Quickstart: Create a serverless app with Azure Functions and SignalR Service using JavaScript
Article
In this article, you use Azure SignalR Service, Azure Functions, and JavaScript to build a serverless application to broadcast messages to clients.
Important
Raw connection strings appear in this article for demonstration purposes only.
A connection string includes the authorization information required for your application to access Azure SignalR Service. The access key inside the connection string is similar to a root password for your service. In production environments, always protect your access keys. Use Azure Key Vault to manage and rotate your keys securely and secure your connection string using Microsoft Entra ID and authorize access with Microsoft Entra ID.
Avoid distributing access keys to other users, hard-coding them, or saving them anywhere in plain text that is accessible to others. Rotate your keys if you believe they may have been compromised.
Prerequisites
This quickstart can be run on macOS, Windows, or Linux.
Optionally, you can use the Azure CLI to create an Azure SignalR Service instance.
Create an Azure SignalR Service instance
In this section, you create a basic Azure SignalR instance to use for your app. The following steps use the Azure portal to create a new instance, but you can also use the Azure CLI. For more information, see the az signalr create command in the Azure SignalR Service CLI Reference.
In the upper-left side of the page, select + Create a resource.
On the Create a resource page, in the Search services and marketplace text box, enter signalr and then select SignalR Service from the list.
On the SignalR Service page, select Create.
On the Basics tab, you enter the essential information for your new SignalR Service instance. Enter the following values:
Field
Suggested Value
Description
Subscription
Choose your subscription
Select the subscription you want to use to create a new SignalR Service instance.
Resource group
Create a resource group named SignalRTestResources
Select or create a resource group for your SignalR resource. It's useful to create a new resource group for this tutorial instead of using an existing resource group. To free resources after completing the tutorial, delete the resource group.
Deleting a resource group also deletes all of the resources that belong to the group. This action can't be undone. Before you delete a resource group, make certain that it doesn't contain resources you want to keep.
Enter a unique resource name to use for the SignalR resource. If testsignalr is already taken in your region, add a digit or character until the name is unique.
The name must be a string of 1 to 63 characters and contain only numbers, letters, and the hyphen (-) character. The name can't start or end with the hyphen character, and consecutive hyphen characters aren't valid.
Region
Choose your region
Select the appropriate region for your new SignalR Service instance.
Select Change and then choose Free (Dev/Test Only). Choose Select to confirm your choice of pricing tier.
Azure SignalR Service has three pricing tiers: Free, Standard, and Premium. Tutorials use the Free tier, unless noted otherwise in the prerequisites.
For more information about the functionality differences between tiers and pricing, see Azure SignalR Service pricing
Service mode
Choose the appropriate service mode
Use Default when you host the SignalR hub logic in your web apps and use SignalR service as a proxy. Use Serverless when you use Serverless technologies such as Azure Functions to host the SignalR hub logic.
Classic mode is only for backward compatibility and isn't recommended to use.
After you initialize a project, you need to create functions. This project requires three functions:
index: Hosts a web page for a client.
negotiate: Allows a client to get an access token.
broadcast: Uses a time trigger to periodically broadcast messages to all clients.
When you run the func new command from the root directory of the project, the Azure Functions Core Tools creates the function source files storing them in a folder with the function name. You edit the files as necessary replacing the default code with the app code.
Create the index function
Run the following command to create the index function.
Bash
func new -n index -t HttpTrigger
Edit src/functions/httpTrigger.js and replace the contents with the following json code:
Run the Azure Function app in the local environment:
Bash
func start
After the Azure Function is running locally, go to http://localhost:7071/api/index. The page displays the current star count for the GitHub Azure/azure-signalr repository. When you star or unstar the repository in GitHub, you'll see the refreshed count every few seconds.
If you're not going to continue to use this app, delete all resources created by this quickstart with the following steps so you don't incur any charges:
In the Azure portal, select Resource groups on the far left, and then select the resource group you created. Alternatively, you may use the search box to find the resource group by its name.
In the window that opens, select the resource group, and then click Delete resource group.
In the new window, type the name of the resource group to delete, and then click Delete.
Sample code
You can get all code used in the article from GitHub repository:
In this quickstart, you built and ran a real-time serverless application in localhost. Next, learn more about how to bi-directional communicating between clients and Azure Function with SignalR Service.
Change a JavaScript web app update mechanism from polling to real-time push-based architecture with SignalR Service, Azure Cosmos DB and Azure Functions. Use Vue.js and JavaScript to use SignalR using Visual Studio Code.
Build end-to-end solutions in Microsoft Azure to create Azure Functions, implement and manage web apps, develop solutions utilizing Azure storage, and more.