Ensure HealthCheck respects configured proxy settings

Fixes OctopusDeploy/Issues#7544

Updates the HealthCheck to use the new version of
the Azure SDKs. It's in beta, so not touching the
actual deployment code at this stage.

Author: mjhilton

source/Calamari/Azure/AzureClient.cs

@@ -1,5 +1,8 @@
 using System.Net;
 using System.Net.Http;
+using Azure.Core.Pipeline;
+using Azure.Identity;
+using Azure.ResourceManager;
 using Microsoft.Azure.Management.Fluent;
 using Microsoft.Azure.Management.ResourceManager.Fluent;
 
@@ -23,5 +26,24 @@ public static IAzure CreateAzureClient(this ServicePrincipalAccount servicePrinc
                 .Authenticate(credentials)
                 .WithSubscription(servicePrincipal.SubscriptionNumber);
         }
+
+        /// <summary>
+        /// Creates an ArmClient for the new Azure SDK, which replaces the older fluent libraries.
+        /// We should migrate to this SDK once it stabilises.
+        /// </summary>
+        /// <param name="servicePrincipal">Service Principal Account to use when connecting to Azure</param>
+        /// <returns></returns>
+        public static ArmClient CreateArmClient(this ServicePrincipalAccount servicePrincipal)
+        {
+            var environment = new AzureKnownEnvironment(servicePrincipal.AzureEnvironment).AsAzureArmEnvironment();
+
+            var httpClientTransport = new HttpClientTransport(new HttpClientHandler { Proxy = WebRequest.DefaultWebProxy });
+
+            var tokenCredentialOptions = new TokenCredentialOptions { Transport = httpClientTransport };
+            var credential = new ClientSecretCredential(servicePrincipal.TenantId, servicePrincipal.ClientId, servicePrincipal.Password, tokenCredentialOptions);
+
+            var armClientOptions = new ArmClientOptions() { Transport = httpClientTransport, Environment = environment };
+            return new ArmClient(credential, defaultSubscriptionId: servicePrincipal.SubscriptionNumber, armClientOptions);
+        }
     }
 }

source/Calamari/Azure/AzureKnownEnvironment.cs

@@ -1,4 +1,5 @@
 using System;
+using Azure.ResourceManager;
 using Microsoft.Azure.Management.ResourceManager.Fluent;
 
 namespace Calamari.Azure
@@ -15,11 +16,11 @@ public AzureKnownEnvironment(string environment)
             if (string.IsNullOrEmpty(environment) || environment == "AzureCloud") // This environment name is defined in Sashimi.Azure.Accounts.AzureEnvironmentsListAction
                 Value = Global.Value;                                             // We interpret it as the normal Azure environment for historical reasons)
 
-            azureEnvironment = AzureEnvironment.FromName(Value) ??
+            azureSdkEnvironment = AzureEnvironment.FromName(Value) ??
                                throw new InvalidOperationException($"Unknown environment name {Value}");
         }
 
-        private readonly AzureEnvironment azureEnvironment;
+        private readonly AzureEnvironment azureSdkEnvironment;
         public string Value { get; }
 
         public static readonly AzureKnownEnvironment Global = new AzureKnownEnvironment("AzureGlobalCloud");
@@ -29,7 +30,18 @@ public AzureKnownEnvironment(string environment)
 
         public AzureEnvironment AsAzureSDKEnvironment()
         {
-            return azureEnvironment;
+            return azureSdkEnvironment;
         }
+
+        public ArmEnvironment AsAzureArmEnvironment() => ToArmEnvironment(Value);
+
+        private static ArmEnvironment ToArmEnvironment(string name) => name switch
+        {
+            "AzureGlobalCloud" => ArmEnvironment.AzurePublicCloud,
+            "AzureChinaCloud" => ArmEnvironment.AzureChina,
+            "AzureGermanCloud" => ArmEnvironment.AzureGermany,
+            "AzureUSGovernment" => ArmEnvironment.AzureGovernment,
+            _ => throw  new InvalidOperationException($"ARM Environment {name} is not a known Azure Environment name.")
+        };
     }
 }

source/Calamari/Calamari.csproj

@@ -16,6 +16,8 @@
     <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
+    <PackageReference Include="Azure.Identity" Version="1.2.3" />
+    <PackageReference Include="Azure.ResourceManager.AppService" Version="1.0.0-beta.2" />
     <PackageReference Include="Calamari.Common" Version="21.1.0" />
     <PackageReference Include="Microsoft.Azure.Management.AppService.Fluent" Version="1.37.1" />
     <PackageReference Include="Microsoft.Azure.Management.Fluent" Version="1.37.1" />

source/Calamari/HealthCheckCommand.cs

@@ -1,10 +1,12 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using Azure;
+using Azure.ResourceManager.AppService;
+using Azure.ResourceManager.Resources;
 using Calamari.Azure;
 using Calamari.Common.Commands;
 using Calamari.Common.Plumbing.Pipeline;
-using Microsoft.Azure.Management.ResourceManager.Fluent;
 
 namespace Calamari.AzureAppService
 {
@@ -34,14 +36,21 @@ public Task Execute(RunningDeployment context)
             return ConfirmWebAppExists(account, resourceGroupName, webAppName);
         }
 
-        async Task ConfirmWebAppExists(ServicePrincipalAccount servicePrincipal, string resourceGroupName, string siteAndSlotName)
+        private async Task ConfirmWebAppExists(ServicePrincipalAccount servicePrincipal, string resourceGroupName, string siteAndSlotName)
         {
-            var azureClient = servicePrincipal.CreateAzureClient(); 
-            var webApp = await azureClient.WebApps.GetByResourceGroupAsync(resourceGroupName, siteAndSlotName);
-            if (webApp == null)
+            var client = servicePrincipal.CreateArmClient();
+            var subscription = await client.GetDefaultSubscriptionAsync();
+            var resourceGroups = subscription.GetResourceGroups();
+
+            try
+            {
+                ResourceGroupResource resourceGroup = await resourceGroups.GetAsync(resourceGroupName);
+                _ = await resourceGroup.GetWebSiteAsync(siteAndSlotName);
+            }
+            catch (RequestFailedException rfe) when (rfe.Status == 404)
             {
-                throw new Exception($"Could not find site {siteAndSlotName} in resource group {resourceGroupName}, using Service Principal with subscription {servicePrincipal.SubscriptionNumber}");
+                throw new Exception($"Could not find site {siteAndSlotName} in resource group {resourceGroupName}, using Service Principal with subscription {servicePrincipal.SubscriptionNumber}", rfe);
             }
         }
     }
-}
+}