Lab 4: Access Azure Blob Storage data

Task 1: Upload a sample storage blob

On the Azure portal's navigation pane, select the Resource groups link.
On the Resource groups blade, select the ConfidentialStack resource group.
On the ConfidentialStack blade, select the securestor[yourname] storage account.
On the Storage account blade, select the Containers link in the Data storage section.
In the Containers section, select + Container.
In the New container pop-up window, perform the following actions, and then select Create:

| Setting | Action | | -- | -- | | Name text box | Enter drop | | Public access level drop-down list | Select Blob (anonymous read access for blobs only) |
Return to the Containers section, and then select the newly created drop container.
On the Container blade, select Upload.
In the Upload blob window, perform the following actions, and then select Upload:

| Setting | Action | | -- | -- | | Files section | Select the Folder icon | | File Explorer window | Browse to $HOME\training-az204\Labs\07\Starter, select the records.json file, and then select Open | | Overwrite if files already exist check box | Ensure that this check box is selected |

Note: Wait for the blob to upload before you continue with this lab.
Return to the Container blade, and then select the records.json blob in the list of blobs.
On the Blob blade, find the blob metadata, and then copy the URL for the blob.
On the taskbar, activate the shortcut menu for the Microsoft Edge icon, and then select New window.
In the new browser window, refer to the URL that you copied for the blob.
The JavaScript Object Notation (JSON) contents of the blob should now display. Close the browser window with the JSON contents.
Return to the browser window with the Azure portal, and then close the Blob blade.
Return to the Container blade, and then select Change access level.
In the Change access level pop-up window, perform the following actions:
1. In the Public access level drop-down list, select Private (no anonymous access).
2. Select OK.
On the taskbar, activate the shortcut menu for the Microsoft Edge icon, and then select New window.
In the new browser window, refer to the URL that you copied for the blob.
An error message indicating that the resource wasn't found should now display.

Note: If the error message doesn't display, your browser might have cached the file. Select Ctrl+F5 to refresh the page until the error message displays.

Task 2: Pull and configure the Azure SDK for .NET

On the taskbar, select the Windows Terminal icon.
Run the following command to change the current directory to the $HOME\training-az204\Labs\07\Starter\func empty directory:
```
 cd $HOME\training-az204\Labs\07\Starter\func
```
Run the following command to add version 12.12.0 of the Azure.Storage.Blobs package from NuGet:
```
 dotnet add package Azure.Storage.Blobs --version 12.12.0
```
Note: The Azure.Storage.Blobs NuGet package references the subset of the Azure SDK for .NET required to write code for Azure Blob Storage.
Close the currently running Windows Terminal application.
On the Start screen, select the Visual Studio Code tile.
On the File menu, select Open Folder.
In the File Explorer window that opens, browse to $HOME\training-az204\Labs\07\Starter\func, and then select Select Folder.
On the Explorer pane of the Visual Studio Code window, open the FileParser.cs file.
Add a using directive for the Azure.Storage.Blobs namespace:
```
 using Azure.Storage.Blobs;
```

Review the content of the FileParser.cs file, which should now include:

using Azure.Storage.Blobs;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.AspNetCore.Http;
using System;
using System.Threading.Tasks;   
public static class FileParser
{
    [FunctionName("FileParser")]
    public static async Task<IActionResult> Run(
        [HttpTrigger("GET")] HttpRequest request)
    {
        string connectionString = Environment.GetEnvironmentVariable("StorageConnectionString");
        return new OkObjectResult(connectionString);
    }
}

Task 3: Write Azure Blob Storage code using the Azure SDK for .NET

Within the Run method of the FileParser class, delete the following line of code:
```
 return new OkObjectResult(connectionString);
```
Still within the Run method, add the following code block to create a new instance of the BlobClient class by passing in your connectionString variable, a "drop" string value, and a "records.json" string value to the constructor:
```
 BlobClient blob = new BlobClient(connectionString, "drop", "records.json");
```
Still within the Run method, add the following code block to use the BlobClient.DownloadAsync method to download the contents of the referenced blob asynchronously, and then store the result in a variable named response:
```
 var response = await blob.DownloadAsync();
```
Still within the Run method, add the following code block to return the value of the various content stored in the content variable by using the FileStreamResult class constructor:
```
 return new FileStreamResult(response?.Value?.Content, response?.Value?.ContentType);
```

Review the content of the FileParser.cs file again, which should now include:

 using Azure.Storage.Blobs;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Azure.WebJobs;
 using Microsoft.AspNetCore.Http;
 using System;
 using System.Threading.Tasks;
 public static class FileParser
 {
     [FunctionName("FileParser")]
     public static async Task<IActionResult> Run(
         [HttpTrigger("GET")] HttpRequest request)
     {
         string connectionString = Environment.GetEnvironmentVariable("StorageConnectionString");
         BlobClient blob = new BlobClient(connectionString, "drop", "records.json");
         var response = await blob.DownloadAsync();
         return new FileStreamResult(response?.Value?.Content, response?.Value?.ContentType);
     }
 }

Select Save to save your changes to the FileParser.cs file.

Task 4: Deploy and validate the Azure Functions app

On the taskbar, select the Windows Terminal icon.
Run the following command to change the current directory to the $HOME\training-az204\Labs\07\Starter\func empty directory:
```
 cd $HOME\training-az204\Labs\07\Starter\func
```
Run the following command to sign in to the Azure CLI:
```
 az login
```
In the Microsoft Edge browser window, enter the email address and password for your Microsoft account, and then select Sign in.
Return to the currently open Windows Terminal window. Wait for the sign-in process to finish.
Run the following command to publish the function app project again (replace the <function-app-name> placeholder with the name of the function app you used earlier in this lab):
```
 func azure functionapp publish <function-app-name>
```
Note: As an example, if your Function App name is securefuncstudent, your command would be func azure functionapp publish securefuncstudent. You can review the documentation to [publish the local function app project][azure-functions-core-tools-publish-azure] using the Azure Functions Core Tools.
Wait for the deployment to finalize before you move forward with the lab.
Close the currently running Windows Terminal application.
On the taskbar, select the Microsoft Edge icon, and then refer to the Azure portal (https://portal.azure.com).
On the Azure portal's navigation pane, select the Resource groups link.
On the Resource groups blade, select the ConfidentialStack resource group.
On the ConfidentialStack blade, select the securefunc[yourname] function app.
On the App Service blade, select the Functions option in the Functions section.
On the Functions pane, select the existing FileParser function.
On the Function blade, select the Code + Test option in the Developer section.
In the function editor, select Test/Run.
In the automatically displayed pane, in the HTTP method list, select GET.
Select Run to test the function.
Review the results of the test run. The output will contain the content of the $/drop/records.json blob stored in your Azure Storage account.

Review

In this exercise, you used C# code to access a storage account, and then downloaded the contents of a blob.

LAB 4 - Access Azure Blob Storage data