Wednesday, April 30, 2025

C# - Authenticates to Azure, retrieves a secret from Azure Key Vault, and uses it to get host details.

 using System;

using System.Threading.Tasks;

using Azure.Identity;

using Azure.Security.KeyVault.Secrets;

using Azure.Core;

using System.Diagnostics; // Required for Process.Start


public class KeyVaultExample

{

    public static async Task Main(string[] args)

    {

        // Check for required arguments.  The program expects two arguments:

        // -KeyVaultName <your_key_vault_name>

        // -SecretName <your_secret_name>

        if (args.Length != 2)

        {

            Console.WriteLine("Usage: dotnet run -- -KeyVaultName <keyVaultName> -SecretName <secretName>");

            return; // Exit the program if the arguments are not provided correctly.

        }


        string keyVaultName = "";

        string secretName = "";


        // Parse command-line arguments.  This loop iterates through the arguments

        // and extracts the values for -KeyVaultName and -SecretName.

        for (int i = 0; i < args.Length; i++)

        {

            if (args[i] == "-KeyVaultName")

            {

                if (i + 1 < args.Length)

                {

                    keyVaultName = args[i + 1];

                    i++; // Skip the next argument since it's the value of -KeyVaultName

                }

                else

                {

                    Console.WriteLine("-KeyVaultName parameter requires a value.");

                    return; // Exit if the parameter is present but the value is missing.

                }

            }

            else if (args[i] == "-SecretName")

            {

                if (i + 1 < args.Length)

                {

                    secretName = args[i + 1];

                    i++; // Skip the next argument since it's the value of -SecretName

                }

                else

                {

                    Console.WriteLine("-SecretName parameter requires a value.");

                    return; // Exit if the parameter is present but the value is missing.

                }

            }

            else

            {

                Console.WriteLine($"Unknown parameter: {args[i]}");

                return; // Exit if an unknown parameter is encountered.

            }

        }


        // Check if the required values were provided

        if (string.IsNullOrEmpty(keyVaultName))

        {

            Console.WriteLine("-KeyVaultName is required.");

            return;

        }

        if (string.IsNullOrEmpty(secretName))

        {

            Console.WriteLine("-SecretName is required.");

            return;

        }



        try

        {

            // Connect to Azure with default credentials.  DefaultAzureCredential automatically

            // tries to authenticate using various methods, such as:

            // - Environment variables

            // - Azure CLI

            // - Managed identity (if running in Azure)

            var credential = new DefaultAzureCredential();


            // Construct the Key Vault URL.  This URL is used to access your Key Vault.

            var keyVaultUrl = new Uri($"https://{keyVaultName}.vault.azure.net");


            // Create a SecretClient.  The SecretClient is used to interact with the secrets

            // in your Key Vault.  It takes the Key Vault URL and the credentials.

            var client = new SecretClient(keyVaultUrl, credential);


            Console.WriteLine($"Retrieving secret '{secretName}' from Key Vault '{keyVaultName}'...");

            // Get the secret.  This line retrieves the secret from Key Vault using the

            // SecretClient.  The GetSecretAsync method is asynchronous, so we use 'await'.

            KeyVaultSecret secret = await client.GetSecretAsync(secretName);

            string secretValue = secret.Value; // Extract the secret value.

            Console.WriteLine("Successfully retrieved secret.");


            // Use the secret to get host details (replace with your actual command).

            Console.WriteLine("Using secret to get host details (simulated)...");

            // *** IMPORTANT: Replace this with your actual command to get host details. ***

            // This is just a simulation using the secret. The actual command will depend

            // on your environment and what you are trying to achieve (e.g., connecting to

            // a remote server, calling an API, etc.).

            //

            // Example 1:  Using System.Diagnostics.Process to run a command (e.g., ssh)

            //

            //   ProcessStartInfo startInfo = new ProcessStartInfo

            //   {

            //       FileName = "ssh",  // Or "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" for PowerShell

            //       Arguments = $"-o StrictHostKeyChecking=no user@your-hostname your_command", // Add any necessary arguments

            //       RedirectStandardInput = true,

            //       RedirectStandardOutput = true,

            //       RedirectStandardError = true,

            //       UseShellExecute = false,

            //       CreateNoWindow = true, //  May want to set this to false to see output.

            //       //Password = secretValue // NEVER store the secret directly in the process start info.  Bad practice.

            //   };

            //

            //   using (Process process = new Process { StartInfo = startInfo })

            //   {

            //       process.Start();

            //

            //       //  If you need to provide a password, do it via standard input:

            //       //  if (startInfo.FileName.Contains("ssh")) // Example:  Only if it's SSH

            //       //  {

            //       //      process.StandardInput.WriteLine(secretValue);

            //       //      process.StandardInput.Close();

            //       //  }

            //

            //       string output = process.StandardOutput.ReadToEnd();

            //       string error = process.StandardError.ReadToEnd();

            //       process.WaitForExit();

            //

            //       if (process.ExitCode != 0)

            //       {

            //           Console.WriteLine($"Error: {error}");

            //           Console.WriteLine($"Command exited with code {process.ExitCode}");

            //       }

            //       else

            //       {

            //           Console.WriteLine(output);

            //       }

            //   }

            //

            // Example 2: Calling a REST API (requires a library like System.Net.Http)

            //

            //   using (var client = new HttpClient())

            //   {

            //       client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", secretValue); // Or "Basic", etc.

            //       var response = await client.GetAsync("https://your-api-endpoint");

            //       response.EnsureSuccessStatusCode();

            //       string result = await response.Content.ReadAsStringAsync();

            //       Console.WriteLine(result);

            //   }

            //

            // For this simulation, we'll just output the secret length and a message:

            //

            int secretLength = secretValue.Length;

            Console.WriteLine($"Simulated host details retrieval using secret (length: {secretLength}).");

            Console.WriteLine($"Secret Value (First 6 Characters): {secretValue.Substring(0, Math.Min(6, secretLength))}...");

            Console.WriteLine("Note: This is a simulation. You must replace this with your actual command.");

            // End of simulation. Replace this with your real code.


            Console.WriteLine("Successfully (simulated) retrieved host details.");

        }

        catch (Exception ex)

        {

            Console.WriteLine($"An error occurred: {ex.Message}");

            return; // Exit the program if an error occurs.

        }


        Console.WriteLine("Script completed."); // Indicate successful completion.

    }

}


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