GitHub - Azure-Samples/azure-functions-nodejs-stream: Sample app to demonstrate HTTP streams on Azure Functions. (original) (raw)

Azure Functions Node.js Stream Sample

The app in this repo demonstrates the new Node.js HTTP streams feature on Azure Functions. It streams a large file (96mb by default) named temp/input.txt to a file temp/output.txt and logs the progress. This app has http streams turned on by default, but you can change this (and other settings) by modifying the src/constants.ts file.

Prerequsites

• Version 4.0.5530 of Azure Functions Core Tools
• Node.js v18+

Run the app

1. Add a local.settings.json file with the following contents:
   {
   "IsEncrypted": false,
   "Values": {
   "AzureWebJobsStorage": "",
   "FUNCTIONS_WORKER_RUNTIME": "node",
   "FUNCTIONS_REQUEST_BODY_SIZE_LIMIT": "4294967296"
   }
   }
2. Run npm install.
3. Run npm start. This will build the app, create the large input file, and start the app.
4. Leave the previous terminal running and open a new terminal to execute a function.
   • If you want to simulate streaming a request, run npm run streamRequest.
   • If you want to simulate streaming a response, run npm run streamResponse.
5. You should see progress in the console as the file is processed. It happens fast for a 96mb file, but as long as you see a chunk count greater than 1, you know your data was streamed.

App contents

• src/functions/*: The actual functions for your app
• src/scripts/*: Scripts used to create the large file and send requests to Azure Functions
• src/constants.ts: A file with several settings that you can change to modify the behavior of the app.

Next steps

We recommend you play around with this app to really get a feel for the feature!

1. Follow the steps above to run your app.
2. Open a new terminal and run npm watch. This will ensure your running app is updated every time you save a file.
3. Modify a setting in src/constants.ts, run the scripts mentioned above to simulate streaming a request or response, and see what happens!
   • enableHttpStream: Set this to false to turn the stream feature off. In general, you will notice slower performance and more errors with this feature off.
   • sendRequestInChunks: Set this to false to simulate different ways of sending a request to your app. The new streams feature will work regardless of how the request is sent, but without the new feature your app can fail in a variety of ways.
   • inputFileSize: Set this to a higher value to test the limits of your app. Each time you change this value, you will need to run npm run createInputFile to re-generate the input file with a different size.