Azure-WebAPI-blob-storage

Author(s): Dave Voyles | @DaveVoyles

URL: www.DaveVoyles.com

Access Azure Blob Storage from a .NET Web API app.

About

Manipulate Azure Blob Storage from a .NET Web API app. Simply host this project in Azure App Service.

Instructions

You'll need to set the conection string to your Azure Blob Storage Account to store any content and use this function.

If testing locally...

You'll need to change the connection strings in the web.config file:

 <connectionStrings>
    <add name="ConnString"  connectionString="DefaultEndpointsProtocol=https;AccountName=MyStorageAccount;AccountKey=7msknqo7qOzSxh34123Xa1gr5rglDle0KEBowa3Kz0ZapefBN45uV59YyBeFIn1v1jqe/sqeWYo12412Q==;" />
    <add name="AccountName" connectionString="Mystorageacct" />
    <add name="Key"         connectionString="7msknqo7qOzSxhdh6THUr23r23r1gr5rglDle0KEBowa3Kz0ZapefBN45uV59YyBeFIn1v1jqe/sq4234234Yoo2SfYQ==" />
  </connectionStrings>

That information can be found in your Azure Portal or Azure Storage Explorer, Here is where it appears in the portal:

AzureBlobManager.cs uses this to connect to your blob storage account:

        private static string connString = Environment.GetEnvironmentVariable("ConnString");       
         
        public AzureBlobManager()
        {
            _storageAccount = CloudStorageAccount.Parse(connString);
            _blobClient     = _storageAccount.CreateCloudBlobClient();
            _container      = _blobClient.GetContainerReference(ROOT_CONTAINER_NAME);
        }

As does the BlobStorageMultipartStreamProvider with this line:

var connectionString = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;

If hosting this in azure

Create your connection strings in the configuration tool there. Documentation.

Functionality

---

Uploading images to blob storage

This is done by making a POST request for each image you would like to upload. Navigate to nameOfWebsite/api/ImageUpload and pass in the image as a a .png or .jpg.

This function will reads the incoming multipart request, and convert it into a memory streams on the server side.

In a tool such as Postman, I would post an image like so:

And make sure that the header (in Postman at least) is empty, as Postman will fill it in automatically when it sends the data:

This takes the name of the image, pre-pends the current date, and saves the image to a container named after the current date to blob storage.

Combining images and uploading to blob storage

You can also make a Get call to nameOfWebsite/api/Images and it will combine all of the images found in a container matching today's date.

It is done with this function:

        // GET: api/Images
        /// <summary>
        /// Searches for container with current date, then combines all images into one and uploads
        /// </summary>
        public string GetCombineImagesInBlob()
        {
           var    abm = new AzureBlobManager();
           return abm.CombineImgAndUploadToBlob();
        }

Which calls:

        /// <summary>
        /// All functionality required to upload images from blob storage
        /// </summary>
        public string CombineImgAndUploadToBlob()
        {
            // Grab all images from container matching today's date
            var sContainerName = AppendDateToName(ROOT_CONTAINER_NAME              );
            GetAllBlobsInContainerAsCloudBlob(sContainerName                       );
            ConvertBlobs(sContainerName                                            );
            var combinedImg    = CombineImages(this.ImageList                      );
            var imgAsBytes     = combinedImg.ToByteArray(                          );
            var sFileName      = PrependDateToNameJpg("ImageOfDay"                 );

            // Check if container exists base on today's date
            if (DoesContainerExist(sContainerName) == true)
            {
                PutBlobAsByteArray(sContainerName, sFileName, imgAsBytes);
            }
            else
            {
                CreateContainer(sContainerName);
                PutBlobAsByteArray(sContainerName, sFileName, imgAsBytes);
            }
            ret

---

Running this on a scheduler

I have the call to api/Images being run on an Azure Scheduler every 24 hours. What this does it call that endpoint with an HTTP GET request, which fires off the CombineImgAndUploadToBlob() function.

With this, all of the images in the day's container are merged into one image, and re-uploaded so that I can analyze it later.