Re-apply dry-run fix for CopyImageService publish config lookup (#1972)

PR #1966 fixed `CopyImageService.ImportImageAsync` to skip the
`PublishConfiguration` lookup in dry-run mode. This fix was
inadvertently reverted by the logging migration in #1968 due to a bad
merge.

1. **Test** — Added `CopyImageServiceTests` with a test that exercises
`ImportImageAsync` in dry-run mode with an empty `PublishConfiguration`,
verifying it does not throw.
2. **Fix** — Moved `GetRegistryResource` calls and all Azure import
logic after an early return for `isDryRun`, so dry-run mode only logs
what would happen without requiring registry authentication details.

Fixes pipeline failures in #1963.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: lbussell

src/ImageBuilder.Tests/CopyImageServiceTests.cs

@@ -0,0 +1,38 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Threading.Tasks;
+using Microsoft.DotNet.ImageBuilder.Configuration;
+using Microsoft.DotNet.ImageBuilder.Tests.Helpers;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Shouldly;
+using Xunit;
+
+namespace Microsoft.DotNet.ImageBuilder.Tests;
+
+public class CopyImageServiceTests
+{
+    /// <summary>
+    /// When isDryRun is true and the publish configuration has no registry authentication,
+    /// ImportImageAsync should succeed without throwing. This scenario occurs in PR validation
+    /// pipelines where appsettings.json is not generated.
+    /// </summary>
+    [Fact]
+    public async Task ImportImageAsync_DryRun_DoesNotRequirePublishConfiguration()
+    {
+        var emptyConfig = new PublishConfiguration();
+        var service = new CopyImageService(
+            Mock.Of<ILogger<CopyImageService>>(),
+            Mock.Of<IAzureTokenCredentialProvider>(),
+            ConfigurationHelper.CreateOptionsMock(emptyConfig));
+
+        await Should.NotThrowAsync(() =>
+            service.ImportImageAsync(
+                destTagNames: ["myacr.azurecr.io/repo:tag"],
+                destAcrName: "myacr.azurecr.io",
+                srcTagName: "repo:tag",
+                srcRegistryName: "docker.io",
+                isDryRun: true));
+    }
+}

src/ImageBuilder/CopyImageService.cs

@@ -53,13 +53,28 @@ public async Task ImportImageAsync(
         ContainerRegistryImportSourceCredentials? sourceCredentials = null,
         bool isDryRun = false)
     {
+        Acr destAcr = Acr.Parse(destAcrName);
+
+        string action = isDryRun ? "(Dry run) Would have imported" : "Importing";
+        string sourceImageName = DockerHelper.GetImageName(srcRegistryName, srcTagName);
+        var destinationImageNames = destTagNames
+            .Select(tag => $"'{DockerHelper.GetImageName(destAcr.Name, tag)}'")
+            .ToList();
+        string formattedDestinationImages = string.Join(", ", destinationImageNames);
+        _logger.LogInformation("{Action} {DestinationImages} from '{SourceImage}'",
+            action, formattedDestinationImages, sourceImageName);
+
+        if (isDryRun)
+        {
+            _logger.LogInformation("Importing skipped due to dry run.");
+            return;
+        }
+
         var destResourceId = _publishConfig.GetRegistryResource(destAcrName);
         var srcResourceId = srcRegistryName is not null
             ? _publishConfig.GetRegistryResource(srcRegistryName)
             : null;
 
-        Acr destAcr = Acr.Parse(destAcrName);
-
         // Azure ACR import only supports one source identifier. Use ResourceId for ACR-to-ACR
         // imports (same tenant), or RegistryAddress for external registries.
         ContainerRegistryImportSource importSrc = new(srcTagName)
@@ -76,34 +91,19 @@ public async Task ImportImageAsync(
 
         importImageContent.TargetTags.AddRange(destTagNames);
 
-        string action = isDryRun ? "(Dry run) Would have imported" : "Importing";
-        string sourceImageName = DockerHelper.GetImageName(srcRegistryName, srcTagName);
-        var destinationImageNames = destTagNames
-            .Select(tag => $"'{DockerHelper.GetImageName(destAcr.Name, tag)}'")
-            .ToList();
-        string formattedDestinationImages = string.Join(", ", destinationImageNames);
-        _logger.LogInformation($"{action} {formattedDestinationImages} from '{sourceImageName}'");
+        ArmClient armClient = GetArmClientForAcr(destAcrName);
+        ContainerRegistryResource registryResource = armClient.GetContainerRegistryResource(destResourceId);
 
-        if (!isDryRun)
+        try
         {
-            ArmClient armClient = GetArmClientForAcr(destAcrName);
-            ContainerRegistryResource registryResource = armClient.GetContainerRegistryResource(destResourceId);
-
-            try
-            {
-                await RetryHelper.GetWaitAndRetryPolicy<Exception>(_logger)
-                    .ExecuteAsync(() => registryResource.ImportImageAsync(WaitUntil.Completed, importImageContent));
-            }
-            catch (Exception e)
-            {
-                _logger.LogError(e, "Importing Failure: {DestinationImages}", formattedDestinationImages);
-
-                throw;
-            }
+            await RetryHelper.GetWaitAndRetryPolicy<Exception>(_logger)
+                .ExecuteAsync(() => registryResource.ImportImageAsync(WaitUntil.Completed, importImageContent));
         }
-        else
+        catch (Exception e)
         {
-            _logger.LogInformation("Importing skipped due to dry run.");
+            _logger.LogError(e, "Importing Failure: {DestinationImages}", formattedDestinationImages);
+
+            throw;
         }
     }