Implemented a startup task that will instantiate all the DI so first API isn't having to eat that overhead.

API/Controllers/SettingsController.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
+using API.Data;
 using API.DTOs;
 using API.Entities.Enums;
 using API.Extensions;
@@ -9,6 +10,8 @@ using API.Helpers.Converters;
 using API.Interfaces;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore.Internal;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
 
 namespace API.Controllers
@@ -19,12 +22,14 @@ namespace API.Controllers
         private readonly ILogger<SettingsController> _logger;
         private readonly IUnitOfWork _unitOfWork;
         private readonly ITaskScheduler _taskScheduler;
+        private readonly IConfiguration _configuration;
 
-        public SettingsController(ILogger<SettingsController> logger, IUnitOfWork unitOfWork, ITaskScheduler taskScheduler)
+        public SettingsController(ILogger<SettingsController> logger, IUnitOfWork unitOfWork, ITaskScheduler taskScheduler, IConfiguration configuration)
         {
             _logger = logger;
             _unitOfWork = unitOfWork;
             _taskScheduler = taskScheduler;
+            _configuration = configuration;
         }
 
         [HttpGet("")]
@@ -51,6 +56,9 @@ namespace API.Controllers
 
             // We do not allow CacheDirectory changes, so we will ignore.
             var currentSettings = await _unitOfWork.SettingsRepository.GetSettingsAsync();
+            
+            var logLevelOptions = new LogLevelOptions();
+            _configuration.GetSection("Logging:LogLevel").Bind(logLevelOptions);
 
             foreach (var setting in currentSettings)
             {
@@ -72,8 +80,15 @@ namespace API.Controllers
                     Environment.SetEnvironmentVariable("KAVITA_PORT", setting.Value);
                     _unitOfWork.SettingsRepository.Update(setting);
                 }
+                
+                if (setting.Key == ServerSettingKey.LoggingLevel && updateSettingsDto.LoggingLevel + "" != setting.Value)
+                {
+                    setting.Value = updateSettingsDto.LoggingLevel + "";
+                    _unitOfWork.SettingsRepository.Update(setting);
+                }
             }
-
+            
+            _configuration.GetSection("Logging:LogLevel:Default").Value = updateSettingsDto.LoggingLevel + "";
             if (!_unitOfWork.HasChanges()) return Ok("Nothing was updated");
 
             if (!_unitOfWork.HasChanges() || !await _unitOfWork.Complete())
@@ -90,5 +105,12 @@ namespace API.Controllers
         {
             return Ok(CronConverter.Options);
         }
+        
+        [Authorize(Policy = "RequireAdminRole")]
+        [HttpGet("log-levels")]
+        public ActionResult<IEnumerable<string>> GetLogLevels()
+        {
+            return Ok(new string[] {"Trace", "Debug", "Information", "Warning", "Critical", "None"});
+        }
     }
 }

API/Data/LogLevelOptions.cs

@@ -0,0 +1,9 @@
+namespace API.Data
+{
+    public class LogLevelOptions
+    {
+        public const string Logging = "LogLevel";
+        
+        public string Default { get; set; }
+    }
+}

API/Extensions/ApplicationServiceExtensions.cs

@@ -56,5 +56,9 @@ namespace API.Extensions
 
             return services;
         }
+        
+        public static IServiceCollection AddStartupTask<T>(this IServiceCollection services)
+            where T : class, IStartupTask
+            => services.AddTransient<IStartupTask, T>();
     }
 }

API/Interfaces/Services/IStartupTask.cs

@@ -0,0 +1,10 @@
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace API.Interfaces.Services
+{
+    public interface IStartupTask
+    {
+        Task ExecuteAsync(CancellationToken cancellationToken = default);
+    }
+}

API/Services/TaskScheduler.cs

@@ -39,9 +39,9 @@ namespace API.Services
             _cleanupService = cleanupService;
             _directoryService = directoryService;
 
-
+            //Hangfire.RecurringJob.RemoveIfExists();
             ScheduleTasks();
-            //JobStorage.Current.GetMonitoringApi().
+            //JobStorage.Current.GetMonitoringApi().EnqueuedJobs()
 
         }
 

API/Services/WarmupServiceStartupTask.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using API.Interfaces.Services;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace API.Services
+{
+    public class WarmupServicesStartupTask : IStartupTask
+    {
+        private readonly IServiceCollection _services;
+        private readonly IServiceProvider _provider;
+        public WarmupServicesStartupTask(IServiceCollection services, IServiceProvider provider)
+        {
+            _services = services;
+            _provider = provider;
+        }
+
+        public Task ExecuteAsync(CancellationToken cancellationToken)
+        {
+            using (var scope = _provider.CreateScope())
+            {
+                foreach (var singleton in GetServices(_services))
+                {
+                    scope.ServiceProvider.GetServices(singleton);
+                }
+            }
+
+            return Task.CompletedTask;
+        }
+        
+        static IEnumerable<Type> GetServices(IServiceCollection services)
+        {
+            return services
+                .Where(descriptor => descriptor.ImplementationType != typeof(WarmupServicesStartupTask))
+                .Where(descriptor => !descriptor.ServiceType.ContainsGenericParameters)
+                .Select(descriptor => descriptor.ServiceType)
+                .Distinct();
+        }
+    }
+
+}

API/Startup.cs

@@ -1,8 +1,10 @@
 using System;
 using System.IO.Compression;
 using System.Linq;
+using API.Data;
 using API.Extensions;
 using API.Middleware;
+using API.Services;
 using Hangfire;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
@@ -12,7 +14,9 @@ using Microsoft.AspNetCore.ResponseCompression;
 using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
 using Microsoft.OpenApi.Models;
 
 namespace API
@@ -42,7 +46,6 @@ namespace API
             {
                 c.SwaggerDoc("v1", new OpenApiInfo { Title = "API", Version = "v1" });
             });
-            // This doesn't seem to work.
             services.AddResponseCompression(options =>
             {
                 options.Providers.Add<BrotliCompressionProvider>();
@@ -60,7 +63,9 @@ namespace API
             services.AddResponseCaching();
             
 
-            
+            services
+                .AddStartupTask<WarmupServicesStartupTask>()
+                .TryAddSingleton(services);
             
         }
 
@@ -113,7 +118,6 @@ namespace API
             
                 await next();
             });
-            
 
             app.UseEndpoints(endpoints =>
             {