Debugging Azure Functions with local Cosmos DB Emulator - azure

Question

I am attempting to test an Azure Function (written in C# on VS 2019 Community, triggered with an HTTP trigger) running against a local Cosmos DB Emulator. When my code attempts to communicate with the emulator, it appears to time out, and gives me an exception.
The relevant code snippet:
CosmosClient client = new CosmosClient(storageURL, authKeyString);
try
{
Database oldDB = client.GetDatabase(dbName);
DatabaseResponse dbResp = await oldDB.DeleteAsync();
}
My input variables:
storageURL "http://localhost:8081"
authKeyString "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw=="
On the call to GetDatabase(), the code waits for a good long while and throws an exception:
{"The operation was canceled."}
CancellationToken: IsCancellationRequested = true
Data: {System.Collections.ListDictionaryInternal}
HResult: -2146233029
HelpLink: null
InnerException: {"Unable to read data from the transport connection: The I/O operation has been aborted because of either a thread exit or an application request."}
Message: "The operation was canceled."
Source: "System.Net.Http"
StackTrace: " at System.Net.Http.HttpConnection.<SendAsyncCore>d__61.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n at System.Net.Http.HttpConnectionPool.<SendWithNtConnectionAuthAsync>d__40.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n at System.Net.Http.HttpConnectionPool.<SendWithRetryAsync>d__39.MoveNext()\r\n at System.Runtime.ExceptionServices.Exce
ptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n at System.Net.Http.RedirectHandler.<SendAsync>d__4.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.DocumentClient.HttpRequestMessageHandler.<SendAsync>d__3.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.C
ompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()\r\n at System.Net.Http.HttpClient.<FinishSendAsyncBuffered>d__62.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.GatewayAccountReader.<GetDatabaseAccountAsync>d__8.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.Routing.GlobalEndpointManager.<GetDatabaseAccountFromAnyLocationsAsync>d__16.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuc
cess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.GatewayAccountReader.<InitializeReaderAsync>d__9.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.CosmosAccountServiceConfiguration.<InitializeAsync>d__36.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.DocumentClient.<InitializeGatewayConfigurationReaderAsync>d__309.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System
.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.DocumentClient.<GetInitializationTaskAsync>d__103.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.DocumentClient.<EnsureValidClientAsync>d__163.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.Handlers.RequestInvokerHandler.<EnsureValidClientAsync>d__9.MoveNext()\r\n at System.Runtime.ExceptionServices.Exceptio
nDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.Handlers.RequestInvokerHandler.<SendAsync>d__5.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.Handlers.RequestInvokerHandler.<SendAsync>d__7.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at Microsoft.Azure.Cosmos.CosmosResponseFactory.<ProcessMessageAsync>d__16`1.MoveNext()\r\n at System.Runtime.
ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n at Leaderboard_CosmosDB.Leaderboard_CosmosDB.<CreateDB>d__6.MoveNext() in C:\\Users\\Matthew\\source\\repos\\Leaderboard_CosmosDB\\Leaderboard_CosmosDB\\Leaderboard_CosmosDB.cs:line 89"
TargetSite: {Void MoveNext()}
Task: null
If I replace the storageURL and authKeyString in my local.settings.json file with a URL and key from a Cosmos DB instance running in Azure, the code works fine. Of course, I'd prefer to debug locally (and cost-free).
The Cosmos Emulator is running on the same machine as the function debugger. I am able to create a new database/container in the emulator using Data Explorer in a web browser running on the same machine.
This has happened to me on 2 different machines. It happens whether the Windows firewall is on or off.
What's the secret sauce to get a locally-debugged Azure function to connect to a local instance of Cosmos DB emulator?
EDIT: Others have asked for the full code of the function experiencing the problem. Here you are:
[FunctionName("CreateDB")]
public static async Task<string> CreateDB(
[HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = null)] HttpRequest req,
ILogger log,
ExecutionContext context)
{
string storageURL = "http://localhost:8081";
string authKeyString = "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==";
string dbName = "testDB";
string containerName = "testContainer");
string partitionKeyPath = "/partition");
CosmosClient client = new CosmosClient(storageURL, authKeyString);
try
{
Database oldDB = client.GetDatabase(dbName);
DatabaseResponse dbResp = await oldDB.DeleteAsync(); //Error is here
}
catch (Exception ex)
{
if (!ex.Message.Contains("Resource Not Found"))
{
return ("Error deleting old database: " + ex.Message);
}
}
try
{
DatabaseResponse dbresp = await client.CreateDatabaseAsync(dbName);
ContainerResponse cresp = await dbresp.Database.CreateContainerAsync(new ContainerProperties(containerName, partitionKeyPath));
}
catch (Exception ex)
{
return (ex.Message);
}
return ("OK");
}

Answer 1

Same environment, and I got a success.
Install Azure Cosmos Emulator
Get endpoint and key from emulator page
Create a sample console app
class Program
{
static void Main(string[] args)
{
string endpoint = "https://localhost:8081";
string key = "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==";
string databaseId = "TestDB";
string containerId = "TestContainer";
var client = new CosmosClient(endpoint, key);
var db = client.CreateDatabaseIfNotExistsAsync(databaseId).GetAwaiter().GetResult().Database;
var container = db.CreateContainerIfNotExistsAsync(containerId, "/partitionkey").GetAwaiter().GetResult().Container;
var result = container.CreateItemAsync(new { id = Guid.NewGuid(), partitionkey = "A", content = "Test" }).GetAwaiter().GetResult();
Console.WriteLine(result.StatusCode);
Console.ReadLine();
}
}
Result
From the result, you can see that I can successfully connect to emulator and create item. Please check your steps to see if there is anything wrong.