[AzureMonitorDistro] Read APPLICATIONINSIGHTS_CONNECTION_STRING from …

…IConfiguration (#45292)

* Fix: Read APPLICATIONINSIGHTS_CONNECTION_STRING from IConfiguration if not set via Action<AzureMonitorOptions>

* changelog patch

sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/CHANGELOG.md

@@ -8,6 +8,13 @@
 
 ### Bugs Fixed
 
+* Fixed an issue where `APPLICATIONINSIGHTS_CONNECTION_STRING` was not read from
+  `IConfiguration` when using the `UseAzureMonitor` overload with the
+  `Action<AzureMonitorOptions>` parameter. If the connection string is not set
+  using the `Action<AzureMonitorOptions>` delegate, the distro will now check if
+  `APPLICATIONINSIGHTS_CONNECTION_STRING` is present in `IConfiguration`.
+  ([#45292](https://github.com/Azure/azure-sdk-for-net/pull/45292))
+
 ### Other Changes
 
 ## 1.3.0-beta.1 (2024-07-12)

sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/DefaultAzureMonitorOptions.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
-using System;
+using Azure.Monitor.OpenTelemetry.Exporter.Internals.Platform;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Options;
 
@@ -10,7 +10,6 @@ namespace Azure.Monitor.OpenTelemetry.AspNetCore
     internal class DefaultAzureMonitorOptions : IConfigureOptions<AzureMonitorOptions>
     {
         private const string AzureMonitorSectionFromConfig = "AzureMonitor";
-        private const string ConnectionStringEnvironmentVariable = "APPLICATIONINSIGHTS_CONNECTION_STRING";
         private readonly IConfiguration? _configuration;
 
         /// <summary>
@@ -31,15 +30,15 @@ public void Configure(AzureMonitorOptions options)
                     _configuration.GetSection(AzureMonitorSectionFromConfig).Bind(options);
 
                     // IConfiguration can read from EnvironmentVariables or InMemoryCollection if configured to do so.
-                    var connectionStringFromIConfig = _configuration[ConnectionStringEnvironmentVariable];
+                    var connectionStringFromIConfig = _configuration[EnvironmentVariableConstants.APPLICATIONINSIGHTS_CONNECTION_STRING];
                     if (!string.IsNullOrEmpty(connectionStringFromIConfig))
                     {
                         options.ConnectionString = connectionStringFromIConfig;
                     }
                 }
 
                 // Environment Variable should take precedence.
-                var connectionStringFromEnvVar = Environment.GetEnvironmentVariable(ConnectionStringEnvironmentVariable);
+                var connectionStringFromEnvVar = Environment.GetEnvironmentVariable(EnvironmentVariableConstants.APPLICATIONINSIGHTS_CONNECTION_STRING);
                 if (!string.IsNullOrEmpty(connectionStringFromEnvVar))
                 {
                     options.ConnectionString = connectionStringFromEnvVar;

sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/OpenTelemetryBuilderExtensions.cs

@@ -203,6 +203,12 @@ public static OpenTelemetryBuilder UseAzureMonitor(this OpenTelemetryBuilder bui
                     {
                         config[EnvironmentVariableConstants.HTTPCLIENT_DISABLE_URL_QUERY_REDACTION] = Boolean.TrueString;
                     }
+
+                    // If connection string is not set in the options, try to get it from configuration.
+                    if (string.IsNullOrWhiteSpace(options.ConnectionString) && config[EnvironmentVariableConstants.APPLICATIONINSIGHTS_CONNECTION_STRING] != null)
+                    {
+                        options.ConnectionString = config[EnvironmentVariableConstants.APPLICATIONINSIGHTS_CONNECTION_STRING];
+                    }
                 });
 
             return builder;

sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/tests/Azure.Monitor.OpenTelemetry.AspNetCore.Tests/OpenTelemetryBuilderExtensionsTests.cs

@@ -0,0 +1,128 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Azure.Monitor.OpenTelemetry.Exporter;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using OpenTelemetry.Trace;
+using Xunit;
+
+namespace Azure.Monitor.OpenTelemetry.AspNetCore.Tests
+{
+    public class OpenTelemetryBuilderExtensionsTests
+    {
+#if !NETFRAMEWORK
+        private const string ConnectionStringEnvironmentVariable = "APPLICATIONINSIGHTS_CONNECTION_STRING";
+
+        [Theory]
+        [InlineData(false, false, false, false, false, false, null)] // If nothing set, ConnectionString will be null.
+        [InlineData(true, false, false, false, false, false, null)] // If nothing set, ConnectionString will be null.
+        [InlineData(false, true, false, false, false, false, "testJsonValue")] // only AzureMonitor in json
+        [InlineData(true, true, false, false, false, false, null)] // only AzureMonitor in json
+        [InlineData(false, false, true, false, false, false, "testJsonEnvVarValue")] // only EnvVar in json
+        [InlineData(true, false, true, false, false, false, "testJsonEnvVarValue")] // only EnvVar in json
+        [InlineData(false, true, true, false, false, false, "testJsonEnvVarValue")] // both AzureMonitor & EnvVar in json
+        [InlineData(true, true, true, false, false, false, "testJsonEnvVarValue")] // both AzureMonitor & EnvVar in json
+        [InlineData(false, false, false, true, false, false, "testInMemoryCollectionValue")] // only IConfig InMemoryCollection
+        [InlineData(true, false, false, true, false, false, "testInMemoryCollectionValue")] // only IConfig InMemoryCollection
+        [InlineData(false, false, false, false, true, false, null)] // only IConfig EnvVars, without EnvVar set.
+        [InlineData(true, false, false, false, true, false, null)] // only IConfig EnvVars, without EnvVar set.
+        [InlineData(false, false, false, false, true, true, "testEnvVarValue")] // only IConfig EnvVars, with EnvVar set.
+        [InlineData(true, false, false, false, true, true, "testEnvVarValue")] // only IConfig EnvVars, with EnvVar set.
+        [InlineData(false, false, false, true, true, true, "testEnvVarValue")] // both IConfig InMemoryCollection & IConfig EnvVars with EnvVar set
+        [InlineData(true, false, false, true, true, true, "testEnvVarValue")] // both IConfig InMemoryCollection & IConfig EnvVars with EnvVar set
+        [InlineData(false, false, false, true, true, false, "testInMemoryCollectionValue")] // both IConfig InMemoryCollection & IConfig EnvVars without EnvVar set
+        [InlineData(true, false, false, true, true, false, "testInMemoryCollectionValue")] // both IConfig InMemoryCollection & IConfig EnvVars without EnvVar set
+        [InlineData(false, false, false, false, false, true, "testEnvVarValue")] // only EnvironmentVariable
+        [InlineData(true, false, false, false, false, true, "testEnvVarValue")] // only EnvironmentVariable
+        [InlineData(false, true, true, true, true, true, "testEnvVarValue")]
+        [InlineData(true, true, true, true, true, true, "testEnvVarValue")]
+        public void Verify_UseAzureMonitor_SetsConnectionString(bool useConfigure, bool jsonAzureMonitor, bool jsonEnvVar, bool iconfigCollection, bool iconfigEnvVar, bool setEnvVar, string expectedConnectionStringValue)
+        {
+            try
+            {
+                Environment.SetEnvironmentVariable(ConnectionStringEnvironmentVariable, setEnvVar ? "testEnvVarValue" : null);
+
+                // BUILD JSON STRING
+                var jsonString = "{";
+
+                if (jsonAzureMonitor)
+                {
+                    jsonString += @"""AzureMonitor"":{ ""ConnectionString"" : ""testJsonValue"" }";
+                }
+
+                if (jsonAzureMonitor && jsonEnvVar)
+                {
+                    jsonString += ",";
+                }
+
+                if (jsonEnvVar)
+                {
+                    jsonString += @"""APPLICATIONINSIGHTS_CONNECTION_STRING"" :  ""testJsonEnvVarValue""";
+                }
+
+                jsonString += "}";
+
+                // BUILD CONFIGURATION OBJECT
+                var configBulider = new ConfigurationBuilder();
+                bool usesConfigBuilder = false;
+
+                if (jsonAzureMonitor || jsonEnvVar)
+                {
+                    configBulider.AddJsonStream(new MemoryStream(Encoding.UTF8.GetBytes(jsonString)));
+                    usesConfigBuilder = true;
+                }
+
+                if (iconfigCollection)
+                {
+                    configBulider.AddInMemoryCollection(new Dictionary<string, string?> { [ConnectionStringEnvironmentVariable] = "testInMemoryCollectionValue" });
+                    usesConfigBuilder = true;
+                }
+
+                if (iconfigEnvVar)
+                {
+                    configBulider.AddEnvironmentVariables();
+                }
+
+                // ACT
+                var serviceCollection = new ServiceCollection();
+
+                if (usesConfigBuilder)
+                {
+                    var configuration = configBulider.Build();
+                    serviceCollection.AddSingleton<IConfiguration>(configuration);
+                }
+
+                if (useConfigure)
+                {
+                    serviceCollection.AddOpenTelemetry().UseAzureMonitor(x => { });
+                }
+                else
+                {
+                    serviceCollection.AddOpenTelemetry().UseAzureMonitor();
+                }
+
+                using var serviceProvider = serviceCollection.BuildServiceProvider();
+
+                // ASSERT
+                var azureMonitorOptions = serviceProvider.GetServices<IOptions<AzureMonitorOptions>>().Single().Value;
+                Assert.Equal(expectedConnectionStringValue, azureMonitorOptions.ConnectionString);
+
+                var azureMonitorExporterOptions = serviceProvider.GetServices<IOptions<AzureMonitorExporterOptions>>().Single().Value;
+                Assert.Equal(expectedConnectionStringValue, azureMonitorExporterOptions.ConnectionString);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(ConnectionStringEnvironmentVariable, null);
+            }
+        }
+#endif
+    }
+}