Triggers and Bindings

Triggers and bindings are the mechanism that connects Azure Functions to external services. A trigger defines how a function is invoked. Bindings provide a declarative way to read from and write to external data sources without writing boilerplate connection code. Understanding triggers and bindings is essential to building effective serverless applications on Azure.

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What is a Trigger?

A trigger is the event that causes a function to execute. Every function must have exactly one trigger. The trigger defines:

• What event starts the function (HTTP request, queue message, timer, blob upload, etc.)
• The payload delivered to the function (the request body, message content, blob data)
• The metadata about the event (message ID, enqueue time, blob path)

Common triggers: