private static Assembly AssemblyResolve_ManagedProfilerDependencies(object sender, ResolveEventArgs args)
{
var assemblyName = new AssemblyName(args.Name);
// On .NET Framework, having a non-US locale can cause mscorlib
// to enter the AssemblyResolve event when searching for resources
// in its satellite assemblies. This seems to have been fixed in
// .NET Core in the 2.0 servicing branch, so we should not see this
// occur, but guard against it anyways. If we do see it, exit early
// so we don't cause infinite recursion.
if (string.Equals(assemblyName.Name, "System.Private.CoreLib.resources", StringComparison.OrdinalIgnoreCase) ||
string.Equals(assemblyName.Name, "System.Net.Http", StringComparison.OrdinalIgnoreCase))
{
return(null);
}
var path = Path.Combine(ManagedProfilerDirectory, $"{assemblyName.Name}.dll");
// Only load the main profiler into the default Assembly Load Context.
// If Datadog.Trace or other libraries are provided by the NuGet package their loads are handled in the following two ways.
// 1) The AssemblyVersion is greater than or equal to the version used by Datadog.Trace, the assembly
// will load successfully and will not invoke this resolve event.
// 2) The AssemblyVersion is lower than the version used by Datadog.Trace, the assembly will fail to load
// and invoke this resolve event. It must be loaded in a separate AssemblyLoadContext since the application will only
// load the originally referenced version
if (File.Exists(path))
{
StartupLogger.Debug("Loading {0} with DependencyLoadContext.LoadFromAssemblyPath", path);
return(DependencyLoadContext.LoadFromAssemblyPath(path)); // Load unresolved framework and third-party dependencies into a custom Assembly Load Context
}
return(null);
}
private static string ResolveManagedProfilerDirectory()
{
string tracerFrameworkDirectory = "netstandard2.0";
var version = Environment.Version;
// Old versions of .net core have a major version of 4
if ((version.Major == 3 && version.Minor >= 1) || version.Major >= 5)
{
tracerFrameworkDirectory = "netcoreapp3.1";
}
var tracerHomeDirectory = ReadEnvironmentVariable("DD_DOTNET_TRACER_HOME") ?? string.Empty;
var fullPath = Path.Combine(tracerHomeDirectory, tracerFrameworkDirectory);
// We use the List/Array approach due the number of files in the tracer home folder (7 in netstandard, 2 netcoreapp3.1)
var assemblies = new List <CachedAssembly>();
foreach (var file in Directory.EnumerateFiles(fullPath, "*.dll", SearchOption.TopDirectoryOnly))
{
assemblies.Add(new CachedAssembly(file, null));
}
_assemblies = assemblies.ToArray();
StartupLogger.Debug("Total number of assemblies: {0}", _assemblies.Length);
return(fullPath);
}
private static Assembly ResolveAssembly(string name)
{
var assemblyName = new AssemblyName(name);
StartupLogger.Debug("Assembly Resolve event received for: {0}", name);
// On .NET Framework, having a non-US locale can cause mscorlib
// to enter the AssemblyResolve event when searching for resources
// in its satellite assemblies. Exit early so we don't cause
// infinite recursion.
if (string.Equals(assemblyName.Name, "mscorlib.resources", StringComparison.OrdinalIgnoreCase) ||
string.Equals(assemblyName.Name, "System.Net.Http", StringComparison.OrdinalIgnoreCase))
{
return(null);
}
var path = Path.Combine(ManagedProfilerDirectory, $"{assemblyName.Name}.dll");
StartupLogger.Debug("Looking for: {0}", path);
if (File.Exists(path))
{
if (name.StartsWith("SignalFx.Tracing, Version=") && name != AssemblyName)
{
StartupLogger.Debug("Trying to load {0} which does not match the expected version ({1}). [Path={2}]", name, AssemblyName, path);
return(null);
}
StartupLogger.Debug("Resolving {0}, loading {1}", name, path);
return(Assembly.LoadFrom(path));
}
StartupLogger.Debug("Assembly not found in path: {0}", path);
return(null);
}
private static Assembly AssemblyResolve_ManagedProfilerDependencies(object sender, ResolveEventArgs args)
{
var assemblyName = new AssemblyName(args.Name);
// On .NET Framework, having a non-US locale can cause mscorlib
// to enter the AssemblyResolve event when searching for resources
// in its satellite assemblies. This seems to have been fixed in
// .NET Core in the 2.0 servicing branch, so we should not see this
// occur, but guard against it anyways. If we do see it, exit early
// so we don't cause infinite recursion.
if (string.Equals(assemblyName.Name, "System.Private.CoreLib.resources", StringComparison.OrdinalIgnoreCase) ||
string.Equals(assemblyName.Name, "System.Net.Http", StringComparison.OrdinalIgnoreCase))
{
return(null);
}
var path = Path.Combine(ManagedProfilerDirectory, $"{assemblyName.Name}.dll");
if (assemblyName.Name.StartsWith("Datadog.Trace", StringComparison.OrdinalIgnoreCase) &&
assemblyName.FullName.IndexOf("PublicKeyToken=def86d061d0d2eeb", StringComparison.OrdinalIgnoreCase) >= 0 &&
File.Exists(path))
{
StartupLogger.Debug("Loading {0} with Assembly.LoadFrom", path);
return(Assembly.LoadFrom(path)); // Load the main profiler and tracer into the default Assembly Load Context
}
else if (File.Exists(path))
{
StartupLogger.Debug("Loading {0} with DependencyLoadContext.LoadFromAssemblyPath", path);
return(DependencyLoadContext.LoadFromAssemblyPath(path)); // Load unresolved framework and third-party dependencies into a custom Assembly Load Context
}
return(null);
}
private static Assembly AssemblyResolve_ManagedProfilerDependencies(object sender, ResolveEventArgs args)
{
var assemblyName = new AssemblyName(args.Name).Name;
// On .NET Framework, having a non-US locale can cause mscorlib
// to enter the AssemblyResolve event when searching for resources
// in its satellite assemblies. Exit early so we don't cause
// infinite recursion.
if (string.Equals(assemblyName, "mscorlib.resources", StringComparison.OrdinalIgnoreCase) ||
string.Equals(assemblyName, "System.Net.Http", StringComparison.OrdinalIgnoreCase))
{
return(null);
}
var path = Path.Combine(ManagedProfilerDirectory, $"{assemblyName}.dll");
if (File.Exists(path))
{
if (args.Name.StartsWith("Datadog.Trace, Version=") && args.Name != AssemblyName)
{
StartupLogger.Debug("Trying to load {0} which does not match the expected version ({1})", args.Name, AssemblyName);
return(null);
}
StartupLogger.Debug("Resolving {0}, loading {1}", args.Name, path);
return(Assembly.LoadFrom(path));
}
return(null);
}
private static string ReadEnvironmentVariable(string key)
{
try
{
return(Environment.GetEnvironmentVariable(key));
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Error while loading environment variable " + key);
}
return(null);
}
/// <summary>
/// Initializes static members of the <see cref="Startup"/> class.
/// This method also attempts to load the Datadog.Trace.ClrProfiler.Managed .NET assembly.
/// </summary>
static Startup()
{
ManagedProfilerDirectory = ResolveManagedProfilerDirectory();
try
{
AppDomain.CurrentDomain.AssemblyResolve += AssemblyResolve_ManagedProfilerDependencies;
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Unable to register a callback to the CurrentDomain.AssemblyResolve event.");
}
TryLoadManagedAssembly();
}
private static void TryInvokeManagedMethod(string typeName, string methodName)
{
try
{
var assembly = Assembly.Load(AssemblyName);
if (assembly != null)
{
var type = assembly.GetType(typeName, throwOnError: false);
var method = type?.GetRuntimeMethod(methodName, parameters: Type.EmptyTypes);
method?.Invoke(obj: null, parameters: null);
}
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Error when invoking managed method: {0}.{1}", typeName, methodName);
}
}
private static void TryLoadManagedAssembly()
{
try
{
var assembly = Assembly.Load("Datadog.Trace.ClrProfiler.Managed, Version=1.26.3.0, Culture=neutral, PublicKeyToken=def86d061d0d2eeb");
if (assembly != null)
{
// call method Datadog.Trace.ClrProfiler.Instrumentation.Initialize()
var type = assembly.GetType("Datadog.Trace.ClrProfiler.Instrumentation", throwOnError: false);
var method = type?.GetRuntimeMethod("Initialize", parameters: new Type[0]);
method?.Invoke(obj: null, parameters: null);
}
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Error when loading managed assemblies.");
}
}
private static Assembly LoadAssembly(string assemblyString)
{
try
{
return(Assembly.Load(assemblyString));
}
catch (FileNotFoundException ex)
{
// In some IIS scenarios the `AssemblyResolve` event doesn't get triggered and we received this exception.
// We will try to resolve it manually as a last chance.
StartupLogger.Log(ex, "Error on assembly load: {0}, Trying to solve it manually...", assemblyString);
var assembly = ResolveAssembly(assemblyString);
if (assembly is not null)
{
StartupLogger.Log("Assembly resolved manually.");
}
return(assembly);
}
}
private static void TryInvokeManagedMethod(string typeName, string methodName)
{
try
{
var assembly = LoadAssembly(AssemblyName);
if (assembly == null)
{
StartupLogger.Log("Assembly '{0}' cannot be loaded. The managed method ({1}.{2}) cannot be invoked", AssemblyName, typeName, methodName);
return;
}
var type = assembly.GetType(typeName, throwOnError: false);
var method = type?.GetRuntimeMethod(methodName, parameters: Type.EmptyTypes);
method?.Invoke(obj: null, parameters: null);
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Error when invoking managed method: {0}.{1}", typeName, methodName);
}
}
/// <summary>
/// Initializes static members of the <see cref="Startup"/> class.
/// This method also attempts to load the SignalFx.TracingTrace .NET assembly.
/// </summary>
static Startup()
{
ManagedProfilerDirectory = ResolveManagedProfilerDirectory();
StartupLogger.Debug("Resolving managed profiler directory to: {0}", ManagedProfilerDirectory);
try
{
AppDomain.CurrentDomain.AssemblyResolve += AssemblyResolve_ManagedProfilerDependencies;
}
catch (Exception ex)
{
StartupLogger.Log(ex, "Unable to register a callback to the CurrentDomain.AssemblyResolve event.");
}
var runInAas = ReadBooleanEnvironmentVariable(AzureAppServicesKey, false);
if (!runInAas)
{
TryInvokeManagedMethod("Datadog.Trace.ClrProfiler.Instrumentation", "Initialize");
return;
}
// In AAS, the loader can be used to load the tracer, the traceagent only (if only custom tracing is enabled),
// dogstatsd or all of them.
var customTracingEnabled = ReadBooleanEnvironmentVariable(AasCustomTracingKey, false);
var needsDogStatsD = ReadBooleanEnvironmentVariable(AasCustomMetricsKey, false);
var automaticTraceEnabled = ReadBooleanEnvironmentVariable(TraceEnabledKey, true);
if (automaticTraceEnabled || customTracingEnabled || needsDogStatsD)
{
StartupLogger.Log("Invoking managed method to start external processes.");
TryInvokeManagedMethod("Datadog.Trace.AgentProcessManager", "Initialize");
}
if (automaticTraceEnabled)
{
StartupLogger.Log("Invoking managed tracer.");
TryInvokeManagedMethod("Datadog.Trace.ClrProfiler.Instrumentation", "Initialize");
}
}