feat(api): Add resilience policies using Polly

This commit adds resilience policies to the API.

In `PollyContextExtensions.cs`, a static class `PollyContextExtensions` is added, which defines item names for context items. It also includes a method `TryGetLogger` that retrieves the logger from the resilience context.

In `ResiliencePipelineDependencyInjectionExtensions.cs`, two static classes are added: `ResiliencePipelines` and `ResiliencePipelineDependencyInjectionExtensions`. The former defines keys/names of different resilience pipelines, while the latter provides extension methods for adding resilience policies to the dependency injection container using Polly. This file includes an example of adding a specific resilience pipeline called "player-clans-update" with fallback, circuit breaker, and retry policies.

Additionally, in the existing file `PlayerService.cs`, changes are made to use the newly added resilience pipeline. The constructor now takes an instance of `ILogger<PlayerService>` and a `ResiliencePipelineProvider<string>`. The logger is used to set the logger property in the resilience context, and then this context is passed to `_resiliencePipeline.ExecuteAsync()` method when updating player clan status.

Lastly, in the existing file `Startup.cs`, a call to add resilience policies using the extension method `AddResiliencePolicies()` is added within the ConfigureServices method.

These changes enhance the API's ability to handle failures and improve its overall resiliency.

WowsKarma.Api/Infrastructure/Resilience/PollyContextExtensions.cs

@@ -0,0 +1,25 @@
+using System.Diagnostics.CodeAnalysis;
+using Polly;
+
+namespace WowsKarma.Api.Infrastructure.Resilience;
+
+public static class PollyContextExtensions
+{
+    /// <summary>
+    /// Defines the item names for context items.
+    /// </summary>
+    /// <seealso cref="ResilienceContext"/>
+    public static class ContextItems
+    {
+        public static readonly ResiliencePropertyKey<ILogger> Logger = new("logger");
+    }
+
+    /// <summary>
+    /// Gets the logger from the resilience context.
+    /// </summary>
+    /// <param name="context">The resilience context.</param>
+    /// <param name="logger">The logger, if initially provided to the context and found.</param>
+    /// <returns></returns>
+    public static bool TryGetLogger(this ResilienceContext context, [NotNullWhen(true)] out ILogger? logger) 
+        => context.Properties.TryGetValue(ContextItems.Logger, out logger);
+}

WowsKarma.Api/Infrastructure/Resilience/ResiliencePipelineDependencyInjectionExtensions.cs

@@ -0,0 +1,91 @@
+using System.Text.Json;
+using Polly;
+using Polly.CircuitBreaker;
+using Polly.Retry;
+using static WowsKarma.Api.Infrastructure.Resilience.PollyContextExtensions;
+
+namespace WowsKarma.Api.Infrastructure.Resilience;
+
+/// <summary>
+/// Keys/Names of the different resilience pipelines.
+/// </summary>
+public static class ResiliencePipelines
+{
+    public const string PlayerClansUpdatePolicyName = "player-clans-update";
+}
+
+/// <summary>
+/// Extension methods for adding resilience policies to the dependency injection container, using Polly.
+/// </summary>
+public static class ResiliencePipelineDependencyInjectionExtensions
+{
+    /// <summary>
+    /// Adds resilience policies to the dependency injection container, using Polly.
+    /// </summary>
+    /// <param name="services">The <see cref="IServiceCollection"/> to add the policies to.</param>
+    /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
+    public static IServiceCollection AddResiliencePolicies(this IServiceCollection services)
+    {
+        services.AddResiliencePipeline<string, bool>(ResiliencePipelines.PlayerClansUpdatePolicyName, builder => builder
+            .AddFallback(new()
+            {
+                ShouldHandle = static args => ValueTask.FromResult(args.Outcome.Exception is not null),
+                
+                FallbackAction = static args =>
+                {
+                    if (args.Outcome.Exception is not BrokenCircuitException or IsolatedCircuitException)
+                    {
+                        (args.Context.TryGetLogger(out ILogger? logger) ? logger : null)?
+                            .LogWarning(args.Outcome.Exception, "Fallback triggered for {Policy} policy", ResiliencePipelines.PlayerClansUpdatePolicyName);
+                    }
+                    
+                    return Outcome.FromResultAsValueTask(false);
+                }
+            })
+            .AddCircuitBreaker(new()
+            {
+                ShouldHandle = static args => ValueTask.FromResult(args.Outcome switch
+                {
+                    { Exception: JsonException } => true,
+                    _ => false
+                }),
+                
+                OnClosed = static args =>
+                {
+                    (args.Context.TryGetLogger(out ILogger? logger) ? logger : null)?
+                        .LogInformation("Circuit closed for {Policy} policy", ResiliencePipelines.PlayerClansUpdatePolicyName);
+                    
+                    return ValueTask.CompletedTask;
+                },
+                
+                OnHalfOpened = static args =>
+                {
+                    (args.Context.TryGetLogger(out ILogger? logger) ? logger : null)?
+                        .LogInformation("Circuit half-opened for {Policy} policy", ResiliencePipelines.PlayerClansUpdatePolicyName);
+                    
+                    return ValueTask.CompletedTask;
+                },
+                
+                OnOpened = static args =>
+                {
+                    (args.Context.TryGetLogger(out ILogger? logger) ? logger : null)?
+                        .LogWarning("Circuit opened for {Policy} policy", ResiliencePipelines.PlayerClansUpdatePolicyName);
+                    
+                    return ValueTask.CompletedTask;
+                }
+            })
+            .AddRetry(new()
+            {
+                BackoffType = DelayBackoffType.Exponential, 
+                MaxRetryAttempts = 4,
+                ShouldHandle = static args => ValueTask.FromResult(args.Outcome switch
+                {
+                    { Exception: HttpRequestException } => true,
+                    _ => false
+                })
+            })
+        );
+
+        return services;
+    }
+}

WowsKarma.Api/Services/PlayerService.cs

@@ -3,8 +3,11 @@
 using Hangfire.Tags.Attributes;
 using Nodsoft.Wargaming.Api.Client.Clients.Wows;
 using Nodsoft.Wargaming.Api.Common.Data.Responses.Wows.Vortex;
+using Polly;
+using Polly.Registry;
 using WowsKarma.Api.Data;
 using WowsKarma.Api.Infrastructure.Exceptions;
+using WowsKarma.Api.Infrastructure.Resilience;
 using WowsKarma.Api.Utilities;
 
 namespace WowsKarma.Api.Services;
@@ -18,14 +21,24 @@ public class PlayerService
 	private readonly WowsPublicApiClient _wgApi;
 	private readonly WowsVortexApiClient _vortex;
 	private readonly ClanService _clanService;
-
-
-	public PlayerService(ApiDbContext context, WowsPublicApiClient wgApi, WowsVortexApiClient vortex, ClanService clanService)
-	{
+	private readonly ILogger<PlayerService> _logger;
+	private readonly ResiliencePipeline<bool> _resiliencePipeline;
+
+
+	public PlayerService(
+		ApiDbContext context, 
+		WowsPublicApiClient wgApi, 
+		WowsVortexApiClient vortex, 
+		ClanService clanService,
+		ILogger<PlayerService> logger,
+		ResiliencePipelineProvider<string> resiliencePipelineRegistry
+	) {
 		_context = context;
 		_wgApi = wgApi;
 		_vortex = vortex;
-		_clanService = clanService;
+		_clanService = clanService;	
+		_logger = logger;
+		_resiliencePipeline = resiliencePipelineRegistry.GetPipeline<bool>(ResiliencePipelines.PlayerClansUpdatePolicyName);
 	}
 
 	/// <summary>
@@ -95,8 +108,22 @@ public async Task<Player> GetPlayerAsync(uint accountId, bool includeRelated = f
 
 		if (includeClanInfo)
 		{
-			player = await UpdatePlayerClanStatusAsync(player, ct);
-			updated = true;
+			ResilienceContext resilienceCtx = ResilienceContextPool.Shared.Get(ct);
+			resilienceCtx.Properties.Set(PollyContextExtensions.ContextItems.Logger, _logger);
+
+			try
+			{
+				// ReSharper disable once HeapView.CanAvoidClosure
+				updated |= await _resiliencePipeline.ExecuteAsync(async ctx =>
+				{
+					player = await UpdatePlayerClanStatusAsync(player, ctx.CancellationToken);
+					return true;
+				}, resilienceCtx);
+			}
+			finally
+			{
+				ResilienceContextPool.Shared.Return(resilienceCtx);
+			}
 		}
 
 		if (updated)

WowsKarma.Api/Startup.cs

@@ -25,6 +25,7 @@
 using WowsKarma.Api.Data;
 using WowsKarma.Api.Hubs;
 using WowsKarma.Api.Infrastructure.Authorization;
+using WowsKarma.Api.Infrastructure.Resilience;
 using WowsKarma.Api.Infrastructure.Telemetry;
 using WowsKarma.Api.Middlewares;
 using WowsKarma.Api.Minimap.Client;
@@ -269,9 +270,10 @@ public void ConfigureServices(IServiceCollection services)
 
 		services.AddResponseCompression(opts =>
 		{
-			opts.MimeTypes = ResponseCompressionDefaults.MimeTypes.Concat(
-				new[] { "application/octet-stream" });
+			opts.MimeTypes = ResponseCompressionDefaults.MimeTypes.Concat(["application/octet-stream"]);
 		});
+
+		services.AddResiliencePolicies();
 	}
 
 	// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

WowsKarma.Api/WowsKarma.Api.csproj

@@ -54,6 +54,7 @@
     <PackageReference Include="Nodsoft.Wargaming.Api.Client" Version="0.3.5" />
     <PackageReference Include="Nodsoft.WowsReplaysUnpack.ExtendedData" Version="2.0.1" />
     <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="8.0.0" />
+    <PackageReference Include="Polly.Extensions" Version="8.2.1" />
     <PackageReference Include="Serilog.AspNetCore" Version="8.0.1" />
     <PackageReference Include="Serilog.Extensions.Logging" Version="8.0.0" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />