chore: Metrics disabled environment variable

docs/core/metrics-v2.md

@@ -58,12 +58,16 @@ Visit the AWS documentation for a complete explanation for [Amazon CloudWatch co
 
 **`Metrics`** is implemented as a Singleton to keep track of your aggregate metrics in memory and make them accessible anywhere in your code. To guarantee that metrics are flushed properly the **`MetricsAttribute`** must be added on the lambda handler.
 
-Metrics has two global settings that will be used across all metrics emitted. Use your application or main service as the metric namespace to easily group all metrics:
+Metrics has three global settings that will be used across all metrics emitted. Use your application or main service as the metric namespace to easily group all metrics:
 
-Setting | Description | Environment variable | Constructor parameter
-------------------------------------------------- | ------------------------------------------------- | ------------------------------------------------- | -------------------------------------------------
-**Service** | Optionally, sets **service** metric dimension across all metrics e.g. `payment` | `POWERTOOLS_SERVICE_NAME` | `Service`
-**Metric namespace** | Logical container where all metrics will be placed e.g. `MyCompanyEcommerce` |  `POWERTOOLS_METRICS_NAMESPACE` | `Namespace`
+ Setting                       | Description                                                                     | Environment variable | Decorator parameter 
+-------------------------------|---------------------------------------------------------------------------------| ------------------------------------------------- |-----------------------
+ **Metric namespace**          | Logical container where all metrics will be placed e.g. `MyCompanyEcommerce`    |  `POWERTOOLS_METRICS_NAMESPACE` | `Namespace`           
+ **Service**                   | Optionally, sets **Service** metric dimension across all metrics e.g. `payment` | `POWERTOOLS_SERVICE_NAME` | `Service`             
+**Disable Powertools Metrics** | Optionally, disables all Powertools metrics                                     |`POWERTOOLS_METRICS_DISABLED`                           | N/A                   |
+
+???+ info
+    `POWERTOOLS_METRICS_DISABLED` will not disable default metrics created by AWS services.
 
 !!! info "Autocomplete Metric Units"
     All parameters in **`Metrics Attribute`** are optional. Following rules apply:
@@ -73,13 +77,6 @@ Setting | Description | Environment variable | Constructor parameter
       - **CaptureColdStart:** **`false`** by default. 
       - **RaiseOnEmptyMetrics:** **`false`** by default.
 
-### Full list of environment variables
-
-| Environment variable | Description | Default |
-| ------------------------------------------------- | --------------------------------------------------------------------------------- |  ------------------------------------------------- |
-| **POWERTOOLS_SERVICE_NAME** | Sets service name used for tracing namespace, metrics dimension and structured logging | `"service_undefined"` |
-| **POWERTOOLS_METRICS_NAMESPACE** | Sets namespace used for metrics | `None` |
-
 ### Metrics object
 
 #### Attribute

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

@@ -130,4 +130,9 @@ internal static class Constants
     /// Constant for POWERTOOLS_BATCH_THROW_ON_FULL_BATCH_FAILURE environment variable
     /// </summary>
     internal const string BatchThrowOnFullBatchFailureEnv = "POWERTOOLS_BATCH_THROW_ON_FULL_BATCH_FAILURE";
+
+    /// <summary>
+    /// Constant for POWERTOOLS_METRICS_DISABLED environment variable
+    /// </summary>
+    internal const string PowertoolsMetricsDisabledEnv = "POWERTOOLS_METRICS_DISABLED";
 }

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

@@ -155,11 +155,16 @@ public interface IPowertoolsConfigurations
     /// Gets the maximum degree of parallelism to apply during batch processing.
     /// </summary>
     /// <value>Defaults to 1 (no parallelism). Specify -1 to automatically use the value of <see cref="System.Environment.ProcessorCount">ProcessorCount</see>.</value>
-    int BatchProcessingMaxDegreeOfParallelism { get; }
-
+    int BatchProcessingMaxDegreeOfParallelism { get; }
+
     /// <summary>
     /// Gets a value indicating whether Batch processing will throw an exception on full batch failure.
     /// </summary>
     /// <value>Defaults to true</value>
     bool BatchThrowOnFullBatchFailureEnabled { get; }
+
+    /// <summary>
+    /// Gets a value indicating whether Metrics are disabled.
+    /// </summary>
+    bool MetricsDisabled { get; }
 }

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

@@ -219,4 +219,7 @@ public void SetExecutionEnvironment<T>(T type)
 
     /// <inheritdoc />
     public bool BatchThrowOnFullBatchFailureEnabled => GetEnvironmentVariableOrDefault(Constants.BatchThrowOnFullBatchFailureEnv, true);
+
+    /// <inheritdoc />
+    public bool MetricsDisabled => GetEnvironmentVariableOrDefault(Constants.PowertoolsMetricsDisabledEnv, false);
 }

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

@@ -109,6 +109,11 @@ public static IMetrics Instance
     /// </summary>
     private readonly IConsoleWrapper _consoleWrapper;
 
+    /// <summary>
+    ///   Gets a value indicating whether metrics are disabled.
+    /// </summary>
+    private bool _disabled;
+
     /// <summary>
     ///    Initializes a new instance of the <see cref="Metrics" /> class.
     /// </summary>
@@ -170,6 +175,8 @@ internal Metrics(IPowertoolsConfigurations powertoolsConfigurations, string name
         _captureColdStartEnabled = captureColdStartEnabled;
         _options = options;
 
+        _disabled = _powertoolsConfigurations.MetricsDisabled;
+
         Instance = this;
         _powertoolsConfigurations.SetExecutionEnvironment(this);
 
@@ -180,6 +187,9 @@ internal Metrics(IPowertoolsConfigurations powertoolsConfigurations, string name
     /// <inheritdoc />
     void IMetrics.AddMetric(string key, double value, MetricUnit unit, MetricResolution resolution)
     {
+        if(_disabled)
+            return;
+
         if (Instance != null)
         {
             if (string.IsNullOrWhiteSpace(key))
@@ -274,6 +284,9 @@ void IMetrics.SetDefaultDimensions(Dictionary<string, string> defaultDimensions)
     /// <inheritdoc />
     void IMetrics.Flush(bool metricsOverflow)
     {
+        if(_disabled)
+            return;
+
         if (_context.GetMetrics().Count == 0
             && _raiseOnEmptyMetrics)
             throw new SchemaValidationException(true);
@@ -342,6 +355,9 @@ private Dictionary<string, string> GetDefaultDimensions()
     void IMetrics.PushSingleMetric(string name, double value, MetricUnit unit, string nameSpace,
         string service, Dictionary<string, string> dimensions, MetricResolution resolution)
     {
+        if(_disabled)
+            return;
+
         if (string.IsNullOrWhiteSpace(name))
             throw new ArgumentNullException(nameof(name),
                 "'PushSingleMetric' method requires a valid metrics key. 'Null' or empty values are not allowed.");

libraries/tests/AWS.Lambda.Powertools.Common.Tests/ConsoleWrapperTests.cs

@@ -31,6 +31,7 @@ public void Error_Should_Write_To_Error_Console()
 
         // Act
         consoleWrapper.Error("error message");
+        writer.Flush();
 
         // Assert
         Assert.Equal($"error message{Environment.NewLine}", writer.ToString());

libraries/tests/AWS.Lambda.Powertools.Metrics.Tests/MetricsTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using Amazon.Lambda.Core;
 using Amazon.Lambda.TestUtilities;
 using AWS.Lambda.Powertools.Common;
@@ -62,6 +63,51 @@ public void Before_When_RaiseOnEmptyMetricsNotSet_Should_Configure_Null()
         Assert.False(metrics.Options.RaiseOnEmptyMetrics);
     }
 
+    [Fact]
+    public void When_MetricsDisabled_Should_Not_AddMetric()
+    {
+        // Arrange
+        var conf = Substitute.For<IPowertoolsConfigurations>();
+        conf.MetricsDisabled.Returns(true);
+
+        IMetrics metrics = new Metrics(conf);
+        var stringWriter = new StringWriter();
+        Console.SetOut(stringWriter);
+
+        // Act
+        metrics.AddMetric("test", 1.0);
+        metrics.Flush();
+
+        // Assert
+        Assert.Empty(stringWriter.ToString());
+
+        // Cleanup
+        stringWriter.Dispose();
+        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()));
+    }
+
+    [Fact]
+    public void When_MetricsDisabled_Should_Not_PushSingleMetric()
+    {
+        // Arrange
+        var conf = Substitute.For<IPowertoolsConfigurations>();
+        conf.MetricsDisabled.Returns(true);
+
+        IMetrics metrics = new Metrics(conf);
+        var stringWriter = new StringWriter();
+        Console.SetOut(stringWriter);
+
+        // Act
+        metrics.PushSingleMetric("test", 1.0, MetricUnit.Count);
+
+        // Assert
+        Assert.Empty(stringWriter.ToString());
+
+        // Cleanup
+        stringWriter.Dispose();
+        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()));
+    }
+
     // Helper method for the tests
     internal void TestMethod(ILambdaContext context)
     {