CODEWITHSUNDEEP
azure-service-fabric
Peter Lea
Peter Lea

Reputation: 1751

Fabric Service availability on start

I have a scenario where one of our services exposes WCF hosts that receive callbacks from an external service.

These hosts are dynamically created and there may be hundreds of them. I need to ensure that they are all up and running on the node before the node starts receiving requests so they don't receive failures, this is critical.

Is there a way to ensure that the service doesn't receive requests until I say it's ready? In cloud services I could do this by containing all this code within the OnStart method.

My initial thought is that I might be able to bootstrap this before I open the communication listener - in the hope that the fabric manager only sends requests once this has been done, but I can't find any information on how this lifetime is handled.

Upvotes: 0

Views: 142

Answers (1)

Vaclav Turecek
Vaclav Turecek

Reputation: 9050

There's no "fabric manager" that controls network traffic between your services within the cluster. If your service is up, clients or other services inside the cluster can choose to try to connect to it if they know its address. With that in mind, there are two things you have control over here:

The first is whether or not your service's endpoint is discoverable by other services or clients. This is the point at which your service endpoint is registered with Service Fabric's Naming Service, which occurs when your ICommunicationListener.OpenAsync method returns. At that point, the service endpoint is registered and others can discover it and attempt to connect to it. Of course you don't have to use the Naming Service or the ICommunicationListener pattern if you don't want to; your service can open up an endpoint whenever it feels like it, but if you don't register it with the Naming Service, you'll have to come up with your own service discovery mechanism.

The second is whether or not the node on which your service is running is receiving traffic from the Azure Load Balancer (or any load balancer if you're not hosting in Azure). This has less to do with Service Fabric and more to do with the load balancer itself. In Azure, you can use a load balancer probe to determine whether or not traffic should be sent to nodes.

EDIT: I added some info about the Azure Load Balancer to our documentation, hope this helps: https://azure.microsoft.com/en-us/documentation/articles/service-fabric-connect-and-communicate-with-services/

Upvotes: 1

Related Questions