How to download a json file to Blob storage container using keys or connection string

Question

Dear Microsoft do you have any tutorial on how to download a json file to Blob storage container using Access keys or connection string from the storage account instead of Shared access tokens. I am having a hard time updating storage account(dev, UAT and Prod) and expiring date.

Answer 1

Hello Gabe,

Thank you for posting your query here!

I understand that you are trying to download a json file from Blob storage container using Access keys or connection string from the storage account instead of Shared access tokens.

Here is a JavaScript code that uses the @azure/storage-blob library to download a blob from Azure Blob Storage. The code provided is using a connection string for authentication.

const { BlobServiceClient } = require('@azure/storage-blob');
const fs = require("fs");

const connectionString = "<your-connection-string>"; // Replace with your actual connection string
const containerName = "<your-container-name>"; // Replace with your actual container name
const blobName = "<your-blob-name>"; // Replace with your actual blob name

const blobServiceClient = BlobServiceClient.fromConnectionString(connectionString);
const containerClient = blobServiceClient.getContainerClient(containerName);
const blobClient = containerClient.getBlobClient(blobName);

// Download the blob
const downloadBlockBlobResponse = await blobClient.download();

// Convert the readable stream to a string
const downloadedContent = await streamToString(downloadBlockBlobResponse.readableStreamBody);

console.log("Downloaded blob content:", downloadedContent);

// Function to convert a readable stream to a string
async function streamToString(readableStream) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    readableStream.on("data", (data) => {
      chunks.push(data.toString());
    });
    readableStream.on("end", () => {
      resolve(chunks.join(""));
    });
    readableStream.on("error", reject);
  });
}

Please note that using keys in code is not considered a recommended practice for security reasons. It's generally better to use Azure Managed Identities or Shared Access Signatures (SAS) for better security and easier rotation. If possible, consider using Azure Key Vault to store and manage secrets securely.

As you are facing issue with SAS token due to expiry, I would recommend checking the following article to configure SAS expiration policy: https://learn.microsoft.com/en-us/azure/storage/common/sas-expiration-policy?tabs=azure-portal#how-to-configure-a-sas-expiration-policy

You can also upload and download data between your local machine and Azure Storage accounts with the help of Azure Storage Explorer, you can connect it to Storage accounts using connection strings: https://learn.microsoft.com/en-us/azure/vs-azure-tools-storage-manage-with-storage-explorer?tabs=windows#account-name-and-key

Please let us know if you have any further queries. I’m happy to assist you further.

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Answer 2

You don't mention a preferred language but here is an example in C# to both upload and download a file to/from blob storage. It uses the Azure.Storage.Blob NuGet SDK and dynamically builds the connection string with the storage account name and account key.
Ideally, you would keep your key secure in an Azure KeyVault or secured configuration file, but this should get you started.

using Azure.Storage.Blobs;
using System.IO;
using System.Threading.Tasks;

public class BlobStorageService
{
    private string storageAccountName = "<Your Storage Account Name>";
    private string storageAccountKey = "<Your Storage Account Key>";
    private string containerName = "<Your Container Name>";

    public async Task DownloadFromBlob(string fileName)
    {
        string connectionString = $"DefaultEndpointsProtocol=https;AccountName={storageAccountName};AccountKey={storageAccountKey};EndpointSuffix=core.windows.net";
        var blobClient = new BlobClient(connectionString, containerName, fileName);
        BlobDownloadInfo download = await blobClient.DownloadAsync();

        using (FileStream file = File.OpenWrite(fileName))
        {
            await download.Content.CopyToAsync(file);
        }
    }

    public async Task UploadToBlob(string filePath, string blobName)
    {
        string connectionString = $"DefaultEndpointsProtocol=https;AccountName={storageAccountName};AccountKey={storageAccountKey};EndpointSuffix=core.windows.net";
        var blobClient = new BlobClient(connectionString, containerName, blobName);

        using (FileStream file = File.OpenRead(filePath))
        {
            await blobClient.UploadAsync(file, true);
        }
    }
}