Read iKey from environment variable (APPINSIGHTS_INSTRUMENTATIONKEY)

CHANGELOG.md

@@ -4,6 +4,7 @@ This changelog will be used to generate documentation on [release notes page](ht
 
 ## Version 2.2.0-beta3
 
+- Read InstrumentationKey from environment variable APPINSIGHTS_INSTRUMENTATIONKEY if it is was not provided inline or through configuration (not available in PCL version of SDK).
 - Context properties `NetworkType`, `ScreenResolution` and `Language` marked as obsolete. Please use custom properties to report network type, screen resolution and language. Values stored in these properties will be send as custom properties. 
 - Dependency type was updated to reflect the latest developments in Applicaiton Insights Applicaiton Map feature. You can set a new field - `Target`. `CommandName` was renamed to `Data` for consistancy with the Application Analytics schema. `DependencyKind` will never be send any more and will not be set to "Other" by default. Also there are two more constructors for `DependencyTelemetry` item.
 - Type `SessionStateTelemetry` was marked obsolete. Use `IsFirst` flag in `SessionContext` to indicate that the session is just started.

Test/CoreSDK.Test/Shared/TelemetryClientTest.cs

@@ -445,6 +445,25 @@ public void TrackUsesInstrumentationKeyFromConfigurationWhenTheInstrumenationKey
             Assert.Equal(expectedKey, sentTelemetry.Context.InstrumentationKey);
         }
 
+        [TestMethod]
+        public void TrackUsesInstrumentationKeyFromEnvironmentVariableWhenTheInstrumenationKeyIsEmptyInConfiguration()
+        {
+            ITelemetry sentTelemetry = null;
+            var channel = new StubTelemetryChannel { OnSend = telemetry => sentTelemetry = telemetry };
+            var configuration = new TelemetryConfiguration { TelemetryChannel = channel };
+            var client = new TelemetryClient(configuration);
+            var observe = client.Context.InstrumentationKey;
+
+            string expectedKey = Guid.NewGuid().ToString();
+
+            Environment.SetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY", expectedKey);
+
+            Assert.DoesNotThrow(() => client.TrackTrace("Test Message"));
+            Assert.Equal(expectedKey, sentTelemetry.Context.InstrumentationKey);
+
+            Environment.SetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY", null);
+        }
+
         [TestMethod]
         public void TrackDoesNotInitializeInstrumentationKeyWhenItWasSetExplicitly()
         {
@@ -458,6 +477,26 @@ public void TrackDoesNotInitializeInstrumentationKeyWhenItWasSetExplicitly()
             Assert.Equal(expectedKey, client.Context.InstrumentationKey);
         }
 
+        [TestMethod]
+        public void TrackDoesNotUsesInstrumentationKeyFromEnvironmentVariableWhenTheInstrumenationKeyIsPresentInConfiguration()
+        {
+            ITelemetry sentTelemetry = null;
+            var channel = new StubTelemetryChannel { OnSend = telemetry => sentTelemetry = telemetry };
+            var configuration = new TelemetryConfiguration { TelemetryChannel = channel};
+            var client = new TelemetryClient(configuration);
+            var observe = client.Context.InstrumentationKey;
+
+            string expectedKey = Guid.NewGuid().ToString();
+            configuration.InstrumentationKey = expectedKey;
+
+            Environment.SetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY", Guid.NewGuid().ToString());
+
+            Assert.DoesNotThrow(() => client.TrackTrace("Test Message"));
+            Assert.Equal(expectedKey, sentTelemetry.Context.InstrumentationKey);
+
+            Environment.SetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY", null);
+        }
+
         [TestMethod]
         public void TrackDoesNotSendDataWhenTelemetryIsDisabled()
         {

Test/CoreSDK.Test/TestFramework/Shared/StubPlatform.cs

@@ -23,5 +23,10 @@ public IDebugOutput GetDebugOutput()
         {
             return this.OnGetDebugOutput();
         }
+
+        public string GetEnvironmentVariable(string name)
+        {
+            return Environment.GetEnvironmentVariable(name);
+        }
     }
 }

src/Core/Managed/Net40/Extensibility/Implementation/Platform/PlatformImplementation.cs

@@ -64,5 +64,10 @@ public IDebugOutput GetDebugOutput()
         {
             return this.debugOutput ?? (this.debugOutput = new TelemetryDebugWriter());
         }
+
+        public string GetEnvironmentVariable(string name)
+        {
+            return Environment.GetEnvironmentVariable(name);
+        }
     }
 }

src/Core/Managed/PCL/Extensibility/Implementation/Platform/PlatformImplementation.cs

@@ -35,5 +35,10 @@ public IDebugOutput GetDebugOutput()
 
             return this.debugOutput;
         }
+
+        public string GetEnvironmentVariable(string name)
+        {
+            return null;
+        }
     }
 }

src/Core/Managed/Shared/Extensibility/Implementation/IPlatform.cs

@@ -23,5 +23,8 @@ internal interface IPlatform
         /// Returns the platform specific Debugger writer to the VS output console.
         /// </summary>
         IDebugOutput GetDebugOutput();
+
+        // Read environment variable.
+        string GetEnvironmentVariable(string name);
     }
 }

src/Core/Managed/Shared/TelemetryClient.cs

@@ -11,6 +11,7 @@
     using Microsoft.ApplicationInsights.DataContracts;
     using Microsoft.ApplicationInsights.Extensibility;
     using Microsoft.ApplicationInsights.Extensibility.Implementation;
+    using Microsoft.ApplicationInsights.Extensibility.Implementation.Platform;
     using Microsoft.ApplicationInsights.Extensibility.Implementation.Tracing;
 
     /// <summary>
@@ -19,6 +20,7 @@
     public sealed class TelemetryClient
     {
         private const string VersionPrefix = "dotnet:";
+        private const string InstrumentationKeyWebSitesEnvironmentVariable = "APPINSIGHTS_INSTRUMENTATIONKEY";
 
         private readonly TelemetryConfiguration configuration;
         private TelemetryContext context;
@@ -371,6 +373,11 @@ public void Initialize(ITelemetry telemetry)
             if (string.IsNullOrEmpty(instrumentationKey))
             {
                 instrumentationKey = this.configuration.InstrumentationKey;
+
+                if (string.IsNullOrEmpty(instrumentationKey))
+                {
+                    instrumentationKey = PlatformSingleton.Current.GetEnvironmentVariable(InstrumentationKeyWebSitesEnvironmentVariable);
+                }
             }
 
             var telemetryWithProperties = telemetry as ISupportProperties;