HTTP trigger bindings

This article explains how to configure and use the HTTP trigger binding in Azure Functions.

Overview

The HTTP trigger allows your function to be invoked via an HTTP request. It's one of the most common triggers, enabling you to build serverless APIs, webhooks, and more.

Configuration

The HTTP trigger is configured in your function's function.json file. Here's a basic example:

{
  "scriptFile": "run.cs",
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "methods": [
        "get",
        "post"
      ]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    }
  ]
}

Binding Properties

The HTTP trigger binding has the following properties:

Request and Response

When the HTTP trigger is invoked:

• The incoming HTTP request is bound to the parameter specified by the name property in your function code.
• Your function's return value or the parameter bound with direction: "out" and type: "http" is used to construct the HTTP response.

Accessing Request Properties

You can access various properties of the incoming HTTP request, such as:

• req.method: The HTTP method of the request.
• req.headers: A dictionary of request headers.
• req.query: A dictionary of query parameters.
• req.body: The request body (parsed as JSON if the Content-Type is application/json).
• req.params: URL route parameters (if route is used).

Creating a Response

You can create an HTTP response by returning an object from your function or by setting properties on the output binding parameter:

• statuscode: The HTTP status code.
• body: The response body.
• headers: A dictionary of response headers.

Example (Node.js)

Here's a Node.js example of an HTTP-triggered function:

module.exports = async function (context, req) {
    context.log('JavaScript HTTP trigger function processed a request.');

    const name = (req.query.name || (req.body && req.body.name));
    const responseMessage = name
        ? "Hello, " + name + "!"
        : "This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response.";

    context.res = {
        status: 200,
        body: responseMessage,
        headers: {
            'Content-Type': 'application/json'
        }
    };
};

Example (C#)

Here's a C# example:

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;

public static class HttpExample
{
    [FunctionName("HttpExample")]
    public static async Task Run(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
        ILogger log)
    {
        log.LogInformation("C# HTTP trigger function processed a request.");

        string name = req.Query["name"];

        string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
        dynamic data = JsonConvert.DeserializeObject(requestBody);
        name = name ?? data?.name;

        string responseMessage = string.IsNullOrEmpty(name)
            ? "This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response."
            : $"Hello, {name}!";

        return new OkObjectResult(responseMessage);
    }
}

Next Steps

• Learn about HTTP output bindings.
• Create your first HTTP-triggered function.