Extensibility

Steeltoe Connectors cover a fixed set of supported data stores and messaging systems (PostgreSQL, MySQL, SQL Server, MongoDB, Cosmos DB, RabbitMQ, and Redis/Valkey). They are not open-ended plug-ins; extensibility means shaping platform credentials into the connection strings external drivers for those built-in connectors already understand.

Connectors map credentials from Cloud Foundry service bindings and Service Binding Spec for Kubernetes into configuration keys starting with steeltoe:service-bindings and merge them with local settings from Steeltoe:Client. Each connector runs the binding logic for its own service type.

Note

The remainder of this page covers Cloud Foundry. Equivalent support for custom Kubernetes service bindings is not yet implemented. If you need it, open an issue describing your scenario.

To use a third-party VCAP_SERVICES structure, populate the steeltoe:service-bindings keys yourself. It is recommended to turn off the built-in binding logic to prevent conflicts by setting SkipDefaultServiceBindings to true. Doing so will still merge with local settings from Steeltoe:Client.

Tip

See the Cloud Foundry configuration provider for vcap:* keys and VCAP_SERVICES in general.

For example, to use a third-party Cloud Foundry service broker for PostgreSQL that sets the VCAP_SERVICES environment variable to:

{
  "custom-postgres-broker": [
    {
      "name": "products-db",
      "credentials": {
        "custom-hostname-key": "example.cloud.com",
        "custom-port-key": 2345,
        "custom-username-key": "products-user",
        "custom-password-key": "products-secret",
        "custom-database-name-key": "product-database"
      }
    },
    {
      "name": "orders-db",
      "credentials": {
        "custom-hostname-key": "example.cloud.com",
        "custom-port-key": 2345,
        "custom-username-key": "orders-user",
        "custom-password-key": "orders-secret",
        "custom-database-name-key": "order-database"
      }
    }
  ]
}

The following code can be used to map the PostgreSQL credentials to the format that NpgsqlConnectionStringBuilder expects:

using Npgsql;
using Steeltoe.Configuration.CloudFoundry;
using Steeltoe.Connectors;
using Steeltoe.Connectors.PostgreSql;

var builder = WebApplication.CreateBuilder();
builder.AddCloudFoundryConfiguration();
MapCustomServiceBindings("custom-postgres-broker");
builder.AddPostgreSql(configure => configure.SkipDefaultServiceBindings = true, null);
var app = builder.Build();

var factory = app.Services.GetRequiredService<ConnectorFactory<PostgreSqlOptions, NpgsqlConnection>>();

PostgreSqlOptions productsDbOptions = factory.Get("products-db").Options;
Console.WriteLine(productsDbOptions.ConnectionString);
// Database=product-database;Host=example.cloud.com;Password=products-secret;Port=2345;Username=products-user

PostgreSqlOptions ordersDbOptions = factory.Get("orders-db").Options;
Console.WriteLine(ordersDbOptions.ConnectionString);
// Database=order-database;Host=example.cloud.com;Password=orders-secret;Port=2345;Username=orders-user

void MapCustomServiceBindings(string brokerName)
{
    var options = builder.Configuration.GetSection("vcap").Get<CloudFoundryServicesOptions>();

    foreach (CloudFoundryService service in options?.Services
        .Where(pair => pair.Key == brokerName)
        .SelectMany(pair => pair.Value) ?? [])
    {
        builder.Configuration.AddInMemoryCollection(new Dictionary<string, string?>
        {
            // Map credentials into the property names expected by NpgsqlConnectionStringBuilder.
            [$"steeltoe:service-bindings:postgresql:{service.Name}:host"] = service.Credentials["custom-hostname-key"].Value,
            [$"steeltoe:service-bindings:postgresql:{service.Name}:port"] = service.Credentials["custom-port-key"].Value,
            [$"steeltoe:service-bindings:postgresql:{service.Name}:username"] = service.Credentials["custom-username-key"].Value,
            [$"steeltoe:service-bindings:postgresql:{service.Name}:password"] = service.Credentials["custom-password-key"].Value,
            [$"steeltoe:service-bindings:postgresql:{service.Name}:database"] = service.Credentials["custom-database-name-key"].Value
        });
    }
}

Tip

See Advanced settings to customize the built-in Connectors.