Advertise docs-builder updates when running from command line (#276)

* Advertise docs-builder updates when running from the command line

* Advertise at the end of command invocation

* remove up to date message

* include installation documentation in the output

src/docs-builder/Cli/CheckForUpdatesFilter.cs

@@ -0,0 +1,95 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Reflection;
+using ConsoleAppFramework;
+using Elastic.Markdown.Helpers;
+
+namespace Documentation.Builder.Cli;
+
+internal class CheckForUpdatesFilter : ConsoleAppFilter
+{
+	private readonly FileInfo _stateFile;
+
+	public CheckForUpdatesFilter(ConsoleAppFilter next) : base(next)
+	{
+		// ~/Library/Application\ Support/ on osx
+		// XDG_DATA_HOME or home/.local/share on linux
+		// %LOCAL_APPLICATION_DATA% windows
+		var localPath = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+		var elasticPath = Path.Combine(localPath, "elastic");
+		_stateFile = new FileInfo(Path.Combine(elasticPath, "docs-build-check.state"));
+	}
+
+	public override async Task InvokeAsync(ConsoleAppContext context, Cancel ctx)
+	{
+		await Next.InvokeAsync(context, ctx);
+		var latestVersionUrl = await GetLatestVersion(ctx);
+		if (latestVersionUrl is null)
+			ConsoleApp.LogError("Unable to determine latest version");
+		else
+			CompareWithAssemblyVersion(latestVersionUrl);
+	}
+
+	private void CompareWithAssemblyVersion(Uri latestVersionUrl)
+	{
+		var versionPath = latestVersionUrl.AbsolutePath.Split('/').Last();
+		if (!SemVersion.TryParse(versionPath, out var latestVersion))
+		{
+			ConsoleApp.LogError($"Unable to parse latest version from {latestVersionUrl}");
+			return;
+		}
+
+		var assemblyVersion = Assembly.GetExecutingAssembly().GetCustomAttributes<AssemblyInformationalVersionAttribute>()
+			.FirstOrDefault()?.InformationalVersion;
+		if (SemVersion.TryParse(assemblyVersion ?? "", out var currentSemVersion))
+		{
+			if (latestVersion <= currentSemVersion)
+				return;
+			ConsoleApp.Log("");
+			ConsoleApp.Log($"A new version of docs-builder is available: {latestVersion} currently on version {currentSemVersion}");
+			ConsoleApp.Log("");
+			ConsoleApp.Log($"	{latestVersionUrl}");
+			ConsoleApp.Log("");
+			ConsoleApp.Log("Read more about updating here:");
+			ConsoleApp.Log("	https://elastic.github.io/docs-builder/contribute/locally.html#step-one	");
+			ConsoleApp.Log("");
+			return;
+		}
+
+		ConsoleApp.LogError($"Unable to parse current version from docs-builder binary");
+	}
+
+	private async ValueTask<Uri?> GetLatestVersion(CancellationToken ctx)
+	{
+		if (!string.IsNullOrEmpty(Environment.GetEnvironmentVariable("CI")))
+			return null;
+
+		// only check for new versions once per hour
+		if (_stateFile.Exists && _stateFile.LastWriteTimeUtc >= DateTime.UtcNow.Subtract(TimeSpan.FromHours(1)))
+		{
+			var url = await File.ReadAllTextAsync(_stateFile.FullName, ctx);
+			if (Uri.TryCreate(url, UriKind.Absolute, out var uri))
+				return uri;
+		}
+
+		try
+		{
+			var httpClient = new HttpClient(new HttpClientHandler { AllowAutoRedirect = false });
+			var response = await httpClient.GetAsync("https://github.com/elastic/docs-builder/releases/latest", ctx);
+			var redirectUrl = response.Headers.Location;
+			if (redirectUrl is not null && _stateFile.Directory is not null)
+			{
+				// ensure the 'elastic' folder exists.
+				if (!Directory.Exists(_stateFile.Directory.FullName))
+					Directory.CreateDirectory(_stateFile.Directory.FullName);
+				await File.WriteAllTextAsync(_stateFile.FullName, redirectUrl.ToString(), ctx);
+			}
+			return redirectUrl;
+		}
+		// ReSharper disable once RedundantEmptyFinallyBlock
+		// ignore on purpose
+		finally { }
+	}
+}

src/docs-builder/Cli/Commands.cs

@@ -25,6 +25,7 @@ internal class Commands(ILoggerFactory logger, ICoreService githubActionsService
 	/// <param name="port">Port to serve the documentation.</param>
 	/// <param name="ctx"></param>
 	[Command("serve")]
+	[ConsoleAppFilter<CheckForUpdatesFilter>]
 	public async Task Serve(string? path = null, int port = 3000, Cancel ctx = default)
 	{
 		var host = new DocumentationWebHost(path, port, logger, new FileSystem());
@@ -45,6 +46,7 @@ public async Task Serve(string? path = null, int port = 3000, Cancel ctx = defau
 	[Command("generate")]
 	[ConsoleAppFilter<StopwatchFilter>]
 	[ConsoleAppFilter<CatchExceptionFilter>]
+	[ConsoleAppFilter<CheckForUpdatesFilter>]
 	public async Task<int> Generate(
 		string? path = null,
 		string? output = null,
@@ -89,6 +91,7 @@ public async Task<int> Generate(
 	[Command("")]
 	[ConsoleAppFilter<StopwatchFilter>]
 	[ConsoleAppFilter<CatchExceptionFilter>]
+	[ConsoleAppFilter<CheckForUpdatesFilter>]
 	public async Task<int> GenerateDefault(
 		string? path = null,
 		string? output = null,

src/docs-builder/Program.cs

@@ -27,10 +27,10 @@
 services.AddSingleton<DiagnosticsChannel>();
 services.AddSingleton<DiagnosticsCollector>();
 
-
 await using var serviceProvider = services.BuildServiceProvider();
 var logger = serviceProvider.GetRequiredService<ILogger<Program>>();
 ConsoleApp.ServiceProvider = serviceProvider;
+
 var isHelp = args.Contains("-h") || args.Contains("--help");
 if (!isHelp)
 	ConsoleApp.Log = msg => logger.LogInformation(msg);