backend: require confirmation for signed channel updates [CI]

backend/src/MoShiro.Backend.Api/Admin/BuildEndpoints.cs

@@ -1,3 +1,4 @@
+using System.Text.Json;
 using Fleet.Core;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
@@ -21,6 +22,12 @@ public static class BuildEndpoints
             .Api("releases_list", "The latest signed release manifest of each component", Tag).Returns<PageDto<ReleaseDto>>().ProducesProblems(401, 403);
         group.MapPost("/nodes/{id}/update", RequestUpdateAsync)
             .Api("nodes_update", "Ask an online agent or probe to install the release it has been offered", Tag).Returns<object>(StatusCodes.Status204NoContent).ProducesProblems(401, 403, 409);
+        group.MapGet("/backend/update", BackendUpdateAsync)
+            .Api("backend_update_get", "Current channel and host-verified backend update", Tag).Returns<BackendUpdateDto>().ProducesProblems(401, 403);
+        group.MapPost("/backend/update", ConfirmBackendUpdateAsync)
+            .Api("backend_update_confirm", "Confirm one verified backend release before the host restarts it", Tag).Returns<object>(StatusCodes.Status204NoContent).ProducesProblems(400, 401, 403, 412);
+        group.MapGet("/backend/update/live", LiveBackendUpdateAsync)
+            .Api("backend_update_live", "Server-sent backend update notifications", Tag).Produces(StatusCodes.Status200OK, contentType: "text/event-stream").ProducesProblems(401, 403);
     }
 
     /// <summary>登记发布清单：挂在 <see cref="ReleaseGuard"/> 下，除了管理员，CI 用的 <c>release</c> 令牌也能调用（它只能做这一件事）。</summary>
@@ -31,7 +38,7 @@ public static class BuildEndpoints
             .Returns<ReleaseDto>(StatusCodes.Status201Created).ProducesProblems(400, 401, 403, 409);
     }
 
-    private static async Task<IResult> GetAsync(HttpContext http, NodeInfoService nodes, ReleaseService releases, CancellationToken ct)
+    private static async Task<IResult> GetAsync(HttpContext http, NodeInfoService nodes, ReleaseService releases, BackendUpdates backendUpdates, CancellationToken ct)
     {
         var items = (await nodes.ListAsync(ct))
             .OrderBy(n => n.Kind, StringComparer.Ordinal)
@@ -39,7 +46,7 @@ public static class BuildEndpoints
             .Select(n => new NodeBuildDto(n.NodeId, n.Kind, n.Os, n.OsName, n.Arch, n.Version, n.Tag, n.Commit, n.BuiltAt, ToDto(releases.StatusOf(new NodeId(n.NodeId)))))
             .ToList();
         http.Response.Headers.CacheControl = "no-store";
-        return TypedResults.Json(new BuildInfoDto(NodeEndpoints.Backend(withCommit: true), items), ApiJsonContext.Default.BuildInfoDto);
+        return TypedResults.Json(new BuildInfoDto(NodeEndpoints.Backend(withCommit: true), items, ToDto(await backendUpdates.GetAsync(ct))), ApiJsonContext.Default.BuildInfoDto);
     }
 
     private static async Task<IResult> ListReleasesAsync(ReleaseService releases, CancellationToken ct) =>
@@ -56,7 +63,43 @@ public static class BuildEndpoints
     private static async Task<IResult> RequestUpdateAsync(HttpContext http, ReleaseService releases, string id, CancellationToken ct) =>
         await releases.RequestUpdateAsync(new NodeId(id), ct) ? TypedResults.NoContent() : Problems.Create(http, MoShiroErrors.AgentOffline, "the node is not connected");
 
-    private static ReleaseDto ToDto(ReleaseOffer offer) => new(offer.Component, offer.Seq, offer.Tag, offer.Version, offer.Digest);
+    private static ReleaseDto ToDto(ReleaseOffer offer) => new(offer.Component, offer.Seq, offer.Tag, offer.Version, offer.Digest, offer.Channel);
+
+    private static BackendUpdateDto ToDto(BackendUpdateView view) =>
+        new(view.Channel, view.Enabled, view.State, view.CurrentTag, view.CurrentDigest, view.Available is { } release ? ToDto(release) : null, view.Error);
+
+    private static async Task<IResult> BackendUpdateAsync(BackendUpdates updates, CancellationToken ct) =>
+        TypedResults.Json(ToDto(await updates.GetAsync(ct)), ApiJsonContext.Default.BackendUpdateDto);
+
+    private static async Task<IResult> ConfirmBackendUpdateAsync(HttpContext http, BackendUpdates updates, ConfirmBackendUpdateRequest request, CancellationToken ct)
+    {
+        Result<bool> result = await updates.ConfirmAsync(request.Seq, ct);
+        return result.IsSuccess ? TypedResults.NoContent() : Problems.From(http, result.Error);
+    }
+
+    private static async Task LiveBackendUpdateAsync(HttpContext http, BackendUpdates updates, TimeProvider time, CancellationToken ct)
+    {
+        http.Response.ContentType = "text/event-stream";
+        http.Response.Headers.CacheControl = "no-store";
+        http.Response.Headers["X-Accel-Buffering"] = "no";
+        using var timer = new PeriodicTimer(TimeSpan.FromSeconds(2), time);
+        string? previous = null;
+        try
+        {
+            do
+            {
+                string json = JsonSerializer.Serialize(ToDto(await updates.GetAsync(ct)), ApiJsonContext.Default.BackendUpdateDto);
+                await http.Response.WriteAsync(json != previous ? "event: backend_update\ndata: " + json + "\n\n" : ": heartbeat\n\n", ct);
+                await http.Response.Body.FlushAsync(ct);
+                previous = json;
+            }
+            while (await timer.WaitForNextTickAsync(ct));
+        }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            // 浏览器断开或后端正在升级重启
+        }
+    }
 
     private static NodeUpdateDto? ToDto(UpdateStatus? status) =>
         status is null ? null : new NodeUpdateDto(status.State, status.Current, status.Available?.Tag, status.Available?.Version, status.Error, status.At > 0 ? DateTimeOffset.FromUnixTimeSeconds(status.At) : null);