feat: Powertools User-Agent for Lambda execution environment

libraries/src/AWS.Lambda.Powertools.Common/Core/Constants.cs

@@ -80,4 +80,14 @@ internal static class Constants
     ///     Constant for LAMBDA_TASK_ROOT environment variable
     /// </summary>
     internal const string LambdaTaskRoot = "LAMBDA_TASK_ROOT";
+
+    /// <summary>
+    ///     Constant for AWS_EXECUTION_ENV environment variable
+    /// </summary>
+    internal const string AwsExecutionEnvironmentVariableName = "AWS_EXECUTION_ENV";
+
+    /// <summary>
+    ///     Constant for Powertools feature identifier fo AWS_EXECUTION_ENV environment variable
+    /// </summary>
+    internal const string FeatureContextIdentifier = "PT";
 }

libraries/src/AWS.Lambda.Powertools.Common/Core/IPowertoolsConfigurations.cs

@@ -120,4 +120,10 @@ public interface IPowertoolsConfigurations
     /// <param name="defaultValue">if set to <c>true</c> [default value].</param>
     /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
     bool GetEnvironmentVariableOrDefault(string variable, bool defaultValue);
+
+    /// <summary>
+    /// Sets the execution Environment Variable (AWS_EXECUTION_ENV)
+    /// </summary>
+    /// <param name="type"></param>
+    void SetExecutionEnvironment<T>(T type);
 }

libraries/src/AWS.Lambda.Powertools.Common/Core/IPowertoolsEnvironment.cs

@@ -0,0 +1,37 @@
+namespace AWS.Lambda.Powertools.Common;
+
+/// <summary>
+/// Interface for PowertoolsEnvironment
+/// </summary>
+public interface IPowertoolsEnvironment
+{
+    /// <summary>
+    /// Get environment variable by variable name
+    /// </summary>
+    /// <param name="variableName"></param>
+    /// <returns>Environment variable</returns>
+    string GetEnvironmentVariable(string variableName);
+
+    /// <summary>
+    /// Set environment variable
+    /// </summary>
+    /// <param name="variableName"></param>
+    /// <param name="value">Setting this to null will remove environment variable with that name</param>
+    void SetEnvironmentVariable(string variableName, string value);
+
+    /// <summary>
+    /// Get the calling Type Assembly Name
+    /// </summary>
+    /// <param name="type"></param>
+    /// <typeparam name="T"></typeparam>
+    /// <returns>Assembly Name</returns>
+    string GetAssemblyName<T>(T type);
+
+    /// <summary>
+    /// Get the calling Type Assembly Version
+    /// </summary>
+    /// <param name="type"></param>
+    /// <typeparam name="T"></typeparam>
+    /// <returns>Assembly Version in the Major.Minor.Build format</returns>
+    string GetAssemblyVersion<T>(T type);
+}

libraries/src/AWS.Lambda.Powertools.Common/Core/ISystemWrapper.cs

@@ -44,4 +44,17 @@ public interface ISystemWrapper
     /// </summary>
     /// <returns>System.Double.</returns>
     double GetRandom();
+
+    /// <summary>
+    ///     Sets the environment variable.
+    /// </summary>
+    /// <param name="variable">The variable.</param>
+    /// <param name="value"></param>
+    void SetEnvironmentVariable(string variable, string value);
+
+    /// <summary>
+    /// Sets the execution Environment Variable (AWS_EXECUTION_ENV)
+    /// </summary>
+    /// <param name="type"></param>
+    void SetExecutionEnvironment<T>(T type);
 }

libraries/src/AWS.Lambda.Powertools.Common/Core/PowertoolsConfigurations.cs

@@ -184,4 +184,10 @@ public bool GetEnvironmentVariableOrDefault(string variable, bool defaultValue)
     /// <value><c>true</c> if [tracing is disabled]; otherwise, <c>false</c>.</value>
     public bool TracingDisabled =>
         GetEnvironmentVariableOrDefault(Constants.TracingDisabledEnv, false);
+
+    /// <inheritdoc />
+    public void SetExecutionEnvironment<T>(T type)
+    {
+        _systemWrapper.SetExecutionEnvironment(type);
+    }
 }

libraries/src/AWS.Lambda.Powertools.Common/Core/PowertoolsEnvironment.cs

@@ -0,0 +1,43 @@
+using System;
+
+namespace AWS.Lambda.Powertools.Common;
+
+/// <inheritdoc />
+public class PowertoolsEnvironment : IPowertoolsEnvironment
+{
+    /// <summary>
+    ///     The instance
+    /// </summary>
+    private static IPowertoolsEnvironment _instance;
+
+    /// <summary>
+    ///     Gets the instance.
+    /// </summary>
+    /// <value>The instance.</value>
+    public static IPowertoolsEnvironment Instance => _instance ??= new PowertoolsEnvironment();
+
+    /// <inheritdoc />
+    public string GetEnvironmentVariable(string variableName)
+    {
+        return Environment.GetEnvironmentVariable(variableName);
+    }
+
+    /// <inheritdoc />
+    public void SetEnvironmentVariable(string variableName, string value)
+    {
+        Environment.SetEnvironmentVariable(variableName, value);
+    }
+
+    /// <inheritdoc />
+    public string GetAssemblyName<T>(T type)
+    {
+        return type.GetType().Assembly.GetName().Name;
+    }
+
+    /// <inheritdoc />
+    public string GetAssemblyVersion<T>(T type)
+    {
+        var version = type.GetType().Assembly.GetName().Version;
+        return version != null ? $"{version.Major}.{version.Minor}.{version.Build}" : string.Empty;
+    }
+}

libraries/src/AWS.Lambda.Powertools.Common/Core/SystemWrapper.cs

@@ -14,6 +14,7 @@
  */
 
 using System;
+using System.Text;
 
 namespace AWS.Lambda.Powertools.Common;
 
@@ -24,6 +25,8 @@ namespace AWS.Lambda.Powertools.Common;
 /// <seealso cref="ISystemWrapper" />
 public class SystemWrapper : ISystemWrapper
 {
+    private static IPowertoolsEnvironment _powertoolsEnvironment;
+
     /// <summary>
     ///     The instance
     /// </summary>
@@ -32,15 +35,17 @@ public class SystemWrapper : ISystemWrapper
     /// <summary>
     ///     Prevents a default instance of the <see cref="SystemWrapper" /> class from being created.
     /// </summary>
-    private SystemWrapper()
+    public SystemWrapper(IPowertoolsEnvironment powertoolsEnvironment)
     {
+        _powertoolsEnvironment = powertoolsEnvironment;
+        _instance ??= this;
     }
 
     /// <summary>
     ///     Gets the instance.
     /// </summary>
     /// <value>The instance.</value>
-    public static ISystemWrapper Instance => _instance ??= new SystemWrapper();
+    public static ISystemWrapper Instance => _instance ??= new SystemWrapper(PowertoolsEnvironment.Instance);
 
     /// <summary>
     ///     Gets the environment variable.
@@ -49,7 +54,7 @@ private SystemWrapper()
     /// <returns>System.String.</returns>
     public string GetEnvironmentVariable(string variable)
     {
-        return Environment.GetEnvironmentVariable(variable);
+        return _powertoolsEnvironment.GetEnvironmentVariable(variable);
     }
 
     /// <summary>
@@ -78,4 +83,57 @@ public double GetRandom()
     {
         return new Random().NextDouble();
     }
+
+    /// <inheritdoc />
+    public void SetEnvironmentVariable(string variable, string value)
+    {
+        _powertoolsEnvironment.SetEnvironmentVariable(variable, value);
+    }
+
+    /// <inheritdoc />
+    public void SetExecutionEnvironment<T>(T type)
+    {
+        const string envName = Constants.AwsExecutionEnvironmentVariableName;
+        var envValue = new StringBuilder();
+        var currentEnvValue = GetEnvironmentVariable(envName);
+        var assemblyName = ParseAssemblyName(_powertoolsEnvironment.GetAssemblyName(type));
+
+        // If there is an existing execution environment variable add the annotations package as a suffix.
+        if(!string.IsNullOrEmpty(currentEnvValue))
+        {
+            // Avoid duplication - should not happen since the calling Instances are Singletons - defensive purposes
+            if (currentEnvValue.Contains(assemblyName))
+            {
+                return;
+            }
+
+            envValue.Append($"{currentEnvValue} ");
+        }
+
+        var assemblyVersion = _powertoolsEnvironment.GetAssemblyVersion(type);
+
+        envValue.Append($"{assemblyName}/{assemblyVersion}");
+
+        SetEnvironmentVariable(envName, envValue.ToString());
+    }
+
+    /// <summary>
+    /// Parsing the name to conform with the required naming convention for the UserAgent header (PTFeature/Name/Version)
+    /// Fallback to Assembly Name on exception
+    /// </summary>
+    /// <param name="assemblyName"></param>
+    /// <returns></returns>
+    private string ParseAssemblyName(string assemblyName)
+    {
+        try
+        {
+            var parsedName = assemblyName.Substring(assemblyName.LastIndexOf(".", StringComparison.Ordinal)+1);
+            return $"{Constants.FeatureContextIdentifier}/{parsedName}";
+        }
+        catch
+        {
+            //NOOP
+        }
+        return $"{Constants.FeatureContextIdentifier}/{assemblyName}";
+    }
 }

libraries/src/AWS.Lambda.Powertools.Logging/Internal/PowertoolsLogger.cs

@@ -76,6 +76,8 @@ public PowertoolsLogger(
     {
         (_name, _powertoolsConfigurations, _systemWrapper, _getCurrentConfig) = (name,
             powertoolsConfigurations, systemWrapper, getCurrentConfig);
+
+        _powertoolsConfigurations.SetExecutionEnvironment(this);
     }
 
     /// <summary>

libraries/src/AWS.Lambda.Powertools.Metrics/Metrics.cs

@@ -71,6 +71,8 @@ internal Metrics(IPowertoolsConfigurations powertoolsConfigurations, string name
         _raiseOnEmptyMetrics = raiseOnEmptyMetrics;
         _captureColdStartEnabled = captureColdStartEnabled;
         _context = InitializeContext(nameSpace, service, null);
+
+        _powertoolsConfigurations.SetExecutionEnvironment(this);
     }
 
     /// <summary>