Re-use service instances by Implementing Dependency Injection in Azure Functions

This article explains how to implement Dependency Injection (DI) in Azure Functions to reuse service instances across multiple function executions. It describes a real-world scenario where a Function App with 8 functions processes hundreds of millions of queue items monthly. By injecting services like custom loggers, database connections, and APIs at startup instead of creating new instances per execution, the author reduced average execution time from 2500ms to 1800ms (a 700ms savings per run). The article includes performance comparisons, scaling benefits, and cost savings, along with references to Microsoft Docs for implementation details.