fix: Generate consistent reuse hashes by sorting dictionary keys (#1554)

Author: 0xced

src/Testcontainers/Configurations/Commons/JsonIgnoreRuntimeResourceLabels.cs

@@ -1,39 +1,20 @@
 namespace DotNet.Testcontainers.Configurations
 {
-  using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text.Json;
-  using System.Text.Json.Serialization;
   using DotNet.Testcontainers.Clients;
   using DotNet.Testcontainers.Containers;
 
-  internal sealed class JsonIgnoreRuntimeResourceLabels : JsonConverter<IReadOnlyDictionary<string, string>>
+  internal sealed class JsonIgnoreRuntimeResourceLabels : JsonOrderedKeysConverter
   {
     private static readonly ISet<string> IgnoreLabels = new HashSet<string> { ResourceReaper.ResourceReaperSessionLabel, TestcontainersClient.TestcontainersVersionLabel, TestcontainersClient.TestcontainersSessionIdLabel };
 
-    public override bool CanConvert(Type typeToConvert)
-    {
-      return typeof(IEnumerable<KeyValuePair<string, string>>).IsAssignableFrom(typeToConvert);
-    }
-
-    public override IReadOnlyDictionary<string, string> Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-    {
-      return JsonSerializer.Deserialize<IReadOnlyDictionary<string, string>>(ref reader);
-    }
-
     public override void Write(Utf8JsonWriter writer, IReadOnlyDictionary<string, string> value, JsonSerializerOptions options)
     {
       var labels = value.Where(label => !IgnoreLabels.Contains(label.Key)).ToDictionary(label => label.Key, label => label.Value);
 
-      writer.WriteStartObject();
-
-      foreach (var label in labels)
-      {
-        writer.WriteString(label.Key, label.Value);
-      }
-
-      writer.WriteEndObject();
+      base.Write(writer, labels, options);
     }
   }
 }

src/Testcontainers/Configurations/Commons/JsonOrderedKeysConverter.cs

@@ -0,0 +1,33 @@
+namespace DotNet.Testcontainers.Configurations
+{
+  using System;
+  using System.Collections.Generic;
+  using System.Linq;
+  using System.Text.Json;
+  using System.Text.Json.Serialization;
+
+  internal class JsonOrderedKeysConverter : JsonConverter<IReadOnlyDictionary<string, string>>
+  {
+    public override bool CanConvert(Type typeToConvert)
+    {
+      return typeof(IEnumerable<KeyValuePair<string, string>>).IsAssignableFrom(typeToConvert);
+    }
+
+    public override IReadOnlyDictionary<string, string> Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+      return JsonSerializer.Deserialize<IReadOnlyDictionary<string, string>>(ref reader);
+    }
+
+    public override void Write(Utf8JsonWriter writer, IReadOnlyDictionary<string, string> value, JsonSerializerOptions options)
+    {
+      writer.WriteStartObject();
+
+      foreach (var item in value.OrderBy(item => item.Key))
+      {
+        writer.WriteString(item.Key, item.Value);
+      }
+
+      writer.WriteEndObject();
+    }
+  }
+}

src/Testcontainers/Configurations/Commons/ResourceConfiguration.cs

@@ -14,6 +14,13 @@ namespace DotNet.Testcontainers.Configurations
   [PublicAPI]
   public class ResourceConfiguration<TCreateResourceEntity> : IResourceConfiguration<TCreateResourceEntity>
   {
+    private static readonly JsonSerializerOptions JsonSerializerOptions;
+
+    static ResourceConfiguration()
+    {
+      JsonSerializerOptions = new JsonSerializerOptions { Converters = { new JsonOrderedKeysConverter() } };
+    }
+
     /// <summary>
     /// Initializes a new instance of the <see cref="ResourceConfiguration{TCreateResourceEntity}" /> class.
     /// </summary>
@@ -88,7 +95,7 @@ protected ResourceConfiguration(IResourceConfiguration<TCreateResourceEntity> ol
     /// <inheritdoc />
     public virtual string GetReuseHash()
     {
-      var jsonUtf8Bytes = JsonSerializer.SerializeToUtf8Bytes(this, GetType());
+      var jsonUtf8Bytes = JsonSerializer.SerializeToUtf8Bytes(this, GetType(), JsonSerializerOptions);
 
 #if NET6_0_OR_GREATER
       return Convert.ToBase64String(SHA1.HashData(jsonUtf8Bytes));

tests/Testcontainers.Platform.Linux.Tests/ReusableResourceTest.cs

@@ -100,6 +100,44 @@ public async Task ShouldReuseExistingResource()
 
     public static class ReuseHashTest
     {
+        public sealed class EqualTest
+        {
+            [Fact]
+            [Trait(nameof(DockerCli.DockerPlatform), nameof(DockerCli.DockerPlatform.Linux))]
+            public void ForSameConfigurationCreatedInDifferentOrder()
+            {
+                var env1 = new Dictionary<string, string>
+                {
+                    ["keyA"] = "valueA",
+                    ["keyB"] = "valueB",
+                };
+                var env2 = new Dictionary<string, string>
+                {
+                    ["keyB"] = "valueB",
+                    ["keyA"] = "valueA",
+                };
+                var hash1 = new ReuseHashContainerBuilder().WithEnvironment(env1).WithLabel("labelA", "A").WithLabel("labelB", "B").GetReuseHash();
+                var hash2 = new ReuseHashContainerBuilder().WithEnvironment(env2).WithLabel("labelB", "B").WithLabel("labelA", "A").GetReuseHash();
+                Assert.Equal(hash1, hash2);
+            }
+
+            [Fact]
+            [Trait(nameof(DockerCli.DockerPlatform), nameof(DockerCli.DockerPlatform.Linux))]
+            public void ForGivenConfiguration()
+            {
+                var env = new Dictionary<string, string>
+                {
+                    ["keyB"] = "valueB",
+                    ["keyA"] = "valueA",
+                };
+                var hash = new ReuseHashContainerBuilder().WithEnvironment(env).WithLabel("labelB", "B").WithLabel("labelA", "A").GetReuseHash();
+
+                // 50MEP+vnxEkQFo5PrndJ7oKOfh8= is the base64 encoded SHA1 of this JSON:
+                // {"Image":null,"Name":null,"Entrypoint":null,"Command":[],"Environments":{"keyA":"valueA","keyB":"valueB"},"ExposedPorts":{},"PortBindings":{},"NetworkAliases":[],"ExtraHosts":[],"Labels":{"labelA":"A","labelB":"B","org.testcontainers":"true","org.testcontainers.lang":"dotnet"}}
+                Assert.Equal("50MEP+vnxEkQFo5PrndJ7oKOfh8=", hash);
+            }
+        }
+
         public sealed class NotEqualTest
         {
             [Fact]