Updated EllieBot.Coordinator

EllieBot.sln

@@ -17,7 +17,11 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "EllieBot", "src\EllieBot\El
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "ayu", "ayu", "{872A4C63-833C-4AE0-91AB-3CE348D3E6F8}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ayu.Discord.Voice", "src\ayu\Ayu.Discord.Voice\Ayu.Discord.Voice.csproj", "{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Ayu.Discord.Voice", "src\ayu\Ayu.Discord.Voice\Ayu.Discord.Voice.csproj", "{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "EllieBot.Tests", "src\EllieBot.Tests\EllieBot.Tests.csproj", "{179DF3B3-AD32-4335-8231-9818338DF3A2}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EllieBot.Coordinator", "src\EllieBot.Coordinator\EllieBot.Coordinator.csproj", "{A631DDF0-3AD1-4CB9-8458-314B1320868A}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -33,6 +37,14 @@ Global
 		{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067}.Release|Any CPU.Build.0 = Release|Any CPU
+		{179DF3B3-AD32-4335-8231-9818338DF3A2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{179DF3B3-AD32-4335-8231-9818338DF3A2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{179DF3B3-AD32-4335-8231-9818338DF3A2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{179DF3B3-AD32-4335-8231-9818338DF3A2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A631DDF0-3AD1-4CB9-8458-314B1320868A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A631DDF0-3AD1-4CB9-8458-314B1320868A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A631DDF0-3AD1-4CB9-8458-314B1320868A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A631DDF0-3AD1-4CB9-8458-314B1320868A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -41,6 +53,8 @@ Global
 		{BCB21472-84D2-4B63-B5DD-31E6A3EC9791} = {B28FB883-9688-41EB-BF5A-945F4A4EB628}
 		{872A4C63-833C-4AE0-91AB-3CE348D3E6F8} = {B28FB883-9688-41EB-BF5A-945F4A4EB628}
 		{5AD2EFFB-7774-49B2-A791-3BAC4DAEE067} = {872A4C63-833C-4AE0-91AB-3CE348D3E6F8}
+		{179DF3B3-AD32-4335-8231-9818338DF3A2} = {B28FB883-9688-41EB-BF5A-945F4A4EB628}
+		{A631DDF0-3AD1-4CB9-8458-314B1320868A} = {B28FB883-9688-41EB-BF5A-945F4A4EB628}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {79F61C2C-CDBB-4361-A234-91A0B334CFE4}

TODO.md

@@ -1,3 +1,4 @@
 # List of things to do
 
  - Finish the full system rewrite
+ - Finish the EllieBot.Tests project

src/EllieBot.Coordinator/CoordStartup.cs

@@ -0,0 +1,47 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+namespace EllieBot.Coordinator
+{
+    public class CoordStartup
+    {
+        public IConfiguration Configuration { get; }
+
+        public CoordStartup(IConfiguration config)
+            => Configuration = config;
+
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services.AddGrpc();
+            services.AddSingleton<CoordinatorRunner>();
+            services.AddSingleton<IHostedService, CoordinatorRunner>(
+                serviceProvider => serviceProvider.GetRequiredService<CoordinatorRunner>());
+        }
+
+        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
+        {
+            if (env.IsDevelopment())
+            {
+                app.UseDeveloperExceptionPage();
+            }
+
+            app.UseRouting();
+
+            app.UseEndpoints(endpoints =>
+            {
+                endpoints.MapGrpcService<CoordinatorService>();
+
+                endpoints.MapGet("/",
+                    async context =>
+                    {
+                        await context.Response.WriteAsync(
+                            "Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");
+                    });
+            });
+        }
+    }
+}

src/EllieBot.Coordinator/EllieBot.Coordinator.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+  
+  <ItemGroup>
+    <Protobuf Include="Protos\coordinator.proto" GrpcServices="Server" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Grpc.AspNetCore" Version="2.47.0" />
+    <PackageReference Include="Serilog" Version="2.11.0" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="4.0.1" />
+    <PackageReference Include="Serilog.Sinks.File" Version="5.0.0" />
+    <PackageReference Include="YamlDotNet" Version="11.2.1" />
+  </ItemGroup>
+
+</Project>

src/EllieBot.Coordinator/LogSetup.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Text;
+using Serilog;
+using Serilog.Events;
+using Serilog.Sinks.SystemConsole.Themes;
+
+namespace EllieBot.Services
+{
+    public static class LogSetup
+    {
+        public static void SetupLogger(object source)
+        {
+            Log.Logger = new LoggerConfiguration()
+                .MinimumLevel.Override("Microsoft", LogEventLevel.Information)
+                .MinimumLevel.Override("System", LogEventLevel.Information)
+                .MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Warning)
+                .Enrich.FromLogContext()
+                .WriteTo.File("coord.log", LogEventLevel.Information,
+                    rollOnFileSizeLimit: true,
+                    fileSizeLimitBytes: 10_000_000)
+                .WriteTo.Console(LogEventLevel.Information,
+                    theme: GetTheme(),
+                    outputTemplate: "[{Timestamp:HH:mm:ss} {Level:u3}] | #{LogSource} | {Message:lj}{NewLine}{Exception}")
+                .Enrich.WithProperty("LogSource", source)
+                .CreateLogger();
+
+            Console.OutputEncoding = Encoding.UTF8;
+        }
+
+        private static ConsoleTheme GetTheme()
+        {
+            if (Environment.OSVersion.Platform == PlatformID.Unix)
+                return AnsiConsoleTheme.Code;
+
+
+#if DEBUG
+            return AnsiConsoleTheme.Code;
+#else
+            return ConsoleTheme.None;
+#endif
+        }
+    }
+}

src/EllieBot.Coordinator/Program.cs

@@ -0,0 +1,20 @@
+using System;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Hosting;
+using EllieBot.Coordinator;
+using EllieBot.Services;
+using Serilog;
+
+// Additional configuration is required to successfully run gRPC on macOS.
+// For instructions on how to configure Kestrel and gRPC clients on macOS, visit https://go.microsoft.com/fwlink/?linkid=2099682
+static IHostBuilder CreateHostBuilder(string[] args) =>
+    Host.CreateDefaultBuilder(args)
+        .ConfigureWebHostDefaults(webBuilder =>
+        {
+            webBuilder.UseStartup<CoordStartup>();
+        });
+
+LogSetup.SetupLogger("coord");
+Log.Information("Starting coordinator... Pid: {ProcessId}", Environment.ProcessId);
+
+CreateHostBuilder(args).Build().Run();

src/EllieBot.Coordinator/Properties/launchSettings.json

@@ -0,0 +1,13 @@
+{
+  "profiles": {
+    "EllieBot.Coordinator": {
+      "commandName": "Project",
+      "dotnetRunMessages": "true",
+      "launchBrowser": false,
+      "applicationUrl": "http://localhost:3442;https://localhost:3443",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/EllieBot.Coordinator/Protos/coordinator.proto

@@ -0,0 +1,127 @@
+syntax = "proto3";
+import "google/protobuf/timestamp.proto";
+
+option csharp_namespace = "EllieBot.Coordinator";
+
+package elliebot;
+
+service Coordinator {
+  // sends update to coordinator to let it know that the shard is alive
+  rpc Heartbeat(HeartbeatRequest) returns (HeartbeatReply);
+  // restarts a shard given the id
+  rpc RestartShard(RestartShardRequest) returns (RestartShardReply);
+  // reshards given the new number of shards
+  rpc Reshard(ReshardRequest) returns (ReshardReply);
+  // Reload config
+  rpc Reload(ReloadRequest) returns (ReloadReply);
+  // Gets status of a single shard
+  rpc GetStatus(GetStatusRequest) returns (GetStatusReply);
+  // Get status of all shards
+  rpc GetAllStatuses(GetAllStatusesRequest) returns (GetAllStatusesReply);
+  // Restarts all shards. Queues them to be restarted at a normal rate. Setting Nuke to true will kill all shards right
+  // away
+  rpc RestartAllShards(RestartAllRequest) returns (RestartAllReply);
+  
+  // kill coordinator (and all shards as a consequence)
+  rpc Die(DieRequest) returns (DieReply);
+  
+  rpc SetConfigText(SetConfigTextRequest) returns (SetConfigTextReply);
+  
+  rpc GetConfigText(GetConfigTextRequest) returns (GetConfigTextReply);
+}
+
+enum ConnState {
+  Disconnected = 0;
+  Connecting = 1;
+  Connected = 2;
+}
+
+message HeartbeatRequest {
+  int32 shardId = 1;
+  int32 guildCount = 2;  
+  ConnState state = 3;
+}
+
+message HeartbeatReply {
+  bool gracefulImminent = 1;
+}
+
+message RestartShardRequest {
+  int32 shardId = 1;
+  // should it be queued for restart, set false to kill it and restart immediately with priority
+  bool queue = 2;
+}
+
+message RestartShardReply {
+  
+}
+
+message ReshardRequest {
+  int32 shards = 1;
+}
+
+message ReshardReply {
+  
+}
+
+message ReloadRequest {
+  
+}
+
+message ReloadReply {
+  
+}
+
+message GetStatusRequest {
+ int32 shardId = 1; 
+}
+
+message GetStatusReply {
+  int32 shardId = 1;
+  ConnState state = 2;
+  int32 guildCount = 3;
+  google.protobuf.Timestamp lastUpdate = 4;
+  bool scheduledForRestart = 5;
+  google.protobuf.Timestamp startedAt = 6;
+}
+
+message GetAllStatusesRequest {
+  
+}
+
+message GetAllStatusesReply {
+	repeated GetStatusReply Statuses = 1;
+}
+
+message RestartAllRequest {
+  bool nuke = 1;
+}
+
+message RestartAllReply {
+  
+}
+
+message DieRequest {
+  bool graceful = 1;
+}
+
+message DieReply {
+  
+}
+
+message GetConfigTextRequest {
+  
+}
+
+message GetConfigTextReply {
+  string configYml = 1;
+}
+
+message SetConfigTextRequest {
+  string configYml = 1;
+}
+
+message SetConfigTextReply {
+  bool success = 1;
+  string error = 2;
+}

src/EllieBot.Coordinator/README.md

@@ -0,0 +1,11 @@
+# Coordinator project
+
+Grpc-based coordinator useful for sharded EllieBot. Its purpose is controlling the lifetime and checking status of the shards it creates.
+
+### Supports
+
+- Checking status
+- Individual shard restarts
+- Full shard restarts
+- Graceful coordinator restarts (restart/update coordinator without killing shards)
+- Kill/Stop

src/EllieBot.Coordinator/Services/CoordinatorRunner.cs

@@ -0,0 +1,457 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Hosting;
+using Serilog;
+using YamlDotNet.Serialization;
+
+namespace EllieBot.Coordinator
+{
+    public sealed class CoordinatorRunner : BackgroundService
+    {
+        private const string CONFIG_PATH = "coord.yml";
+
+        private const string GRACEFUL_STATE_PATH = "graceful.json";
+        private const string GRACEFUL_STATE_BACKUP_PATH = "graceful_old.json";
+
+        private readonly Serializer _serializer;
+        private readonly Deserializer _deserializer;
+
+        private Config _config;
+        private ShardStatus[] _shardStatuses;
+
+        private readonly object locker = new object();
+        private readonly Random _rng;
+        private bool _gracefulImminent;
+
+        public CoordinatorRunner()
+        {
+            _serializer = new();
+            _deserializer = new();
+            _config = LoadConfig();
+            _rng = new Random();
+
+            if (!TryRestoreOldState())
+                InitAll();
+        }
+
+        private Config LoadConfig()
+        {
+            lock (locker)
+            {
+                return _deserializer.Deserialize<Config>(File.ReadAllText(CONFIG_PATH));
+            }
+        }
+
+        private void SaveConfig(in Config config)
+        {
+            lock (locker)
+            {
+                var output = _serializer.Serialize(config);
+                File.WriteAllText(CONFIG_PATH, output);
+            }
+        }
+
+        public void ReloadConfig()
+        {
+            lock (locker)
+            {
+                var oldConfig = _config;
+                var newConfig = LoadConfig();
+                if (oldConfig.TotalShards != newConfig.TotalShards)
+                {
+                    KillAll();
+                }
+                _config = newConfig;
+                if (oldConfig.TotalShards != newConfig.TotalShards)
+                {
+                    InitAll();
+                }
+            }
+        }
+
+        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+        {
+            // Log.Information("Executing");
+
+            bool first = true;
+            while (!stoppingToken.IsCancellationRequested)
+            {
+                try
+                {
+                    bool hadAction = false;
+                    lock (locker)
+                    {
+                        var shardIds = Enumerable.Range(0, 1) // shard 0 is always first
+                            .Append((int)((1173494918812024863 >> 22) % _config.TotalShards)) // then ellie server shard
+                            .Concat(Enumerable.Range(1, _config.TotalShards - 1)
+                                .OrderBy(_ => _rng.Next())) // then all other shards in a random order
+                            .Distinct()
+                            .ToList();
+
+                        if (first)
+                        {
+                            // Log.Information("Startup order: {StartupOrder}",string.Join(' ', shardIds));
+                            first = false;
+                        }
+
+                        foreach (var shardId in shardIds)
+                        {
+                            if (stoppingToken.IsCancellationRequested)
+                                break;
+
+                            var status = _shardStatuses[shardId];
+
+                            if (status.ShouldRestart)
+                            {
+                                Log.Warning("Shard {ShardId} is restarting (scheduled)...", shardId);
+                                hadAction = true;
+                                StartShard(shardId);
+                                break;
+                            }
+
+                            if (DateTime.UtcNow - status.LastUpdate >
+                                TimeSpan.FromSeconds(_config.UnresponsiveSec))
+                            {
+                                Log.Warning("Shard {ShardId} is restarting (unresponsive)...", shardId);
+                                hadAction = true;
+                                StartShard(shardId);
+                                break;
+                            }
+
+                            if (status.StateCounter > 8 && status.State != ConnState.Connected)
+                            {
+                                Log.Warning("Shard {ShardId} is restarting (stuck)...", shardId);
+                                hadAction = true;
+                                StartShard(shardId);
+                                break;
+                            }
+
+                            try
+                            {
+                                if (status.Process is null or { HasExited: true })
+                                {
+                                    Log.Warning("Shard {ShardId} is starting (process)...", shardId);
+                                    hadAction = true;
+                                    StartShard(shardId);
+                                    break;
+                                }
+                            }
+                            catch (InvalidOperationException)
+                            {
+                                Log.Warning("Process for shard {ShardId} is bugged... ", shardId);
+                                hadAction = true;
+                                StartShard(shardId);
+                                break;
+                            }
+                        }
+                    }
+
+                    if (hadAction)
+                    {
+                        await Task.Delay(_config.RecheckIntervalMs, stoppingToken).ConfigureAwait(false);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Log.Error(ex, "Error in coordinator: {Message}", ex.Message);
+                }
+
+                await Task.Delay(5000, stoppingToken).ConfigureAwait(false);
+            }
+        }
+
+        private void StartShard(int shardId)
+        {
+            var status = _shardStatuses[shardId];
+            try
+            {
+                status.Process?.Kill(true);
+            }
+            catch
+            {
+            }
+            try
+            {
+                status.Process?.Dispose();
+            }
+            catch
+            {
+            }
+
+            var proc = StartShardProcess(shardId);
+            _shardStatuses[shardId] = status with
+            {
+                Process = proc,
+                LastUpdate = DateTime.UtcNow,
+                State = ConnState.Disconnected,
+                ShouldRestart = false,
+                StateCounter = 0,
+            };
+        }
+
+        private Process StartShardProcess(int shardId)
+            => Process.Start(new ProcessStartInfo()
+            {
+                FileName = _config.ShardStartCommand,
+                Arguments = string.Format(_config.ShardStartArgs,
+                    shardId,
+                    _config.TotalShards),
+                EnvironmentVariables =
+                {
+                    {"ELLIEBOT_IS_COORDINATED", "1"}
+                }
+                // CreateNoWindow = true,
+                // UseShellExecute = false,
+            });
+
+        public bool Heartbeat(int shardId, int guildCount, ConnState state)
+        {
+            lock (locker)
+            {
+                if (shardId >= _shardStatuses.Length)
+                    throw new ArgumentOutOfRangeException(nameof(shardId));
+
+                var status = _shardStatuses[shardId];
+                status = _shardStatuses[shardId] = status with
+                {
+                    GuildCount = guildCount,
+                    State = state,
+                    LastUpdate = DateTime.UtcNow,
+                    StateCounter = status.State == state
+                        ? status.StateCounter + 1
+                        : 1
+                };
+                if (status.StateCounter > 1 && status.State == ConnState.Disconnected)
+                {
+                    Log.Warning("Shard {ShardId} is in DISCONNECTED state! ({StateCounter})",
+                        status.ShardId,
+                        status.StateCounter);
+                }
+
+                return _gracefulImminent;
+            }
+        }
+
+        public void SetShardCount(int totalShards)
+        {
+            lock (locker)
+            {
+                SaveConfig(new Config(
+                    totalShards,
+                    _config.RecheckIntervalMs,
+                    _config.ShardStartCommand,
+                    _config.ShardStartArgs,
+                    _config.UnresponsiveSec));
+            }
+        }
+
+        public void RestartShard(int shardId, bool queue)
+        {
+            lock (locker)
+            {
+                if (shardId >= _shardStatuses.Length)
+                    throw new ArgumentOutOfRangeException(nameof(shardId));
+
+                _shardStatuses[shardId] = _shardStatuses[shardId] with
+                {
+                    ShouldRestart = true,
+                    StateCounter = 0,
+                };
+            }
+        }
+
+        public void RestartAll(bool nuke)
+        {
+            lock (locker)
+            {
+                if (nuke)
+                {
+                    KillAll();
+                }
+
+                QueueAll();
+            }
+        }
+
+        private void KillAll()
+        {
+            lock (locker)
+            {
+                for (var shardId = 0; shardId < _shardStatuses.Length; shardId++)
+                {
+                    var status = _shardStatuses[shardId];
+                    if (status.Process is Process p)
+                    {
+                        try { p.Kill(); } catch { }
+                        try { p.Dispose(); } catch { }
+                        _shardStatuses[shardId] = status with
+                        {
+                            Process = null,
+                            ShouldRestart = true,
+                            LastUpdate = DateTime.UtcNow,
+                            State = ConnState.Disconnected,
+                            StateCounter = 0,
+                        };
+                    }
+                }
+            }
+        }
+
+        public void SaveState()
+        {
+            var coordState = new CoordState()
+            {
+                StatusObjects = _shardStatuses
+                    .Select(x => new JsonStatusObject()
+                    {
+                        Pid = x.Process?.Id,
+                        ConnectionState = x.State,
+                        GuildCount = x.GuildCount,
+                    })
+                    .ToList()
+            };
+            var jsonState = JsonSerializer.Serialize(coordState, new JsonSerializerOptions()
+            {
+                WriteIndented = true,
+            });
+            File.WriteAllText(GRACEFUL_STATE_PATH, jsonState);
+        }
+        private bool TryRestoreOldState()
+        {
+            lock (locker)
+            {
+                if (!File.Exists(GRACEFUL_STATE_PATH))
+                    return false;
+
+                Log.Information("Restoring old coordinator state...");
+
+                CoordState savedState;
+                try
+                {
+                    savedState = JsonSerializer.Deserialize<CoordState>(File.ReadAllText(GRACEFUL_STATE_PATH));
+
+                    if (savedState is null)
+                        throw new Exception("Old state is null?!");
+                }
+                catch (Exception ex)
+                {
+                    Log.Error(ex, "Error deserializing old state: {Message}", ex.Message);
+                    File.Move(GRACEFUL_STATE_PATH, GRACEFUL_STATE_BACKUP_PATH, overwrite: true);
+                    return false;
+                }
+
+                if (savedState.StatusObjects.Count != _config.TotalShards)
+                {
+                    Log.Error("Unable to restore old state because shard count doesn't match");
+                    File.Move(GRACEFUL_STATE_PATH, GRACEFUL_STATE_BACKUP_PATH, overwrite: true);
+                    return false;
+                }
+
+                _shardStatuses = new ShardStatus[_config.TotalShards];
+
+                for (int shardId = 0; shardId < _shardStatuses.Length; shardId++)
+                {
+                    var statusObj = savedState.StatusObjects[shardId];
+                    Process p = null;
+                    if (statusObj.Pid is { } pid)
+                    {
+                        try
+                        {
+                            p = Process.GetProcessById(pid);
+                        }
+                        catch (Exception ex)
+                        {
+                            Log.Warning(ex, "Process for shard {ShardId} is not runnning", shardId);
+                        }
+                    }
+
+                    _shardStatuses[shardId] = new(
+                        shardId,
+                        DateTime.UtcNow,
+                        statusObj.GuildCount,
+                        statusObj.ConnectionState,
+                        p is null,
+                        p);
+                }
+
+                File.Move(GRACEFUL_STATE_PATH, GRACEFUL_STATE_BACKUP_PATH, overwrite: true);
+                Log.Information("Old state restored!");
+                return true;
+            }
+        }
+
+        private void InitAll()
+        {
+            lock (locker)
+            {
+                _shardStatuses = new ShardStatus[_config.TotalShards];
+                for (var shardId = 0; shardId < _shardStatuses.Length; shardId++)
+                {
+                    _shardStatuses[shardId] = new ShardStatus(shardId, DateTime.UtcNow);
+                }
+            }
+        }
+
+        private void QueueAll()
+        {
+            lock (locker)
+            {
+                for (var shardId = 0; shardId < _shardStatuses.Length; shardId++)
+                {
+                    _shardStatuses[shardId] = _shardStatuses[shardId] with
+                    {
+                        ShouldRestart = true
+                    };
+                }
+            }
+        }
+
+
+        public ShardStatus GetShardStatus(int shardId)
+        {
+            lock (locker)
+            {
+                if (shardId >= _shardStatuses.Length)
+                    throw new ArgumentOutOfRangeException(nameof(shardId));
+
+                return _shardStatuses[shardId];
+            }
+        }
+
+        public List<ShardStatus> GetAllStatuses()
+        {
+            lock (locker)
+            {
+                var toReturn = new List<ShardStatus>(_shardStatuses.Length);
+                toReturn.AddRange(_shardStatuses);
+                return toReturn;
+            }
+        }
+
+        public void PrepareGracefulShutdown()
+        {
+            lock (locker)
+            {
+                _gracefulImminent = true;
+            }
+        }
+
+        public string GetConfigText()
+            => File.ReadAllText(CONFIG_PATH);
+
+        public void SetConfigText(string text)
+        {
+            if (string.IsNullOrWhiteSpace(text))
+                throw new ArgumentNullException(nameof(text), "coord.yml can't be empty");
+            var config = _deserializer.Deserialize<Config>(text);
+            SaveConfig(in config);
+            ReloadConfig();
+        }
+    }
+}

src/EllieBot.Coordinator/Services/CoordinatorService.cs

@@ -0,0 +1,144 @@
+using System;
+using System.Threading.Tasks;
+using Google.Protobuf.WellKnownTypes;
+using Grpc.Core;
+
+namespace EllieBot.Coordinator
+{
+    public sealed class CoordinatorService : Coordinator.CoordinatorBase
+    {
+        private readonly CoordinatorRunner _runner;
+
+        public CoordinatorService(CoordinatorRunner runner)
+            => _runner = runner;
+
+        public override Task<HeartbeatReply> Heartbeat(HeartbeatRequest request, ServerCallContext context)
+        {
+            var gracefulImminent = _runner.Heartbeat(request.ShardId, request.GuildCount, request.State);
+            return Task.FromResult(new HeartbeatReply()
+            {
+                GracefulImminent = gracefulImminent
+            });
+        }
+
+        public override Task<ReshardReply> Reshard(ReshardRequest request, ServerCallContext context)
+        {
+            _runner.SetShardCount(request.Shards);
+            return Task.FromResult(new ReshardReply());
+        }
+
+        public override Task<RestartShardReply> RestartShard(RestartShardRequest request, ServerCallContext context)
+        {
+            _runner.RestartShard(request.ShardId, request.Queue);
+            return Task.FromResult(new RestartShardReply());
+        }
+
+        public override Task<ReloadReply> Reload(ReloadRequest request, ServerCallContext context)
+        {
+            _runner.ReloadConfig();
+            return Task.FromResult(new ReloadReply());
+        }
+
+        public override Task<GetStatusReply> GetStatus(GetStatusRequest request, ServerCallContext context)
+        {
+            var status = _runner.GetShardStatus(request.ShardId);
+
+
+            return Task.FromResult(StatusToStatusReply(status));
+        }
+
+        public override Task<GetAllStatusesReply> GetAllStatuses(GetAllStatusesRequest request,
+            ServerCallContext context)
+        {
+            var statuses = _runner
+                .GetAllStatuses();
+
+            var reply = new GetAllStatusesReply();
+            foreach (var status in statuses)
+                reply.Statuses.Add(StatusToStatusReply(status));
+
+            return Task.FromResult(reply);
+        }
+
+        private static GetStatusReply StatusToStatusReply(ShardStatus status)
+        {
+            DateTime startTime;
+            try
+            {
+                startTime = status.Process is null or { HasExited: true }
+                    ? DateTime.MinValue.ToUniversalTime()
+                    : status.Process.StartTime.ToUniversalTime();
+            }
+            catch
+            {
+                startTime = DateTime.MinValue.ToUniversalTime();
+            }
+
+            var reply = new GetStatusReply()
+            {
+                State = status.State,
+                GuildCount = status.GuildCount,
+                ShardId = status.ShardId,
+                LastUpdate = Timestamp.FromDateTime(status.LastUpdate),
+                ScheduledForRestart = status.ShouldRestart,
+                StartedAt = Timestamp.FromDateTime(startTime)
+            };
+
+            return reply;
+        }
+
+        public override Task<RestartAllReply> RestartAllShards(RestartAllRequest request, ServerCallContext context)
+        {
+            _runner.RestartAll(request.Nuke);
+            return Task.FromResult(new RestartAllReply());
+        }
+
+        public override async Task<DieReply> Die(DieRequest request, ServerCallContext context)
+        {
+            if (request.Graceful)
+            {
+                _runner.PrepareGracefulShutdown();
+                await Task.Delay(10_000);
+            }
+
+            _runner.SaveState();
+            _ = Task.Run(async () =>
+            {
+                await Task.Delay(250);
+                Environment.Exit(0);
+            });
+
+            return new DieReply();
+        }
+
+        public override Task<SetConfigTextReply> SetConfigText(SetConfigTextRequest request, ServerCallContext context)
+        {
+            var error = string.Empty;
+            var success = true;
+            try
+            {
+                _runner.SetConfigText(request.ConfigYml);
+            }
+            catch (Exception ex)
+            {
+                error = ex.Message;
+                success = false;
+            }
+
+            return Task.FromResult<SetConfigTextReply>(new(new()
+            {
+                Success = success,
+                Error = error
+            }));
+        }
+
+        public override Task<GetConfigTextReply> GetConfigText(GetConfigTextRequest request, ServerCallContext context)
+        {
+            var text = _runner.GetConfigText();
+            return Task.FromResult(new GetConfigTextReply()
+            {
+                ConfigYml = text,
+            });
+        }
+    }
+}

src/EllieBot.Coordinator/Shared/Config.cs

@@ -0,0 +1,21 @@
+namespace EllieBot.Coordinator
+{
+    public readonly struct Config
+    {
+        public int TotalShards { get; init; }
+        public int RecheckIntervalMs { get; init; }
+        public string ShardStartCommand { get; init; }
+        public string ShardStartArgs { get; init; }
+        public double UnresponsiveSec { get; init; }
+
+        public Config(int totalShards, int recheckIntervalMs, string shardStartCommand, string shardStartArgs, double unresponsiveSec)
+        {
+            TotalShards = totalShards;
+            RecheckIntervalMs = recheckIntervalMs;
+            ShardStartCommand = shardStartCommand;
+            ShardStartArgs = shardStartArgs;
+            UnresponsiveSec = unresponsiveSec;
+        }
+
+    }
+}

src/EllieBot.Coordinator/Shared/CoordState.cs

@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+
+namespace EllieBot.Coordinator
+{
+    public class CoordState
+    {
+        public List<JsonStatusObject> StatusObjects { get; init; }
+    }
+}

src/EllieBot.Coordinator/Shared/JsonStatusObject.cs

@@ -0,0 +1,9 @@
+namespace EllieBot.Coordinator
+{
+    public class JsonStatusObject
+    {
+        public int? Pid { get; init; }
+        public int GuildCount { get; init; }
+        public ConnState ConnectionState { get; init; }
+    }
+}

src/EllieBot.Coordinator/Shared/ShardStatus.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Diagnostics;
+
+namespace EllieBot.Coordinator
+{
+    public sealed record ShardStatus(
+        int ShardId,
+        DateTime LastUpdate,
+        int GuildCount = 0,
+        ConnState State = ConnState.Disconnected,
+        bool ShouldRestart = false,
+        Process Process = null,
+        int StateCounter = 0
+    );
+}

src/EllieBot.Coordinator/appsettings.Development.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft": "Warning",
+      "Microsoft.Hosting.Lifetime": "Information"
+    }
+  }
+}

src/EllieBot.Coordinator/appsettings.json

@@ -0,0 +1,20 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft": "Warning",
+      "Microsoft.Hosting.Lifetime": "Information"
+    }
+  },
+  "AllowedHosts": "*",
+  "Kestrel": {
+    "EndpointDefaults": {
+      "Protocols": "Http2"
+    },
+    "Endpoints": {
+      "Http": {
+        "Url": "http://localhost:3442"
+      }
+    }
+  }
+}

src/EllieBot.Coordinator/coord.yml

@@ -0,0 +1,12 @@
+# total number of shards
+TotalShards: 3
+# How often do shards ping their state back to the coordinator
+RecheckIntervalMs: 5000
+# Command to run the shard
+ShardStartCommand: dotnet
+# Arguments to run the shard
+# {0} = shard id
+# {1} = total number of shards
+ShardStartArgs: run -p "..\EllieBot\EllieBot.csproj" --no-build -- {0} {1}
+# How long does it take for the shard to be forcefully restarted once it stops reporting its state
+UnresponsiveSec: 30