.NET Aspire Microsoft Entity Framework Core Cosmos DB integration
In this article, you learn how to use the .NET Aspire Microsoft Entity Framework Core Cosmos DB integration. The Aspire.Microsoft.EntityFrameworkCore.Cosmos library is used to register a System.Data.Entity.DbContext as a singleton in the DI container for connecting to Azure Cosmos DB. It also enables corresponding health checks, logging and telemetry.
Get started
To get started with the .NET Aspire Microsoft Entity Framework Core Cosmos DB integration, install the Aspire.Microsoft.EntityFrameworkCore.Cosmos NuGet package in the client-consuming project, i.e., the project for the application that uses the Microsoft Entity Framework Core Cosmos DB client.
dotnet add package Aspire.Microsoft.EntityFrameworkCore.Cosmos
For more information, see dotnet add package or Manage package dependencies in .NET applications.
Example usage
In the Program.cs file of your client-consuming project, call the AddCosmosDbContext extension to register a System.Data.Entity.DbContext for use via the dependency injection container.
builder.AddCosmosDbContext<MyDbContext>("cosmosdb");
You can then retrieve the DbContext instance using dependency injection. For example, to retrieve the client from a service:
public class ExampleService(MyDbContext context)
{
// Use context...
}
For more information on using Entity Framework Core with Azure Cosmos DB, see the Examples for Azure Cosmos DB for NoSQL SDK for .NET.
App host usage
To add Azure Cosmos DB hosting support to your IDistributedApplicationBuilder, install the Aspire.Hosting.Azure.CosmosDB NuGet package in the app host project.
dotnet add package Aspire.Hosting.Azure.CosmosDB
In your app host project, register the .NET Aspire Microsoft Entity Framework Core Cosmos DB integration and consume the service using the following methods:
var builder = DistributedApplication.CreateBuilder(args);
var cosmos = builder.AddAzureCosmosDB("cosmos");
var cosmosdb = cosmos.AddDatabase("cosmosdb");
var exampleProject = builder.AddProject<Projects.ExampleProject>()
.WithReference(cosmosdb);
Tip
To use the Azure Cosmos DB emulator, chain a call to the AddAzureCosmosDB method.
cosmosdb.RunAsEmulator();
Configuration
The .NET Aspire Microsoft Entity Framework Core Cosmos DB integration provides multiple options to configure the Azure Cosmos DB connection based on the requirements and conventions of your project.
Use a connection string
When using a connection string from the ConnectionStrings configuration section, you can provide the name of the connection string when calling builder.AddCosmosDbContext:
builder.AddCosmosDbContext<MyDbContext>("CosmosConnection");
And then the connection string will be retrieved from the ConnectionStrings configuration section:
{
"ConnectionStrings": {
"CosmosConnection": "AccountEndpoint=https://{account_name}.documents.azure.com:443/;AccountKey={account_key};"
}
}
For more information, see the ConnectionString documentation.
Use configuration providers
The .NET Aspire Microsoft Entity Framework Core Cosmos DB integration supports Microsoft.Extensions.Configuration. It loads the EntityFrameworkCoreCosmosSettings from appsettings.json or other configuration files using Aspire:Microsoft:EntityFrameworkCore:Cosmos key. Example appsettings.json that configures some of the options:
{
"Aspire": {
"Microsoft": {
"EntityFrameworkCore": {
"Cosmos": {
"DisableTracing": true
}
}
}
}
}
Use inline delegates
You can also pass the Action<EntityFrameworkCoreCosmosSettings> configureSettings delegate to set up some or all the EntityFrameworkCoreCosmosSettings options inline, for example to disable tracing from code:
builder.AddCosmosDbContext<MyDbContext>(
"cosmosdb",
settings => settings.DisableTracing = true);
Health checks
By default, .NET Aspire integrations enable health checks for all services. For more information, see .NET Aspire integrations overview.
The .NET Aspire Microsoft Entity Framework Core Cosmos DB integration currently doesn't implement health checks, though this may change in future releases.
Observability and telemetry
.NET Aspire integrations automatically set up Logging, Tracing, and Metrics configurations, which are sometimes known as the pillars of observability. For more information about integration observability and telemetry, see .NET Aspire integrations overview. 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 .NET Aspire Microsoft Entity Framework Core Cosmos DB integration uses the following log categories:
- Azure-Cosmos-Operation-Request-Diagnostics
- Microsoft.EntityFrameworkCore.ChangeTracking
- Microsoft.EntityFrameworkCore.Database.Command
- Microsoft.EntityFrameworkCore.Infrastructure
- Microsoft.EntityFrameworkCore.Query
Tracing
The .NET Aspire Microsoft Entity Framework Core Cosmos DB integration will emit the following tracing activities using OpenTelemetry:
- Azure.Cosmos.Operation
- OpenTelemetry.Instrumentation.EntityFrameworkCore
Metrics
The .NET Aspire Microsoft Entity Framework Core Cosmos DB integration currently supports the following metrics:
- 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
