, with version numbers, release notes, builds and publishing all produced by automation.Thu, 11 Dec 2025 00:00:00 GMTPythonPoetryGitHub ActionsCI/CDOpen SourceVersioningmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)