Health check for CHES

Author: areyeslo

source/backend/api/Helpers/Healthchecks/ChesHealthCheck.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Pims.Api.Repositories.Ches;
+
+namespace Pims.Api.Helpers.Healthchecks
+{
+    /// <summary>
+    /// Health check for CHES service connectivity.
+    /// </summary>
+    public class ChesHealthCheck : IHealthCheck
+    {
+        private readonly IEmailRepository _repository;
+
+        public ChesHealthCheck(IEmailRepository repository)
+        {
+            _repository = repository;
+        }
+
+        public async Task<HealthCheckResult> CheckHealthAsync(
+            HealthCheckContext context, CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                const int maxJitterMilliseconds = 10000;
+                var jitter = Random.Shared.Next(0, maxJitterMilliseconds + 1);
+                if (jitter > 0)
+                {
+                    await Task.Delay(TimeSpan.FromMilliseconds(jitter), cancellationToken);
+                }
+
+                var response = await _repository.TryGetHealthAsync();
+                if (response.StatusCode != System.Net.HttpStatusCode.OK)
+                {
+                    return new HealthCheckResult(HealthStatus.Degraded, $"CHES health check returned status code: {response.StatusCode}");
+                }
+            }
+            catch (Exception ex)
+            {
+                return new HealthCheckResult(context.Registration.FailureStatus, $"CHES health check failed with exception: {ex.Message}");
+            }
+            return HealthCheckResult.Healthy();
+        }
+    }
+}

source/backend/api/Repositories/Ches/ChesAuthRepository.cs

@@ -80,9 +80,6 @@ private async Task<ExternalResponse<JwtResponse>> TryRequestToken()
         {
             _logger.LogDebug("Getting authentication token...");
 
-            using HttpClient client = _httpClientFactory.CreateClient("Pims.Api.Logging");
-            client.DefaultRequestHeaders.Accept.Clear();
-
             var requestForm = new Dictionary<string, string>
                 {
                     { "grant_type", "client_credentials" },

source/backend/api/Repositories/Ches/ChesRepository.cs

@@ -107,5 +107,18 @@ public async Task<ExternalResponse<EmailResponse>> SendEmailAsync(EmailRequest r
             _logger.LogDebug($"Finished sending email");
             return result;
         }
+
+        public async Task<HttpResponseMessage> TryGetHealthAsync()
+        {
+            _logger.LogDebug("Checking health of CHES service");
+            string authenticationToken = await _authRepository.GetTokenAsync();
+
+            Uri endpoint = new(this._config.ChesHost, "/api/v1/health");
+
+            Task<HttpResponseMessage> result = GetRawAsync(endpoint, authenticationToken);
+
+            _logger.LogDebug($"Finished checking health of CHES service");
+            return await result;
+        }
     }
 }

source/backend/api/Repositories/Ches/IEmailRepository.cs

@@ -1,3 +1,4 @@
+using System.Net.Http;
 using System.Threading.Tasks;
 using Pims.Api.Models.Ches;
 using Pims.Api.Models.Requests.Http;
@@ -7,5 +8,7 @@ namespace Pims.Api.Repositories.Ches
     public interface IEmailRepository
     {
         Task<ExternalResponse<EmailResponse>> SendEmailAsync(EmailRequest request);
+
+        Task<HttpResponseMessage> TryGetHealthAsync();
     }
 }

source/backend/api/Startup.cs

@@ -373,6 +373,16 @@ public void ConfigureServices(IServiceCollection services)
                 { Period = TimeSpan.FromMinutes(allHealthCheckOptions.Cdogs.Period) });
             }
 
+            if (allHealthCheckOptions.Ches.Enabled)
+            {
+                services.AddHealthChecks().Add(new HealthCheckRegistration(
+                    "Ches",
+                    sp => new ChesHealthCheck(sp.GetService<IEmailRepository>()),
+                    null,
+                    new string[] { SERVICES, EXTERNAL, SYSTEMCHECK })
+                { Period = TimeSpan.FromMinutes(allHealthCheckOptions.Ches.Period) });
+            }
+
             services.AddApiVersioning(options =>
             {
                 options.ReportApiVersions = true;
@@ -574,7 +584,7 @@ private static void AddPimsApiServices(IServiceCollection services)
             services.AddScoped<IManagementActivityService, ManagementActivityService>();
             services.AddScoped<IManagementFileStatusSolver, ManagementFileStatusSolver>();
             services.AddScoped<IFilePropertyLocationUpdateSolver, FilePropertyLocationUpdateSolver>();
-            services.AddScoped<IChesService, ChesService>();
+            services.AddScoped<IEmailService, ChesService>();
         }
 
         /// <summary>

source/backend/api/appsettings.Development.json

@@ -16,6 +16,10 @@
     "Ltsa": {
       "Enabled": false,
       "Period": 60
+    },
+    "Ches": {
+      "Enabled": false,
+      "Period": 60
     }
   },
   "Serilog": {

source/backend/api/appsettings.Local.json

@@ -26,6 +26,10 @@
     "Mayan": {
       "Period": 60,
       "Enabled": false
+    },
+    "Ches": {
+      "Period": 60,
+      "Enabled": false
     }
   },
   "Logging": {

source/backend/api/appsettings.Test.json

@@ -16,6 +16,10 @@
     "Ltsa": {
       "Enabled": false,
       "Period": 15
+    },
+    "Ches": {
+      "Enabled": false,
+      "Period": 15
     }
   },
   "Serilog": {

source/backend/api/appsettings.Uat.json

@@ -16,6 +16,10 @@
     "Ltsa": {
       "Enabled": false,
       "Period": 5
+    },
+    "Ches": {
+      "Enabled": false,
+      "Period": 5
     }
   },
   "Serilog": {

source/backend/api/appsettings.json

@@ -41,6 +41,10 @@
     "Cdogs": {
       "Enabled": true,
       "Period": 1
+    },
+    "Ches": {
+      "Enabled": true,
+      "Period": 1
     }
   },
   "Swagger": {
@@ -153,6 +157,12 @@
     "ServiceClientId": "[CLIENT_ID]",
     "ServiceClientSecret": "[CLIENT_SECRET]"
   },
+  "Ches": {
+    "AuthEndpoint": "[AUTH_ENDPOINT]",
+    "ChesHost": "[CDOGS_HOST]",
+    "ServiceClientId": "[CLIENT_ID]",
+    "ServiceClientSecret": "[CLIENT_SECRET]"
+  },
   "Polly": {
     "MaxRetries": 3,
     "DelayInSeconds": 1