从Azure函数提供HTML文件时出错

Question

I am trying to open, read and return an HTML files using Azure functions. I am developing locally and the logs says that the function executed successfully however on the browser I am getting 500 internal server error. Am I doing something wrong in here?

const fs = require('fs');
const path = require('path');
const mime = require('../node_modules/mime-types');
module.exports = function (context, req) {
    const staticFilesFolder = 'www/build/';
    const defaultPage = 'index.html';
    getFile(context, req.query.file);
    function getFile(context, file) {
        const homeLocation = process.env["HOME"];
        if(!file || file == null || file === undefined){
            context.done(null,{status:200,body:"<h1>Define a file</h1>",headers:{
                "Content-Type":" text/html; charset=utf-8"
            }});
        }
        fs.readFile(path.resolve(path.join(homeLocation, staticFilesFolder, file)),
             (err, htmlContent) => {
                if (err) {
                    getFile(context, "404.html");
                }
                else {
                    const res = {
                        status: 200,
                        body: htmlContent,
                        headers:{
                            "Content-Type": mime.lookup(path.join(homeLocation, staticFilesFolder, file))
                        }

                    }
                    context.done(null,res);
                }
            })
    }

};

Note I am sure that 404.html exists and index.html exists. When I log the contents of htmlContent it is giving the correct output.

functions.json

{
  "disabled": false,
  "bindings": [
    {
      "authLevel": "anonymous",
      "type": "httpTrigger",
      "direction": "in",
      "methods":["get"],
      "route":"home",
      "name": "req"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    }
  ]
}

Response on Chrome

If I removed "Content-Length" header the status code changes to 406.

Update 1 The code seems to be running normally on Azure Portal but it is not working when running it locally.

Answer 1

It looks like you are combining two methods of returning data from an http triggered function( context.res and context.done() ): https://docs.microsoft.com/en-us/azure/azure-functions/functions-reference-node#accessing-the-request-and-response

Since you are using context.res , try removing context.done();

Answer 2

You are making an incorrect use of context.res , you shouldn't be overwriting it but instead leveraging the methods provided by the Response class provided in the Azure NodeJS worker. If you are using using VSCode you'll get intellisense for these methods. Otherwise see: https://github.com/Azure/azure-functions-nodejs-worker/blob/dev/src/http/Response.ts

Your code should look something like this instead.

context.res.setHeader('content-type', 'text/html; charset=utf-8')
context.res.raw(htmlContent)

Using context.res.raw or context.res.send will already perform the context.done call for you.

Make sure you use content-type=text/html; charset-utf8 content-type=text/html; charset-utf8 instead of content-type=text/html or you'll trigger an issue with the returned content-type. Instead of returning content-type=text/html you end up getting content-type=text/plain which will fail to render your html.

Addressed on: https://github.com/Azure/azure-webjobs-sdk-script/issues/2053