CosmosDbConnection.cs

public static class CosmosDbConnection
{
        private const string EndpointUri = "https://localhost:8081";
        private const string PrimaryKey = "yourprimarykey==";
        private static CosmosClient _instance = null;
        private static readonly CosmosClientOptions CosmosClientOptions = new CosmosClientOptions()
        {
            ConnectionMode = ConnectionMode.Direct,
            ApplicationName = "CosmosStarter"            
        };


        public static CosmosClient Instance => _instance ??= new CosmosClient(EndpointUri, PrimaryKey, CosmosClientOptions);
}