Azure App Service Tags (DataDog#646)

* collect resource id for azure app services

src/Datadog.Trace/Agent/Api.cs

@@ -2,9 +2,9 @@
 using System.Collections.Generic;
 using System.Net.Http;
 using System.Threading.Tasks;
-using Datadog.Trace.Containers;
 using Datadog.Trace.DogStatsd;
 using Datadog.Trace.Logging;
+using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.Vendors.StatsdClient;
 using MsgPack.Serialization;
 using Newtonsoft.Json;
@@ -65,7 +65,7 @@ public Api(Uri baseEndpoint, DelegatingHandler delegatingHandler, IStatsd statsd
             _client.DefaultRequestHeaders.Add(AgentHttpHeaderNames.TracerVersion, TracerConstants.AssemblyVersion);
 
             // report container id (only Linux containers supported for now)
-            var containerId = ContainerInfo.GetContainerId();
+            var containerId = ContainerMetadata.GetContainerId();
 
             if (containerId != null)
             {

src/Datadog.Trace/PlatformHelpers/AzureAppservices.cs

@@ -0,0 +1,130 @@
+using System;
+using System.Collections;
+using Datadog.Trace.ExtensionMethods;
+using Datadog.Trace.Logging;
+
+namespace Datadog.Trace.PlatformHelpers
+{
+    internal class AzureAppServices
+    {
+        /// <summary>
+        /// Configuration key which is used as a flag to tell us whether we are running in the context of Azure App Services.
+        /// </summary>
+        internal static readonly string AzureAppServicesContextKey = "DD_AZURE_APP_SERVICES";
+
+        /// <summary>
+        /// Example: 8c56d827-5f07-45ce-8f2b-6c5001db5c6f+apm-dotnet-EastUSwebspace
+        /// Format: {subscriptionId}+{planResourceGroup}-{hostedInRegion}
+        /// </summary>
+        internal static readonly string WebsiteOwnerNameKey = "WEBSITE_OWNER_NAME";
+
+        /// <summary>
+        /// This is the name of the resource group the site instance is assigned to.
+        /// </summary>
+        internal static readonly string ResourceGroupKey = "WEBSITE_RESOURCE_GROUP";
+
+        /// <summary>
+        /// This is the unique name of the website instance within azure app services.
+        /// </summary>
+        internal static readonly string SiteNameKey = "WEBSITE_DEPLOYMENT_ID";
+
+        static AzureAppServices()
+        {
+            Metadata = new AzureAppServices(Environment.GetEnvironmentVariables());
+        }
+
+        public AzureAppServices(IDictionary environmentVariables)
+        {
+            IsRelevant = GetVariableIfExists(AzureAppServicesContextKey, environmentVariables)?.ToBoolean() ?? false;
+            if (IsRelevant)
+            {
+                SubscriptionId = GetSubscriptionId(environmentVariables);
+                ResourceGroup = GetVariableIfExists(ResourceGroupKey, environmentVariables);
+                SiteName = GetVariableIfExists(SiteNameKey, environmentVariables);
+                ResourceId = CompileResourceId();
+            }
+        }
+
+        public static AzureAppServices Metadata { get; set; }
+
+        public bool IsRelevant { get; }
+
+        public string SubscriptionId { get; }
+
+        public string ResourceGroup { get; }
+
+        public string SiteName { get; }
+
+        public string ResourceId { get; }
+
+        private string CompileResourceId()
+        {
+            string resourceId = null;
+
+            try
+            {
+                var success = true;
+                if (SubscriptionId == null)
+                {
+                    success = false;
+                    DatadogLogging.RegisterStartupLog(log => log.Warning("Could not successfully retrieve the subscription ID from variable: {0}", WebsiteOwnerNameKey));
+                }
+
+                if (SiteName == null)
+                {
+                    success = false;
+                    DatadogLogging.RegisterStartupLog(log => log.Warning("Could not successfully retrieve the deployment ID from variable: {0}", SiteNameKey));
+                }
+
+                if (ResourceGroup == null)
+                {
+                    success = false;
+                    DatadogLogging.RegisterStartupLog(log => log.Warning("Could not successfully retrieve the resource group name from variable: {0}", ResourceGroupKey));
+                }
+
+                if (success)
+                {
+                    resourceId = $"/subscriptions/{SubscriptionId}/resourcegroups/{ResourceGroup}/providers/microsoft.web/sites/{SiteName}".ToLowerInvariant();
+                }
+            }
+            catch (Exception ex)
+            {
+                DatadogLogging.RegisterStartupLog(log => log.Error(ex, "Could not successfully setup the resource id for azure app services."));
+            }
+
+            return resourceId;
+        }
+
+        private string GetSubscriptionId(IDictionary environmentVariables)
+        {
+            try
+            {
+                var websiteOwner = GetVariableIfExists(WebsiteOwnerNameKey, environmentVariables);
+                if (!string.IsNullOrWhiteSpace(websiteOwner))
+                {
+                    var plusSplit = websiteOwner.Split('+');
+                    if (plusSplit.Length > 0 && !string.IsNullOrWhiteSpace(plusSplit[0]))
+                    {
+                        return plusSplit[0];
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                DatadogLogging.RegisterStartupLog(log => log.Error(ex, "Could not successfully retrieve the subscription id for azure app services."));
+            }
+
+            return null;
+        }
+
+        private string GetVariableIfExists(string key, IDictionary environmentVariables)
+        {
+            if (environmentVariables.Contains(key))
+            {
+                return environmentVariables[key]?.ToString();
+            }
+
+            return null;
+        }
+    }
+}

src/Datadog.Trace/Containers/ContainerInfo.cs → src/Datadog.Trace/PlatformHelpers/ContainerMetadata.cs

@@ -2,25 +2,24 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Runtime.InteropServices;
 using System.Text.RegularExpressions;
 using System.Threading;
 using Datadog.Trace.Logging;
 
-namespace Datadog.Trace.Containers
+namespace Datadog.Trace.PlatformHelpers
 {
     /// <summary>
     /// Utility class with methods to interact with container hosts.
     /// </summary>
-    internal static class ContainerInfo
+    internal static class ContainerMetadata
     {
         private const string ControlGroupsFilePath = "/proc/self/cgroup";
 
         private const string ContainerIdRegex = @"^(?:\d+):(?:[^:]*):/?(?:.+/)([0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}|[0-9a-f]{64}(?:\.scope)?)$";
 
         private static readonly Lazy<string> ContainerId = new Lazy<string>(GetContainerIdInternal, LazyThreadSafetyMode.ExecutionAndPublication);
 
-        private static readonly Vendors.Serilog.ILogger Log = DatadogLogging.GetLogger(typeof(ContainerInfo));
+        private static readonly Vendors.Serilog.ILogger Log = DatadogLogging.GetLogger(typeof(ContainerMetadata));
 
         /// <summary>
         /// Gets the id of the container executing the code.

src/Datadog.Trace/Tags.cs

@@ -180,5 +180,25 @@ public static class Tags
         /// Language tag, applied to root spans that are .NET runtime (e.g., ASP.NET)
         /// </summary>
         public const string Language = "language";
+
+        /// <summary>
+        /// The resource id of the site instance in azure app services where the traced application is running.
+        /// </summary>
+        public const string AzureAppServicesResourceId = "aas.resource.id";
+
+        /// <summary>
+        /// The resource group of the site instance in azure app services where the traced application is running.
+        /// </summary>
+        public const string AzureAppServicesResourceGroup = "aas.resource.group";
+
+        /// <summary>
+        /// The site name of the site instance in azure app services where the traced application is running.
+        /// </summary>
+        public const string AzureAppServicesSiteName = "aas.site.name";
+
+        /// <summary>
+        /// The subscription id of the site instance in azure app services where the traced application is running.
+        /// </summary>
+        public const string AzureAppServicesSubscriptionId = "aas.subscription.id";
     }
 }

src/Datadog.Trace/TraceContext.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using Datadog.Trace.Logging;
+using Datadog.Trace.PlatformHelpers;
 
 namespace Datadog.Trace
 {
@@ -54,6 +55,7 @@ public void AddSpan(Span span)
                 {
                     // first span added is the root span
                     RootSpan = span;
+                    DecorateRootSpan(span);
 
                     if (_samplingPriority == null)
                     {
@@ -126,5 +128,16 @@ public void LockSamplingPriority()
                 _samplingPriorityLocked = true;
             }
         }
+
+        private void DecorateRootSpan(Span span)
+        {
+            if (AzureAppServices.Metadata?.IsRelevant ?? false)
+            {
+                span.SetTag(Tags.AzureAppServicesSiteName, AzureAppServices.Metadata.SiteName);
+                span.SetTag(Tags.AzureAppServicesResourceGroup, AzureAppServices.Metadata.ResourceGroup);
+                span.SetTag(Tags.AzureAppServicesSubscriptionId, AzureAppServices.Metadata.SubscriptionId);
+                span.SetTag(Tags.AzureAppServicesResourceId, AzureAppServices.Metadata.ResourceId);
+            }
+        }
     }
 }

src/Datadog.Trace/Tracer.cs

@@ -9,6 +9,7 @@
 using Datadog.Trace.DiagnosticListeners;
 using Datadog.Trace.DogStatsd;
 using Datadog.Trace.Logging;
+using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.Sampling;
 using Datadog.Trace.Vendors.StatsdClient;
 
@@ -356,17 +357,6 @@ void IDatadogTracer.Write(List<Span> trace)
             _agentWriter.WriteTrace(trace);
         }
 
-        /// <summary>
-        /// Create an Uri to the Agent using host and port from
-        /// the specified <paramref name="settings"/>.
-        /// </summary>
-        /// <param name="settings">A <see cref="TracerSettings"/> object </param>
-        /// <returns>An Uri that can be used to send traces to the Agent.</returns>
-        internal static Uri GetAgentUri(TracerSettings settings)
-        {
-            return settings.AgentUri;
-        }
-
         internal async Task FlushAsync()
         {
             await _agentWriter.FlushAndCloseAsync();

test/Datadog.Trace.ClrProfiler.IntegrationTests/AzureAppServices/FakeAzureAppServicesTests.cs

@@ -1,4 +1,5 @@
 using System.IO;
+using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.TestHelpers;
 using Xunit;
 using Xunit.Abstractions;
@@ -12,7 +13,7 @@ public class FakeAzureAppServicesTests : TestHelper
         public FakeAzureAppServicesTests(ITestOutputHelper output)
             : base(SampleName, output)
         {
-            SetEnvironmentVariable("DD_AZURE_APP_SERVICES", "1");
+            SetEnvironmentVariable(PlatformHelpers.AzureAppServices.AzureAppServicesContextKey, "1");
         }
 
         [Fact(Skip = "TODO: Traces from the sub process are not coming through")]

test/Datadog.Trace.ClrProfiler.IntegrationTests/AzureAppServices/FakeKuduTests.cs

@@ -1,4 +1,5 @@
 using System.Threading;
+using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.TestHelpers;
 using Xunit;
 using Xunit.Abstractions;
@@ -10,7 +11,7 @@ public class FakeKuduTests : TestHelper
         public FakeKuduTests(ITestOutputHelper output)
             : base("FakeKudu", output)
         {
-            SetEnvironmentVariable("DD_AZURE_APP_SERVICES", "1");
+            SetEnvironmentVariable(PlatformHelpers.AzureAppServices.AzureAppServicesContextKey, "1");
             SetEnvironmentVariable("APP_POOL_ID", "~1KuduScmProcessIsFilteredByTilde");
         }
 

test/Datadog.Trace.IntegrationTests/ContainerTaggingTests.cs

@@ -2,7 +2,7 @@
 using System.Threading.Tasks;
 using Datadog.Core.Tools;
 using Datadog.Trace.Configuration;
-using Datadog.Trace.Containers;
+using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.TestHelpers;
 using Xunit;
 using Xunit.Abstractions;
@@ -21,7 +21,7 @@ public ContainerTaggingTests(ITestOutputHelper output)
         [Fact]
         public async Task Http_Headers_Contain_ContainerId()
         {
-            string expectedContainedId = ContainerInfo.GetContainerId();
+            string expectedContainedId = ContainerMetadata.GetContainerId();
             string actualContainerId = null;
             var agentPort = TcpPortProvider.GetOpenPort();