Preventing unification on private host assemblies

Author: fabiocav

src/WebJobs.Script/Description/DotNet/FunctionAssemblyLoadContext.cs

@@ -22,6 +22,8 @@ namespace Microsoft.Azure.WebJobs.Script.Description
     /// </summary>
     public partial class FunctionAssemblyLoadContext : AssemblyLoadContext
     {
+        private const string PrivateDependencyResolutionPolicy = "private";
+
         private static readonly Lazy<Dictionary<string, ScriptRuntimeAssembly>> _runtimeAssemblies = new Lazy<Dictionary<string, ScriptRuntimeAssembly>>(DependencyHelper.GetRuntimeAssemblies);
         private static readonly Lazy<Dictionary<string, ResolutionPolicyEvaluator>> _resolutionPolicyEvaluators = new Lazy<Dictionary<string, ResolutionPolicyEvaluator>>(InitializeLoadPolicyEvaluators);
         private static readonly ConcurrentDictionary<string, object> _sharedContextAssembliesInFallbackLoad = new ConcurrentDictionary<string, object>();
@@ -128,7 +130,8 @@ private static Dictionary<string, ResolutionPolicyEvaluator> InitializeLoadPolic
             return new Dictionary<string, ResolutionPolicyEvaluator>
             {
                 { "minorMatchOrLower", IsMinorMatchOrLowerPolicyEvaluator },
-                { "runtimeVersion", RuntimeVersionPolicyEvaluator }
+                { "runtimeVersion", RuntimeVersionPolicyEvaluator },
+                { PrivateDependencyResolutionPolicy, (a, b) => false }
             };
         }
 
@@ -194,31 +197,42 @@ protected override Assembly Load(AssemblyName assemblyName)
                 return assembly;
             }
 
-            // If the assembly being requested matches a runtime assembly,
-            // we'll use the runtime assembly instead of loading it in this context:
-            if (TryLoadRuntimeAssembly(assemblyName, out assembly))
+            // If this is a runtime restricted assembly, load it based on unification rules
+            if (TryGetRuntimeAssembly(assemblyName, out ScriptRuntimeAssembly scriptRuntimeAssembly))
+            {
+                return LoadRuntimeAssembly(assemblyName, scriptRuntimeAssembly);
+            }
+
+            // If the assembly being requested matches a host assembly, we'll use
+            // the host assembly instead of loading it in this context:
+            if (TryLoadHostEnvironmentAssembly(assemblyName, out assembly))
             {
                 return assembly;
             }
 
-            if (TryGetRuntimeAssembly(assemblyName, out ScriptRuntimeAssembly scriptRuntimeAssembly))
+            return LoadCore(assemblyName);
+        }
+
+        private Assembly LoadRuntimeAssembly(AssemblyName assemblyName, ScriptRuntimeAssembly scriptRuntimeAssembly)
+        {
+            // If this is a private runtime assembly, return function dependency
+            if (string.Equals(scriptRuntimeAssembly.ResolutionPolicy, PrivateDependencyResolutionPolicy))
             {
-                // If there was a failure loading a runtime assembly, ensure we gracefuly unify to
-                // the runtime version of the assembly if the version falls within a safe range.
-                if (TryLoadRuntimeAssembly(new AssemblyName(assemblyName.Name), out assembly))
-                {
-                    var policyEvaluator = GetResolutionPolicyEvaluator(scriptRuntimeAssembly.ResolutionPolicy);
+                return LoadCore(assemblyName);
+            }
 
-                    if (policyEvaluator.Invoke(assemblyName, assembly))
-                    {
-                        return assembly;
-                    }
-                }
+            // Attempt to load the runtime version of the assembly based on the unification policy evaluation result.
+            if (TryLoadHostEnvironmentAssembly(assemblyName, allowPartialNameMatch: true, out Assembly assembly))
+            {
+                var policyEvaluator = GetResolutionPolicyEvaluator(scriptRuntimeAssembly.ResolutionPolicy);
 
-                return null;
+                if (policyEvaluator.Invoke(assemblyName, assembly))
+                {
+                    return assembly;
+                }
             }
 
-            return LoadCore(assemblyName);
+            return null;
         }
 
         private bool TryLoadDepsDependency(AssemblyName assemblyName, out Assembly assembly)
@@ -279,7 +293,13 @@ internal static bool TryGetDepsAsset(IDictionary<string, RuntimeAsset[]> depsAss
             return assemblyPath != null;
         }
 
-        private bool TryLoadRuntimeAssembly(AssemblyName assemblyName, out Assembly assembly)
+        private bool TryLoadHostEnvironmentAssembly(AssemblyName assemblyName, bool allowPartialNameMatch, out Assembly assembly)
+        {
+            return TryLoadHostEnvironmentAssembly(assemblyName, out assembly)
+                || (allowPartialNameMatch && TryLoadHostEnvironmentAssembly(new AssemblyName(assemblyName.Name), out assembly));
+        }
+
+        private bool TryLoadHostEnvironmentAssembly(AssemblyName assemblyName, out Assembly assembly)
         {
             assembly = null;
             try

src/WebJobs.Script/runtimeassemblies.json

@@ -2,6 +2,14 @@
 // This list originally comes from dumping TPA assemblies. 
 {
   "runtimeAssemblies": [
+    {
+      "name": "DotNetTI.BreakingChangeAnalysis",
+      "resolutionPolicy": "private"
+    },
+    {
+      "name": "Marklio.Metadata",
+      "resolutionPolicy": "private"
+    },
     {
       "name": "Microsoft.ApplicationInsights",
       "resolutionPolicy": "runtimeVersion"
@@ -738,6 +746,10 @@
       "name": "NuGet.Versioning",
       "resolutionPolicy": "minorMatchOrLower"
     },
+    {
+      "name": "protobuf-net",
+      "resolutionPolicy": "private"
+    },
     {
       "name": "SOS.NETCore",
       "resolutionPolicy": "minorMatchOrLower"

test/WebJobs.Script.Tests/Description/DotNet/FunctionAssemblyLoadContextTests.cs

@@ -20,16 +20,16 @@ namespace Microsoft.Azure.WebJobs.Script.Tests
     public class FunctionAssemblyLoadContextTests
     {
         [Theory]
-        [InlineData("Microsoft.Azure.WebJobs")]
-        [InlineData("Microsoft.Azure.WebJobs.Extensions.Http")]
-        [InlineData("Microsoft.Azure.WebJobs.Host")]
-        [InlineData("Microsoft.Azure.WebJobs.Logging")]
-        [InlineData("Microsoft.Azure.WebJobs.Logging.ApplicationInsights")]
-        [InlineData("Microsoft.Azure.WebJobs.Script")]
-        [InlineData("Microsoft.Azure.WebJobs.Script.Grpc")]
-        [InlineData("Microsoft.Azure.WebJobs.Script.WebHost")]
-        [InlineData("Microsoft.Azure.WebSites.DataProtection")]
-        [InlineData("System.IO")] // System.*
+        [InlineData("Microsoft.Azure.WebJobs, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Extensions.Http, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Host, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Logging, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Logging.ApplicationInsights, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Script, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Script.Grpc, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebJobs.Script.WebHost, Version=3.0.0.0")]
+        [InlineData("Microsoft.Azure.WebSites.DataProtection, Version=0.0.0.0")]
+        [InlineData("System.IO, Version=0.0.0.0")] // System.*
         public void RuntimeAssemblies_AreLoadedInDefaultContext(string assemblyName)
         {
             var functionContext = new FunctionAssemblyLoadContext(AppContext.BaseDirectory);