Add support for Labels to the Image config

Microsoft.NET.Build.Containers/CreateNewImage.cs

@@ -66,6 +66,11 @@ public class CreateNewImage : Microsoft.Build.Utilities.Task
     /// </summary>
     public ITaskItem[] EntrypointArgs { get; set; }
 
+    /// <summary>
+    /// Labels that the image configuration will include in metadata
+    /// </summary>
+    public ITaskItem[] Labels { get; set; }
+
     public CreateNewImage()
     {
         BaseRegistry = "";
@@ -78,6 +83,7 @@ public CreateNewImage()
         WorkingDirectory = "";
         Entrypoint = Array.Empty<ITaskItem>();
         EntrypointArgs = Array.Empty<ITaskItem>();
+        Labels = Array.Empty<ITaskItem>();
     }
 
 
@@ -112,6 +118,11 @@ public override bool Execute()
         image.WorkingDirectory = WorkingDirectory;
         image.SetEntrypoint(Entrypoint.Select(i => i.ItemSpec).ToArray(), EntrypointArgs.Select(i => i.ItemSpec).ToArray());
 
+        foreach (var label in Labels)
+        {
+            image.Label(label.ItemSpec, label.GetMetadata("Value"));
+        }
+
         if (OutputRegistry.StartsWith("docker://"))
         {
             try

Microsoft.NET.Build.Containers/Image.cs

@@ -5,6 +5,8 @@
 
 namespace Microsoft.NET.Build.Containers;
 
+record Label(string name, string value);
+
 public class Image
 {
     public JsonNode manifest;
@@ -15,12 +17,16 @@ public class Image
 
     internal List<Layer> newLayers = new();
 
+    private HashSet<Label> labels;
+
     public Image(JsonNode manifest, JsonNode config, string name, Registry? registry)
     {
         this.manifest = manifest;
         this.config = config;
         this.OriginatingName = name;
         this.originatingRegistry = registry;
+        // labels are inherited from the parent image, so we need to seed our new image with them.
+        this.labels = ReadLabelsFromConfig(config);
     }
 
     public IEnumerable<Descriptor> LayerDescriptors
@@ -61,7 +67,39 @@ private void RecalculateDigest()
         manifest["config"]!["digest"] = GetDigest(config);
     }
 
-    static JsonArray ToJsonArray(string[] items) => new JsonArray(items.Where(s => !string.IsNullOrEmpty(s)).Select(s =>(JsonValue) s).ToArray());
+    private static HashSet<Label> ReadLabelsFromConfig(JsonNode inputConfig)
+    {
+        if (inputConfig is JsonObject config && config["Labels"] is JsonObject labelsJson)
+        {
+            // read label mappings from object
+            var labels = new HashSet<Label>();
+            foreach (var property in labelsJson)
+            {
+                if (property.Key is { } propertyName && property.Value is JsonValue propertyValue)
+                {
+                    labels.Add(new(propertyName, propertyValue.ToString()));
+                }
+            }
+            return labels;
+        }
+        else
+        {
+            // initialize and empty labels map
+            return new HashSet<Label>();
+        }
+    }
+
+    private JsonObject CreateLabelMap()
+    {
+        var container = new JsonObject();
+        foreach (var label in labels)
+        {
+            container.Add(label.name, label.value);
+        }
+        return container;
+    }
+
+    static JsonArray ToJsonArray(string[] items) => new JsonArray(items.Where(s => !string.IsNullOrEmpty(s)).Select(s => (JsonValue)s).ToArray());
 
     public void SetEntrypoint(string[] executableArgs, string[]? args = null)
     {
@@ -86,14 +124,23 @@ public void SetEntrypoint(string[] executableArgs, string[]? args = null)
         RecalculateDigest();
     }
 
-    public string WorkingDirectory {
-        get => (string?)manifest["config"]!["WorkingDir"] ?? "";
-        set {
+    public string WorkingDirectory
+    {
+        get => (string?)config["config"]!["WorkingDir"] ?? "";
+        set
+        {
             config["config"]!["WorkingDir"] = value;
             RecalculateDigest();
         }
     }
 
+    public void Label(string name, string value)
+    {
+        labels.Add(new(name, value));
+        config["config"]!["Labels"] = CreateLabelMap();
+        RecalculateDigest();
+    }
+
     public string GetDigest(JsonNode json)
     {
         string hashString;

Microsoft.NET.Build.Containers/build/Microsoft.NET.Build.Containers.targets

@@ -25,17 +25,20 @@
             <ContainerWorkingDirectory Condition="'$(ContainerWorkingDirectory)' == ''">/app</ContainerWorkingDirectory>
             <!-- Could be semicolon-delimited -->
         </PropertyGroup>
-
-        <ItemGroup>
-            <ContainerLabel Condition="@(ContainerLabel) == ''"></ContainerLabel>
+
+        <ItemGroup Label="Entrypoint Assignment">
             <!-- For non-apphosts, we need to invoke `dotnet` `workingdir/app` as separate args -->
             <ContainerEntrypoint Condition="'$(ContainerEntrypoint)' == '' and '$(UseAppHost)' != 'true'" Include="dotnet;$(ContainerWorkingDirectory)/$(TargetFileName)" />
             <!-- For apphosts, we need to invoke `workingdir/app` as a single arg -->
             <ContainerEntrypoint Condition="'$(ContainerEntrypoint)' == '' and '$(UseAppHost)' == 'true'" Include="$(ContainerWorkingDirectory)/$(AssemblyName)$(_NativeExecutableExtension)" />
         </ItemGroup>
 
+        <ItemGroup Label="Conventional Label assignment">
+            <ContainerLabel Include="org.opencontainers.image.created" Value="$([System.DateTime]::UtcNow.ToString('o'))" />
+        </ItemGroup>
+
         <!-- Asp.NET defaults -->
-        <ItemGroup Condition="'$(_IsAspNet)' == 'true'">
+        <ItemGroup Label="ASP.NET port forwarding" Condition="'$(_IsAspNet)' == 'true'">
             <ContainerPort Include="80" Type="tcp" Condition="@(ContainerPort->WithMetadataValue('Identity', '80')->AnyHaveMetadataValue('Type', 'tcp')) == ''" />
 
             <ContainerEnvironmentVariable Include="ASPNETCORE_URLS" Value="http://localhost:5000;https://localhost:5001"
@@ -72,6 +75,7 @@
                         PublishDirectory="$(PublishDir)"
                         WorkingDirectory="$(ContainerWorkingDirectory)"
                         Entrypoint="@(ContainerEntrypoint)"
-                        EntrypointArgs="@(ContainerEntrypointArgs)"/>
+                        EntrypointArgs="@(ContainerEntrypointArgs)"
+						Labels="@(ContainerLabel)"/>
     </Target>
 </Project>