CosmosDB

This connector simplifies accessing Azure CosmosDB databases. It supports the following .NET drivers:

• Microsoft.Azure.Cosmos, which provides a CosmosClient.

The remainder of this page assumes you're familiar with the basic concepts of Steeltoe Connectors.

Usage

To use this connector:

1. Create a CosmosDB server instance or use the emulator.
2. Add NuGet references to your project.
3. Configure your connection string in appsettings.json.
4. Initialize the Steeltoe Connector at startup.
5. Use the driver-specific connection/client instance.

Add NuGet References

To use this connector, add a NuGet reference to Steeltoe.Connectors.

Also add a NuGet reference to one of the .NET drivers listed above, as you would if you were not using Steeltoe.

Configure connection string

The CosmosDB connection string can be obtained as described here.

The following example appsettings.json uses the emulator:

{
  "Steeltoe": {
    "Client": {
      "CosmosDb": {
        "Default": {
          "ConnectionString": "AccountEndpoint=https://localhost:8081;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==",
          "Database": "TestDatabase"
        }
      }
    }
  }
}

Notice this configuration file contains the database name, in addition to the connection string. This value is exposed as CosmosDbOptions.Database.

Initialize Steeltoe Connector

Update your Program.cs as below to initialize the Connector:

using Steeltoe.Connectors.CosmosDb;

var builder = WebApplication.CreateBuilder(args);
builder.AddCosmosDb();

Use CosmosClient

Start by defining a class that contains container data:

using Newtonsoft.Json;

public class SampleObject
{
    [JsonProperty(PropertyName = "id")]
    public string Id { get; set; }

    public string? Text { get; set; }
}

To obtain a CosmosClient instance in your application, inject the Steeltoe factory in a controller or view:

using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.Cosmos;
using Microsoft.Azure.Cosmos.Linq;
using Steeltoe.Connectors;
using Steeltoe.Connectors.CosmosDb;

public class HomeController : Controller
{
    public async Task<IActionResult> Index(
        [FromServices] ConnectorFactory<CosmosDbOptions, CosmosClient> connectorFactory)
    {
        var connector = connectorFactory.Get();
        CosmosClient client = connector.GetConnection();

        Container container = client.GetContainer(connector.Options.Database, "TestContainer");
        List<SampleObject> sampleObjects = new();

        await foreach (SampleObject sampleObject in GetAllAsync(container))
        {
            sampleObjects.Add(sampleObject);
        }

        return View(sampleObjects);
    }

    private async IAsyncEnumerable<SampleObject> GetAllAsync(Container container)
    {
        using FeedIterator<SampleObject> iterator =
            container.GetItemLinqQueryable<SampleObject>().ToFeedIterator();

        while (iterator.HasMoreResults)
        {
            FeedResponse<SampleObject> response = await iterator.ReadNextAsync();

            foreach (SampleObject sampleObject in response)
            {
                yield return sampleObject;
            }
        }
    }
}

A complete sample app that uses CosmosClient is provided at https://github.com/SteeltoeOSS/Samples/tree/main/Connectors/src/CosmosDb.

Cloud Foundry

This Connector supports the following service brokers:

• VMware Tanzu Cloud Service Broker for Azure

You can create and bind an instance to your application by using the Cloud Foundry CLI:

# Create CosmosDB service
cf create-service csb-azure-cosmosdb-sql mini myCosmosDbService

# Bind service to your app
cf bind-service myApp myCosmosDbService

# Restage the app to pick up change
cf restage myApp