Add support for custom Docker registries (#275)

* Add support for custom Docker registries

This allows a user to set the `CONTAINER_REGISTRY` environment variable
which can be used in place of the default of ghcr.io if a customer would
like to mirror our image so they can self host behind any proxies or other
custom network stack.

* Add details to README about a custom docker registry

README.md

@@ -48,12 +48,21 @@ In order for GitHub Actions Importer to communicate with your current CI/CD serv
 
 ```bash
 $ gh actions-importer configure
-? Enter value for 'GITHUB_ACCESS_TOKEN' (leave empty to skip): 
+? Enter value for 'GITHUB_ACCESS_TOKEN' (leave empty to skip):
 ...
 ```
 
 You can find detailed information about using environment variables in the platform-specific documentation.
 
+#### Using a custom Docker registry
+
+We highly recommend using the [official GitHub Container Registry to pull the GitHub Actions Importer Docker image](https://github.com/actions-importer/preview/pkgs/container/cli/). However, if you need to use a custom Docker registry, you can configure GitHub Actions Importer to use a custom Docker registry by setting the `CONTAINER_REGISTRY` environment variable in your `.env.local` file.
+
+```bash
+# .env.local
+CONTAINER_REGISTRY=my-custom-registry.com
+```
+
 ### Documentation
 
 Detailed information about how to use GitHub Actions Importer can be found in the [documentation](https://docs.github.com/en/actions/migrating-to-github-actions/automating-migration-with-github-actions-importer).
@@ -70,7 +79,7 @@ You can access recorded demos of GitHub Actions Importer performing migrations t
 
 ### Self-guided learning
 
-The GitHub Actions Importer labs repository contains platform-specific learning paths that teach you how to use GitHub Actions Importer and how to approach migrations to GitHub Actions. To learn more, see the [GitHub Actions Importer labs repository](https://github.com/actions/importer-labs/tree/main#readme).  
+The GitHub Actions Importer labs repository contains platform-specific learning paths that teach you how to use GitHub Actions Importer and how to approach migrations to GitHub Actions. To learn more, see the [GitHub Actions Importer labs repository](https://github.com/actions/importer-labs/tree/main#readme).
 
 ## Product roadmap
 

src/ActionsImporter.UnitTests/AppTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Immutable;
 using System.IO;
 using System.Threading.Tasks;
 using ActionsImporter.Interfaces;
@@ -24,7 +25,7 @@ public void BeforeEachTest()
         _dockerService = new Mock<IDockerService>();
         _processService = new Mock<IProcessService>();
         _configurationService = new Mock<IConfigurationService>();
-        _app = new App(_dockerService.Object, _processService.Object, _configurationService.Object);
+        _app = new App(_dockerService.Object, _processService.Object, _configurationService.Object, ImmutableDictionary<string, string>.Empty);
         _out = Console.Out;
     }
 

src/ActionsImporter/App.cs

@@ -7,7 +7,6 @@ namespace ActionsImporter;
 public class App
 {
     private const string ActionsImporterImage = "actions-importer/cli";
-    private const string ActionsImporterContainerRegistry = "ghcr.io";
 
     private readonly IDockerService _dockerService;
     private readonly IProcessService _processService;
@@ -16,15 +15,19 @@ public class App
     public bool IsPrerelease { get; set; }
     public bool NoHostNetwork { get; set; }
 
+    private readonly ImmutableDictionary<string, string> _environmentVariables;
     private string ImageTag => IsPrerelease ? "pre" : "latest";
 
     private string ImageName => $"{ActionsImporterImage}:{ImageTag}";
+    private readonly string ActionsImporterContainerRegistry;
 
-    public App(IDockerService dockerService, IProcessService processService, IConfigurationService configurationService)
+    public App(IDockerService dockerService, IProcessService processService, IConfigurationService configurationService, ImmutableDictionary<string, string> environmentVariables)
     {
         _dockerService = dockerService;
         _processService = processService;
         _configurationService = configurationService;
+        _environmentVariables = environmentVariables;
+        ActionsImporterContainerRegistry = _environmentVariables.TryGetValue("CONTAINER_REGISTRY", out var registry) ? registry : "ghcr.io";
     }
 
     public async Task<int> UpdateActionsImporterAsync()
@@ -104,7 +107,6 @@ public async Task CheckForUpdatesAsync()
 
     public async Task<int> ConfigureAsync(string[] args)
     {
-        var currentVariables = await _configurationService.ReadCurrentVariablesAsync().ConfigureAwait(false);
         ImmutableDictionary<string, string>? newVariables;
 
         if (args.Contains($"--{Commands.Configure.OptionalFeaturesOption.Name}"))
@@ -126,7 +128,7 @@ public async Task<int> ConfigureAsync(string[] args)
             newVariables = _configurationService.GetUserInput();
         }
 
-        var mergedVariables = _configurationService.MergeVariables(currentVariables, newVariables);
+        var mergedVariables = _configurationService.MergeVariables(_environmentVariables, newVariables);
         await _configurationService.WriteVariablesAsync(mergedVariables);
 
         await Console.Out.WriteLineAsync("Environment variables successfully updated.");

src/ActionsImporter/Program.cs

@@ -9,11 +9,13 @@
 using Version = ActionsImporter.Commands.Version;
 
 var processService = new ProcessService();
+var configurationService = new ConfigurationService();
 
 var app = new App(
     new DockerService(processService, new RuntimeService()),
     processService,
-    new ConfigurationService()
+    new ConfigurationService(),
+    await configurationService.ReadCurrentVariablesAsync()
 );
 
 string welcomeMessage = @"GitHub Actions Importer helps you plan, test, and automate your migration to GitHub Actions.