Setting Container Cors Rules in Azure

This week I’m busy upgrading some legacy code to the latest version of the Azure SDKs. This code is so old it was using packages like WindowsAzure.Storage. Over the years this library has evolved significantly and is now part of the Azure.Storage.Blobs package. What this code I was updating was doing was setting the CORS rules on a blob container. These days I think I would solve this problem using Terraform and set the blob properties directly on the container. But since I was already in the code I figured I would just update it there.

So what we want is to allow anybody to link into these and download them with a GET

using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;
...
var bsp = new BlobServiceProperties { HourMetrics = null, MinuteMetrics = null, Logging = null };
bsp.Cors.Add(new BlobCorsRule
{
    AllowedHeaders =  "*",
    AllowedMethods = "GET",
    AllowedOrigins = "*",
    ExposedHeaders = "*",
    MaxAgeInSeconds = 60 * 30 // 30 minutes
});

// from a nifty little T4 template
var connectionString = new ConnectionStrings().StorageConnectionString;
BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);
blobServiceClient.SetProperties(bsp);

Again, in hindsight I feel like these rules are overly permissive and I would probably want to lock them down a bit more.