Wire NpgsqlDataSource pool into DI for PostgreSQL provider (#10)

* Initial plan

* Add NpgsqlDataSource pool wiring to DI (Issue 1.4)"

- PostgreSqlDatabaseProvider: accept NpgsqlDataSource via constructor injection, use it in Initialise()
- PostgreSqlDesignTimeJellyfinDbFactory: build NpgsqlDataSource from connection string for design-time use
- ServiceCollectionExtensions: register NpgsqlDataSource as singleton with pool params (MinPoolSize=2, MaxPoolSize=20, CommandTimeout=30) from CustomProviderOptions.Options

Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com>

src/Jellyfin.Database/Jellyfin.Database.Providers.PostgreSQL/PostgreSqlDatabaseProvider.cs

@@ -1,11 +1,11 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Jellyfin.Database.Implementations;
 using Jellyfin.Database.Implementations.DbConfiguration;
 using Microsoft.EntityFrameworkCore;
+using Npgsql;
 
 namespace Jellyfin.Database.Providers.PostgreSQL;
 
@@ -18,24 +18,25 @@ public sealed class PostgreSqlDatabaseProvider : IJellyfinDatabaseProvider
     private const string BackupNotSupportedMessage =
         "Automated migration backups are not supported for PostgreSQL. Use the jellyfin-pg-backup CronJob for nightly S3 backups.";
 
+    private readonly NpgsqlDataSource _dataSource;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PostgreSqlDatabaseProvider"/> class.
+    /// </summary>
+    /// <param name="dataSource">The <see cref="NpgsqlDataSource"/> used for PostgreSQL connections.</param>
+    public PostgreSqlDatabaseProvider(NpgsqlDataSource dataSource)
+    {
+        _dataSource = dataSource;
+    }
+
     /// <inheritdoc/>
     public IDbContextFactory<JellyfinDbContext>? DbContextFactory { get; set; }
 
     /// <inheritdoc/>
     public void Initialise(DbContextOptionsBuilder options, DatabaseConfigurationOptions databaseConfiguration)
     {
-        var connectionString =
-            Environment.GetEnvironmentVariable("POSTGRES_CONNECTION_STRING")
-            ?? databaseConfiguration.CustomProviderOptions?.Options
-                ?.FirstOrDefault(o => o.Key.Equals("ConnectionString", StringComparison.OrdinalIgnoreCase))
-                ?.Value
-            ?? databaseConfiguration.CustomProviderOptions?.ConnectionString
-            ?? throw new InvalidOperationException(
-                "No PostgreSQL connection string found. Set the POSTGRES_CONNECTION_STRING environment variable, " +
-                "or provide it via CustomProviderOptions.Options[\"ConnectionString\"] or CustomProviderOptions.ConnectionString.");
-
         options.UseNpgsql(
-            connectionString,
+            _dataSource,
             o => o.MigrationsAssembly(GetType().Assembly.FullName));
     }
 

src/Jellyfin.Database/Jellyfin.Database.Providers.PostgreSQL/PostgreSqlDesignTimeJellyfinDbFactory.cs

@@ -4,6 +4,7 @@ using Jellyfin.Database.Implementations.Locking;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Design;
 using Microsoft.Extensions.Logging.Abstractions;
+using Npgsql;
 
 namespace Jellyfin.Database.Providers.PostgreSQL;
 
@@ -21,12 +22,21 @@ internal sealed class PostgreSqlDesignTimeJellyfinDbFactory : IDesignTimeDbConte
             ?? "Host=localhost;Database=jellyfin;Username=postgres;Password=postgres";
 
         var optionsBuilder = new DbContextOptionsBuilder<JellyfinDbContext>();
-        optionsBuilder.UseNpgsql(connectionString, o => o.MigrationsAssembly(GetType().Assembly));
+
+        // Build a NpgsqlDataSource for EF Core configuration. The DI-owned singleton data source
+        // is not available in design-time context; this instance is intentionally not disposed here
+        // because EF Core holds a reference to it for the lifetime of the returned context.
+        // As a design-time-only factory (used only for dotnet-ef CLI operations), the process
+        // exits after the migration is applied, which releases all resources.
+#pragma warning disable CA2000 // Dispose objects before losing scope
+        var dataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
+#pragma warning restore CA2000 // Dispose objects before losing scope
+        optionsBuilder.UseNpgsql(dataSource, o => o.MigrationsAssembly(GetType().Assembly));
 
         return new JellyfinDbContext(
             optionsBuilder.Options,
             NullLogger<JellyfinDbContext>.Instance,
-            new PostgreSqlDatabaseProvider(),
+            new PostgreSqlDatabaseProvider(dataSource),
             new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
     }
 }