implement AWS Lambda detector

Signed-off-by: AzharH <[email protected]>

Author: AzharH

src/OpenTelemetry.Instrumentation.AWSLambda/AWSLambdaResourceBuilderExtensions.cs

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using OpenTelemetry.AWS;
+using OpenTelemetry.Instrumentation.AWSLambda.Implementation;
+using OpenTelemetry.Internal;
+using OpenTelemetry.Resources;
+
+namespace OpenTelemetry.Instrumentation.AWSLambda;
+
+/// <summary>
+/// Extension methods to simplify registering of AWS Lambda resource detectors.
+/// </summary>
+public static class AWSLambdaResourceBuilderExtensions
+{
+    /// <summary>
+    /// Enables AWS Lambda resource detector.
+    /// </summary>
+    /// <param name="builder">The <see cref="ResourceBuilder"/> being configured.</param>
+    /// <param name="configure">Optional callback action for configuring <see cref="AWSLambdaInstrumentationOptions"/>.</param>
+    /// <returns>The instance of <see cref="ResourceBuilder"/> being configured.</returns>
+    public static ResourceBuilder AddAWSLambdaDetector(this ResourceBuilder builder, Action<AWSLambdaInstrumentationOptions>? configure = null)
+    {
+        Guard.ThrowIfNull(builder);
+
+        var options = new AWSLambdaInstrumentationOptions();
+        configure?.Invoke(options);
+
+        var semanticConventionBuilder = new AWSSemanticConventions(options.SemanticConventionVersion);
+
+        return builder.AddDetector(new AWSLambdaResourceDetector(semanticConventionBuilder));
+    }
+}

test/OpenTelemetry.Instrumentation.AWSLambda.Tests/AWSLambdaResourceBuilderExtensionsTests.cs

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using OpenTelemetry.Resources;
+using Xunit;
+
+namespace OpenTelemetry.Instrumentation.AWSLambda.Tests;
+
+public class AWSLambdaResourceBuilderExtensionsTests
+{
+    // Expected Semantic Conventions
+    private const string AttributeCloudProvider = "cloud.provider";
+    private const string AttributeCloudRegion = "cloud.region";
+    private const string AttributeFaasName = "faas.name";
+    private const string AttributeFaasVersion = "faas.version";
+    private const string AttributeFaasInstance = "faas.instance";
+    private const string AttributeFaasMaxMemory = "faas.max_memory";
+
+    public AWSLambdaResourceBuilderExtensionsTests()
+    {
+        Environment.SetEnvironmentVariable("AWS_REGION", "us-east-1");
+        Environment.SetEnvironmentVariable("AWS_LAMBDA_FUNCTION_NAME", "testfunction");
+        Environment.SetEnvironmentVariable("AWS_LAMBDA_FUNCTION_VERSION", "latest");
+        Environment.SetEnvironmentVariable("AWS_LAMBDA_FUNCTION_MEMORY_SIZE", "128");
+        Environment.SetEnvironmentVariable("AWS_LAMBDA_LOG_STREAM_NAME",
+            "2025/07/21/[$LATEST]7b176c212e954e62adfb9b5451cb5374");
+    }
+
+    [Fact]
+    public void AssertAttributes()
+    {
+        var resourceBuilder = ResourceBuilder.CreateDefault();
+        resourceBuilder.AddAWSLambdaDetector();
+
+        var resource = resourceBuilder.Build();
+
+        var resourceAttributes = resource.Attributes
+            .ToDictionary(x => x.Key, x => x.Value);
+
+        Assert.Equal("aws", resourceAttributes[AttributeCloudProvider]);
+        Assert.Equal("us-east-1", resourceAttributes[AttributeCloudRegion]);
+        Assert.Equal("testfunction", resourceAttributes[AttributeFaasName]);
+        Assert.Equal("latest", resourceAttributes[AttributeFaasVersion]);
+        Assert.Equal("2025/07/21/[$LATEST]7b176c212e954e62adfb9b5451cb5374",
+            resourceAttributes[AttributeFaasInstance]);
+        Assert.Equal(134217728L, resourceAttributes[AttributeFaasMaxMemory]);
+    }
+
+    [Fact]
+    public void AssertArgumentNullException() =>
+        Assert.Throws<ArgumentNullException>(() => AWSLambdaResourceBuilderExtensions.AddAWSLambdaDetector(null!));
+}