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Azure Functions Extensions

Azure Functions extensions allow you to integrate your functions with a variety of services and add custom functionality. This page provides an overview and guidance on how to use popular extensions.

What are Azure Functions Extensions?

Extensions for Azure Functions are typically implemented as NuGet packages or npm packages, depending on the language. They provide pre-built connectors and logic that simplify common integration scenarios.

Popular Extensions

Azure Blob Storage Binding

This binding allows your functions to easily read from and write to Azure Blob Storage. You can configure it as an input or output binding.

{
  "bindings": [
    {
      "name": "myBlob",
      "type": "blob",
      "direction": "in",
      "path": "input/{name}.txt",
      "connection": "AzureWebJobsStorage"
    },
    {
      "name": "outputBlob",
      "type": "blob",
      "direction": "out",
      "path": "output/{name}.txt",
      "connection": "AzureWebJobsStorage"
    }
  ]
}
                

Azure Cosmos DB Binding

Integrate with Azure Cosmos DB to read and write documents. This binding supports various operations like creating, reading, and querying documents.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;

public static class CosmosDbFunction
{
    [FunctionName("GetCosmosDocuments")]
    public static void Run(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
        [CosmosDB(
            databaseName: "mydatabase",
            collectionName: "mycollection",
            ConnectionStringSetting = "CosmosDBConnection",
            Id = "{Query.id}",
            PartitionKey = "{Query.partitionKey}")] MyDocument inputDocument,
        ILogger log)
    {
        if (inputDocument != null)
        {
            log.LogInformation($"Document found: {inputDocument.Id}");
            // Process the document
        }
        else
        {
            log.LogInformation("No document found.");
        }
    }

    public class MyDocument
    {
        public string Id { get; set; }
        public string Name { get; set; }
        // Other properties
    }
}
                

Azure Service Bus Binding

Connect to Azure Service Bus queues and topics to send and receive messages. This is crucial for building event-driven architectures.

module.exports = async function (context, mySbMsg) {
    context.log('JavaScript ServiceBus queue trigger function processed message', mySbMsg);
    // Process the message
};
                

Custom Extensions

You can also develop your own custom extensions to abstract complex logic or integrate with proprietary services. This typically involves creating a custom binding provider.

Key Concepts

• Bindings: Define how your function connects to external data and services.
• Triggers: Determine what causes your function to execute.
• Input/Output Bindings: Specify data flowing into or out of your function.

Further Reading

For detailed information on specific bindings and how to configure them, please refer to the official Azure Functions documentation for each service.

API Reference

The following table provides a quick reference to some common extension types.