MySQL Pomelo Entity Framework Core Client integration reference

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To get started with the Aspire MySQL Pomelo Entity Framework Core (EF Core) integrations, follow the Get started with MySQL Pomelo Entity Framework Core integrations guide.

This article includes full details about the Aspire MySQL Pomelo EF Core Client integration, which allows you to connect to and interact with MySQL databases from your Aspire consuming projects using .NET classes to represent and manipulate data.

Installation

You need a MySQL server and connection information for accessing the server. To get started with the Aspire MySQL database integration, install the 📦 Aspire.Pomelo.EntityFrameworkCore.MySql NuGet package in the client-consuming project, that is, the project for the application that uses the MySQL EF Core client. The MySQL client integration registers a DbContext instance that you can use to interact with the MySQL server.

dotnet add package Aspire.Pomelo.EntityFrameworkCore.MySql

#:package Aspire.Pomelo.EntityFrameworkCore.MySql@*

<PackageReference Include="Aspire.Pomelo.EntityFrameworkCore.MySql" Version="*" />

Add MySQL database context

In the Program.cs file of your client-consuming project, call the AddMySqlDbContext extension method on any IHostApplicationBuilder to register a DbContext for use via the dependency injection container. The method takes a connection name parameter.

builder.AddMySqlDbContext<MyDbContext>(connectionName: "mysqldb");

You can then retrieve the MyDbContext instance using dependency injection. For example, to retrieve the data source from an example service:

public class ExampleService(MyDbContext context)
{
    // Use the MySQL database context...
}

For more information on dependency injection, see .NET dependency injection.

Enrich MySQL database context

You may prefer to use the standard Entity Framework method to obtain a database context and add it to the dependency injection container:

builder.Services.AddDbContext<ExampleDbContext>(options =>
    options.UseMySql(builder.Configuration.GetConnectionString("mysqldb")
        ?? throw new InvalidOperationException("Connection string 'mysqldb' not found."), ServerVersion.AutoDetect(builder.Configuration.GetConnectionString("mysqldb"))));

You have more flexibility when you create the database context in this way, for example:

You can reuse existing configuration code for the database context without rewriting it for Aspire.
You can use Entity Framework Core interceptors to modify database operations.
You can choose not to use Entity Framework Core context pooling, which may perform better in some circumstances.

If you use this method, you can enhance the database context with Aspire-style retries, health checks, logging, and telemetry features by calling the EnrichMySqlDatabaseDbContext method:

builder.EnrichMySqlDbContext<ExampleDbContext>(
    configureSettings: settings =>
    {
        settings.DisableRetry = false;
        settings.CommandTimeout = 30 // seconds
    });

The settings parameter is an instance of the MySqlEntityFrameworkCoreSettings class.

Properties of the MySQL resources

When you use the WithReference method to pass a MySQL server or database resource from the AppHost project to a consuming client project, several properties are available to use in the consuming project.

Aspire exposes each property as an environment variable named [RESOURCE]_[PROPERTY]. For instance, the ConnectionString property of a resource called mysqldb becomes MYSQLDB_CONNECTIONSTRING.

MySQL server

The MySQL server resource exposes the following connection properties:

Property Name	Description
`Host`	The hostname or IP address of the MySQL server
`Port`	The port number the MySQL server is listening on
`Username`	The username for authentication (typically `root`)
`Password`	The password for authentication

Example connection properties:

Host: localhost
Port: 3306
Username: root
Password: <generated-password>

MySQL database

The MySQL database resource inherits all properties from its parent MySqlServerResource and adds:

Property Name	Description
`DatabaseName`	The MySQL database name
`ConnectionString`	The full connection string in the format `Server={Host};Port={Port};User ID={Username};Password={Password};Database={DatabaseName}`

Example connection string:

Server=localhost;Port=3306;User ID=root;Password=<generated-password>;Database=mysqldb

Configuration

The Aspire MySQL Pomelo EF Core integration 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 builder.AddMySqlDbContext():

builder.AddMySqlDbContext<ExampleDbContext>(connectionName: "mysqldb");

The connection string is retrieved from the ConnectionStrings configuration section:

{
  "ConnectionStrings": {
    "mysql": "Server=mysql;Database=mysqldb"
  }
}

For more information on how to format this connection string, see MySqlConnector: ConnectionString documentation.

Use configuration providers

The Aspire MySQL database integration supports Microsoft.Extensions.Configuration from configuration files such as appsettings.json by using the Aspire:MySqlConnector key. If you have set up your configurations in the Aspire:MySqlConnector section you can just call the method without passing any parameter.

The following is an example of an appsettings.json that configures some of the available options:

{
  "Aspire": {
    "Pomelo": {
      "EntityFrameworkCore": {
        "MySql": {
          "DisableHealthChecks": true,
          "DisableTracing": true
          }
        }
      }
    }
  }
}

Use inline delegates

You can also pass the Action<MySqlEntityFrameworkCoreSettings> delegate to set up some or all the options inline, for example to disable health checks from code:

builder.AddMySqlDbContext<ExampleDbContext>(
    "mysqldb",
    static settings => settings.DisableHealthChecks = true);

Configuration options

Here are the configurable options with corresponding default values:

Name	Description
`ConnectionString`	The connection string of the MySQL database to connect to
`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

Client integration health checks

By default, Aspire integrations enable health checks for all services. For more information, see Aspire integrations overview.

By default, the Aspire MySQL EF Core integration handles the following:

Adds the health check when MySqlEntityFrameworkCoreSettings.DisableHealthChecks is false, which verifies that a connection can be made and commands can be run against the MySQL database.
Integrates with the /health HTTP endpoint, which specifies all registered health checks must pass for app to be considered ready to accept traffic.

Observability and telemetry

Aspire integrations automatically set up Logging, Tracing, and Metrics configurations, which are sometimes known as the pillars of observability. Depending on the backing service, some integrations may only support some of these features. For example, some integrations support logging and tracing, but not metrics. Telemetry features can also be disabled using the techniques presented in the Configuration section.

Logging

The Aspire MySQL client integration 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.Migrations
Microsoft.EntityFrameworkCore.Model
Microsoft.EntityFrameworkCore.Model.Validation
Microsoft.EntityFrameworkCore.Query
Microsoft.EntityFrameworkCore.Update

Tracing

The Aspire MySQL client integration emits the following tracing activities using OpenTelemetry:

MySqlConnector

Metrics

The Aspire MySQL EF Core integration emits the following metrics using OpenTelemetry:

OpenTelemetry.Instrumentation.EntityFrameworkCore