How to specify EventHub Consumer Group in a WebJob? - azure

Question

I am using WebJob's bindings to EventHub as described here:
https://github.com/Azure/azure-webjobs-sdk/wiki/EventHub-support
While the webjob is running, trying to run the Azure Service Bus Explorer on the same hub result in this exception:
Exception: A receiver with a higher epoch '14' already exists. A new receiver with epoch 0 cannot be created.
Make sure you are creating receiver with increasing epoch value to ensure connectivity, or ensure all old epoch receivers are closed or disconnected.
From what I understand, this is caused by the 2 listeners(webjob & bus explorer) using the same Consumer Group.
So my question, how can I specify a different Consumer Group in my webjob ?
My current code look like this:
Program.cs:
var config = new JobHostConfiguration()
{
NameResolver = new NameResolver()
};
string eventHubConnectionString = ConfigurationManager.ConnectionStrings["EventHub"].ConnectionString;
string eventHubName = ConfigurationManager.AppSettings["EventHubName"];
string eventProcessorHostStorageConnectionString = ConfigurationManager.ConnectionStrings["EventProcessorHostStorage"].ConnectionString; ;
var eventHubConfig = new EventHubConfiguration();
eventHubConfig.AddReceiver(eventHubName, eventHubConnectionString, eventProcessorHostStorageConnectionString);
config.UseEventHub(eventHubConfig);
var host = new JobHost(config);
host.RunAndBlock();
Functions.cs:
public class Functions
{
public static void Trigger([EventHubTrigger("%EventHubName%")] string message, TextWriter log)
{
log.WriteLine(message);
}
}
[Edit - Bonus Question]
I don't fully grasp the use of Consumer Group and 'epoch' thing. One Consumer Group is limited to one receiver ?

Answer 1

The EventHubTrigger has an optional ConsumerGroup property (source). So, based on that modify the trigger like this:
public class Functions
{
public static void Trigger([EventHubTrigger("%EventHubName%", ConsumerGroup = "MyConsumerGroup")] string message, TextWriter log)
{
log.WriteLine(message);
}
}