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.NET Aspire PostgreSQL Entity Framework Core component
This article describes the .NET Aspire PostgreSQL Entity Framework Core component.
how-to
07/17/2024

.NET Aspire PostgreSQL Entity Framework Core component

In this article, you learn how to use the .NET Aspire PostgreSQL Entity Framework Core component. The Aspire.Npgsql.EntityFrameworkCore.PostgreSQL library is used to register a xref:Microsoft.EntityFrameworkCore.DbContext service for connecting to a PostgreSQL database. It also enables corresponding health checks, logging and telemetry.

PostgreSQL is a powerful, open source, object-relational database system. The .NET Aspire PostgreSQL Entity Framework component streamlines essential database context and connection configurations for you by handling the following concerns:

  • Registers EntityFrameworkCore in the DI container for connecting to PostgreSQL database.
  • Automatically configures the following:
    • Connection pooling to efficiently managed HTTP requests and database connections
    • Automatic retries to increase app resiliency
    • Health checks, logging and telemetry to improve app monitoring and diagnostics

Prerequisites

Get started

To get started with the .NET Aspire PostgreSQL Entity Framework Core component, install the Aspire.Npgsql.EntityFrameworkCore.PostgreSQL NuGet package in the consuming client project.

.NET CLI

dotnet add package Aspire.Npgsql.EntityFrameworkCore.PostgreSQL

PackageReference

<PackageReference Include="Aspire.Npgsql.EntityFrameworkCore.PostgreSQL"
                  Version="[SelectVersion]" />

For more information, see dotnet add package or Manage package dependencies in .NET applications.

Example usage

In the :::no-loc text="Program.cs"::: file of your component-consuming project, call the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.AddNpgsqlDbContext%2A extension to register a xref:System.Data.Entity.DbContext for use via the dependency injection container.

builder.AddNpgsqlDbContext<YourDbContext>("postgresdb");

You can then retrieve the YourDbContext instance using dependency injection. For example, to retrieve the client from a service:

public class ExampleService(YourDbContext context)
{
    // Use context...
}

App host usage

[!INCLUDE postgresql-app-host]

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres");
var postgresdb = postgres.AddDatabase("postgresdb");

var myService = builder.AddProject<Projects.MyService>()
                       .WithReference(postgresdb);

[!INCLUDE postgresql-explicit-username-password]

[!INCLUDE postgresql-flexible-server]

Configuration

The .NET Aspire PostgreSQL Entity Framework Core component provides multiple configuration approaches and options to meet the requirements and conventions of your project.

Use a connection string

When using a connection string from the ConnectionStrings configuration section, you provide the name of the connection string when calling AddNpgsqlDbContext:

builder.AddNpgsqlDbContext<MyDbContext>("myConnection");

The connection string is retrieved from the ConnectionStrings configuration section:

{
  "ConnectionStrings": {
    "myConnection": "Host=myserver;Database=test"
  }
}

The EnrichNpgsqlDbContext won't make use of the ConnectionStrings configuration section since it expects a DbContext to be registered at the point it is called.

For more information, see the ConnectionString.

Use configuration providers

The .NET Aspire PostgreSQL Entity Framework Core component supports xref:Microsoft.Extensions.Configuration?displayProperty=fullName. It loads the xref:Aspire.Npgsql.EntityFrameworkCore.PostgreSQL.NpgsqlEntityFrameworkCorePostgreSQLSettings from configuration files such as :::no-loc text="appsettings.json"::: by using the Aspire:Npgsql:EntityFrameworkCore:PostgreSQL key. If you have set up your configurations in the Aspire:Npgsql:EntityFrameworkCore:PostgreSQL section you can just call the method without passing any parameter.

The following example shows an :::no-loc text="appsettings.json"::: file that configures some of the available options:

{
  "Aspire": {
    "Npgsql": {
      "EntityFrameworkCore": {
        "PostgreSQL": {
          "ConnectionString": "YOUR_CONNECTIONSTRING",
          "DbContextPooling": true,
          "DisableHealthChecks": true,
          "DisableTracing": true
        }
      }
    }
  }
}

Use inline delegates

You can also pass the Action<NpgsqlEntityFrameworkCorePostgreSQLSettings> delegate to set up some or all the options inline, for example to set the ConnectionString:

builder.AddNpgsqlDbContext<YourDbContext>(
    "db",
    static settings => settings.ConnectionString = "YOUR_CONNECTIONSTRING");

Configure multiple DbContext classes

If you want to register more than one xref:Microsoft.EntityFrameworkCore.DbContext with different configuration, you can use $"Aspire:Npgsql:EntityFrameworkCore:PostgreSQL:{typeof(TContext).Name}" configuration section name. The json configuration would look like:

{
  "Aspire": {
    "Npgsql": {
      "EntityFrameworkCore": {
        "PostgreSQL": {
          "ConnectionString": "YOUR_CONNECTIONSTRING",
          "DbContextPooling": true,
          "DisableHealthChecks": true,
          "DisableTracing": true,
          "AnotherDbContext": {
            "ConnectionString": "AnotherDbContext_CONNECTIONSTRING",
            "DisableTracing": false
          }
        }
      }
    }
  }
}

Then calling the xref:Microsoft.Extensions.Hosting.AspireEFPostgreSqlExtensions.AddNpgsqlDbContext%2A method with AnotherDbContext type parameter would load the settings from Aspire:Npgsql:EntityFrameworkCore:PostgreSQL:AnotherDbContext section.

builder.AddNpgsqlDbContext<AnotherDbContext>();

Configuration options

Here are the configurable options with corresponding default values:

Name Description
ConnectionString The connection string of the SQL Server database to connect to.
MaxRetryCount The maximum number of retry attempts. Default value is 6, set it to 0 to disable the retry mechanism.
DisableHealthChecks A boolean value that indicates whether the database health check is disabled or not.
DisableTracing A boolean value that indicates whether the OpenTelemetry tracing is disabled or not.
DisableMetrics A boolean value that indicates whether the OpenTelemetry metrics are disabled or not.

[!INCLUDE component-health-checks]

By default, the .NET Aspire PostgreSQL Entity Framework Core components handles the following:

  • Adds the DbContextHealthCheck, which calls EF Core's xref:Microsoft.EntityFrameworkCore.Storage.IDatabaseCreator.CanConnectAsync%2A method. The name of the health check is the name of the TContext type.
  • Integrates with the /health HTTP endpoint, which specifies all registered health checks must pass for app to be considered ready to accept traffic

[!INCLUDE component-observability-and-telemetry]

Logging

The .NET Aspire PostgreSQL Entity Framework Core component uses the following Log categories:

  • Microsoft.EntityFrameworkCore.ChangeTracking
  • Microsoft.EntityFrameworkCore.Database.Command
  • Microsoft.EntityFrameworkCore.Database.Connection
  • Microsoft.EntityFrameworkCore.Database.Transaction
  • Microsoft.EntityFrameworkCore.Infrastructure
  • Microsoft.EntityFrameworkCore.Infrastructure
  • Microsoft.EntityFrameworkCore.Migrations
  • Microsoft.EntityFrameworkCore.Model
  • Microsoft.EntityFrameworkCore.Model.Validation
  • Microsoft.EntityFrameworkCore.Query
  • Microsoft.EntityFrameworkCore.Update

Tracing

The .NET Aspire PostgreSQL Entity Framework Core component will emit the following Tracing activities using OpenTelemetry:

  • "Npgsql"

Metrics

The .NET Aspire PostgreSQL Entity Framework Core component will emit the following metrics using OpenTelemetry:

  • Microsoft.EntityFrameworkCore:

    • ec_Microsoft_EntityFrameworkCore_active_db_contexts
    • ec_Microsoft_EntityFrameworkCore_total_queries
    • ec_Microsoft_EntityFrameworkCore_queries_per_second
    • ec_Microsoft_EntityFrameworkCore_total_save_changes
    • ec_Microsoft_EntityFrameworkCore_save_changes_per_second
    • ec_Microsoft_EntityFrameworkCore_compiled_query_cache_hit_rate
    • ec_Microsoft_Entity_total_execution_strategy_operation_failures
    • ec_Microsoft_E_execution_strategy_operation_failures_per_second
    • ec_Microsoft_EntityFramew_total_optimistic_concurrency_failures
    • ec_Microsoft_EntityF_optimistic_concurrency_failures_per_second

  • Npgsql:

    • ec_Npgsql_bytes_written_per_second
    • ec_Npgsql_bytes_read_per_second
    • ec_Npgsql_commands_per_second
    • ec_Npgsql_total_commands
    • ec_Npgsql_current_commands
    • ec_Npgsql_failed_commands
    • ec_Npgsql_prepared_commands_ratio
    • ec_Npgsql_connection_pools
    • ec_Npgsql_multiplexing_average_commands_per_batch
    • ec_Npgsql_multiplexing_average_write_time_per_batch

See also