Add AlwaysHealthy health check when provider is disabled

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AlwaysHealthyHealthCheck.cs

@@ -0,0 +1,19 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+//
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using System.Threading.Tasks;
+using System.Threading;
+
+namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
+{
+    internal sealed class AlwaysHealthyHealthCheck : IHealthCheck
+    {
+        private static readonly Task<HealthCheckResult> _healthyResult = Task.FromResult(HealthCheckResult.Healthy());
+
+        public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
+        {
+            return _healthyResult;
+        }
+    }
+}

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationExtensions.cs

@@ -7,7 +7,6 @@
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using System;
 using System.Collections.Generic;
-using System.Security;
 
 namespace Microsoft.Extensions.Configuration
 {
@@ -16,19 +15,7 @@ namespace Microsoft.Extensions.Configuration
     /// </summary>
     public static class AzureAppConfigurationExtensions
     {
-        private const string DisableProviderEnvironmentVariable = "AZURE_APP_CONFIGURATION_PROVIDER_DISABLED";
-        private static readonly bool _isProviderDisabled = IsProviderDisabled();
-
-        private static bool IsProviderDisabled()
-        {
-            try
-            {
-                return bool.TryParse(Environment.GetEnvironmentVariable(DisableProviderEnvironmentVariable), out bool disabled) ? disabled : false;
-            }
-            catch (SecurityException) { }
-
-            return false;
-        }
+        private static readonly bool _isProviderDisabled = EnvironmentVariableHelper.GetBoolOrDefault(EnvironmentVariableNames.AppConfigurationProviderDisabled);
 
         /// <summary>
         /// Adds key-value data from an Azure App Configuration store to a configuration builder using its connection string.

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationHealthCheck.cs

@@ -11,7 +11,7 @@
 
 namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
 {
-    internal class AzureAppConfigurationHealthCheck : IHealthCheck
+    internal sealed class AzureAppConfigurationHealthCheck : IHealthCheck
     {
         private static readonly PropertyInfo _propertyInfo = typeof(ChainedConfigurationProvider).GetProperty("Configuration", BindingFlags.Public | BindingFlags.Instance);
         private readonly IEnumerable<IHealthCheck> _healthChecks;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationHealthChecksBuilderExtensions.cs

@@ -14,6 +14,8 @@ namespace Microsoft.Extensions.DependencyInjection
     /// </summary>
     public static class AzureAppConfigurationHealthChecksBuilderExtensions
     {
+        private static readonly bool _isProviderDisabled = EnvironmentVariableHelper.GetBoolOrDefault(EnvironmentVariableNames.AppConfigurationProviderDisabled);
+
         /// <summary>
         /// Add a health check for Azure App Configuration to given <paramref name="builder"/>.
         /// </summary>
@@ -32,10 +34,20 @@ public static IHealthChecksBuilder AddAzureAppConfiguration(
             IEnumerable<string> tags = default,
             TimeSpan? timeout = default)
         {
+            IHealthCheck CreateHealthCheck(IServiceProvider sp)
+            {
+                if (_isProviderDisabled)
+                {
+                    return new AlwaysHealthyHealthCheck();
+                }
+
+                return new AzureAppConfigurationHealthCheck(
+                    factory?.Invoke(sp) ?? sp.GetRequiredService<IConfiguration>());
+            }
+
             return builder.Add(new HealthCheckRegistration(
                 name ?? HealthCheckConstants.HealthCheckRegistrationName,
-                sp => new AzureAppConfigurationHealthCheck(
-                    factory?.Invoke(sp) ?? sp.GetRequiredService<IConfiguration>()),
+                CreateHealthCheck,
                 failureStatus,
                 tags,
                 timeout));

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs

@@ -16,7 +16,6 @@
 using System.Net;
 using System.Net.Http;
 using System.Net.Sockets;
-using System.Security;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -143,15 +142,7 @@ public AzureAppConfigurationProvider(IConfigurationClientManager configClientMan
                 MinRefreshInterval = RefreshConstants.DefaultRefreshInterval;
             }
 
-            // Enable request tracing if not opt-out
-            string requestTracingDisabled = null;
-            try
-            {
-                requestTracingDisabled = Environment.GetEnvironmentVariable(EnvironmentVariables.DisableRequestTracing);
-            }
-            catch (SecurityException) { }
-
-            _requestTracingEnabled = bool.TryParse(requestTracingDisabled, out bool tracingDisabled) ? !tracingDisabled : true;
+            _requestTracingEnabled = !EnvironmentVariableHelper.GetBoolOrDefault(EnvironmentVariableNames.RequestTracingDisabled);
 
             if (_requestTracingEnabled)
             {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EnvironmentVariableHelper.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+//
+
+using System;
+using System.Security;
+
+namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
+{
+    internal static class EnvironmentVariableHelper
+    {
+        public static bool GetBoolOrDefault(string variableName)
+        {
+            try
+            {
+                return bool.TryParse(Environment.GetEnvironmentVariable(variableName), out bool disabled) ? disabled : false;
+            }
+            catch (SecurityException) { }
+
+            return false;
+        }
+    }
+}

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EnvironmentVariables.cs → src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EnvironmentVariableNames.cs

@@ -6,20 +6,26 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
     /// <summary>
     /// Environment variables used to configure Azure App Configuration provider behavior.
     /// </summary>
-    internal static class EnvironmentVariables
+    internal static class EnvironmentVariableNames
     {
         /// <summary>
         /// Environment variable to disable Feature Management schema compatibility.
         /// The value of this variable is a boolean string, e.g. "true" or "false".
         /// When set to "true", schema compatibility checks for feature flags are disabled,
         /// and all feature flags will be interpreted using the Microsoft Feature Flags schema.
         /// </summary>
-        public const string DisableFmSchemaCompatibility = "AZURE_APP_CONFIGURATION_FM_SCHEMA_COMPATIBILITY_DISABLED";
+        public const string FmSchemacompatibilityDisabled = "AZURE_APP_CONFIGURATION_FM_SCHEMA_COMPATIBILITY_DISABLED";
 
         /// <summary>
         /// Environment variable to disable request tracing.
         /// The value of this variable is a boolean string, e.g. "true" or "false".
         /// </summary>
-        public const string DisableRequestTracing = "AZURE_APP_CONFIGURATION_TRACING_DISABLED";
+        public const string RequestTracingDisabled = "AZURE_APP_CONFIGURATION_TRACING_DISABLED";
+
+        /// <summary>
+        /// Environment variable to disable Azure App Configuration provider.
+        /// The value of this variable is a boolean string, e.g. "true" or "false".
+        /// </summary>
+        public const string AppConfigurationProviderDisabled = "AZURE_APP_CONFIGURATION_PROVIDER_DISABLED";
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs

@@ -27,15 +27,7 @@ public FeatureManagementKeyValueAdapter(FeatureFlagTracing featureFlagTracing)
         {
             _featureFlagTracing = featureFlagTracing ?? throw new ArgumentNullException(nameof(featureFlagTracing));
 
-            string fmSchemaCompatibilityDisabled = null;
-
-            try
-            {
-                fmSchemaCompatibilityDisabled = Environment.GetEnvironmentVariable(EnvironmentVariables.DisableFmSchemaCompatibility);
-            }
-            catch (SecurityException) { }
-
-            _fmSchemaCompatibilityDisabled = bool.TryParse(fmSchemaCompatibilityDisabled, out bool disabled) ? disabled : false;
+            _fmSchemaCompatibilityDisabled = EnvironmentVariableHelper.GetBoolOrDefault(EnvironmentVariableNames.FmSchemacompatibilityDisabled);
         }
 
         public Task<IEnumerable<KeyValuePair<string, string>>> ProcessKeyValue(ConfigurationSetting setting, Uri endpoint, Logger logger, CancellationToken cancellationToken)

tests/Tests.AzureAppConfiguration/Unit/FeatureManagementTests.cs

@@ -2309,7 +2309,7 @@ public void EnvironmentVariableForcesMicrosoftSchemaForAllFlags()
             try
             {
                 // Act - Set environment variable to force Microsoft schema
-                Environment.SetEnvironmentVariable(EnvironmentVariables.DisableFmSchemaCompatibility, "true");
+                Environment.SetEnvironmentVariable(EnvironmentVariableNames.FmSchemacompatibilityDisabled, "true");
 
                 var config = new ConfigurationBuilder()
                     .AddAzureAppConfiguration(options =>

tests/Tests.AzureAppConfiguration/Unit/Tests.cs

@@ -273,7 +273,7 @@ public void TestTurnOffRequestTracing()
             var options = new AzureAppConfigurationOptions();
             options.ClientOptions.Transport = mockTransport;
 
-            Environment.SetEnvironmentVariable(EnvironmentVariables.DisableRequestTracing, "True");
+            Environment.SetEnvironmentVariable(EnvironmentVariableNames.RequestTracingDisabled, "True");
 
             var clientManager = TestHelpers.CreateMockedConfigurationClientManager(options);
             var config = new ConfigurationBuilder()
@@ -296,7 +296,7 @@ public void TestTurnOffRequestTracing()
             options.ClientOptions.Transport = mockTransport;
 
             // Delete the request tracing environment variable
-            Environment.SetEnvironmentVariable(EnvironmentVariables.DisableRequestTracing, null);
+            Environment.SetEnvironmentVariable(EnvironmentVariableNames.RequestTracingDisabled, null);
             Environment.SetEnvironmentVariable(RequestTracingConstants.AzureFunctionEnvironmentVariable, "v1.0");
 
             var clientManager1 = TestHelpers.CreateMockedConfigurationClientManager(options);