Azure

Make your Service Bus message handlers idempotent

Azure Service Bus delivers every message at least once, and duplicates can arrive at the same moment. Here's how to make handling the same message twice harmless, even when two copies race.

How retries really work with the Service Bus trigger

When a Service Bus-triggered function throws, the message is retried immediately, ten times in a row, and then dead-lettered. If you need a delay between attempts, you have to build it.

Ship code dark with feature flags

Feature flags separate deploying code from releasing it. With Azure App Configuration, you can turn a feature on for 10% of users, or off in an emergency, without a deployment.

Zero-downtime deployments with slots

Deploying straight to production means a cold start and no quick way back. Deployment slots let you deploy, warm up and check a release first, then swap it live in seconds.

Route messages with Service Bus topic filters

With a topic, every subscription gets every message by default. Filters let each consumer receive only what it needs, without the publisher knowing who's listening.

Share blobs with user delegation SAS tokens

A SAS token signed with the storage account key can't be revoked without rotating the key. A user delegation SAS is signed with Entra ID credentials, expires sooner and fits with managed identity.

Fan-out and fan-in with Durable Functions

Processing 5,000 records one after another takes too long, and running them all at once in one function times out. Durable Functions runs them in parallel and collects the results.

Health checks that tell the truth

A health endpoint that always returns 200 doesn't help anyone. Separate "is the process alive" from "can it do its job", and let App Service act on the answer.

Moving Azure Functions to the isolated worker model

Support for the in-process model ends in November 2026. The isolated worker model is where new .NET versions and features land, and the move is mostly mechanical.

Structured logging that you can actually query

A log message built with string interpolation is just text. A message template turns every value into a field you can filter and chart in Application Insights.

Don't ignore your dead-letter queue

Every Service Bus queue and subscription has a dead-letter queue. Messages that land there are silently waiting for someone to notice. Here's how to watch it, inspect it and replay it.

Key Vault references in App Service and Functions

Keep secrets in Key Vault without changing a line of code. App settings can point at a secret, and your app reads it like any other setting.

Use managed identity instead of connection strings

Connection strings with keys end up in config files, pipelines and screenshots. Managed identity lets your Azure app authenticate with no secret at all.