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Scaling swarm-worker-vmss virtual machine scale set takes down the stack


(Msalvadores) #1

Expected behavior

I want to add more worker nodes and scale up one of my stack services. I would expect my stack to keep working while scaling up workers.

Actual behavior

When swarm-worker-vmss virtual machine scale starts resizing I loose connectivity to all the stack endpoints.

Steps to reproduce the behavior

1- Login into
2- Using Azure as a provider create a 1 Manager (VM DS4) and 4 Worker (VM DS3) swarm.
3- Once it is provisioned deploy a simple stack that exposes an HTTP endpoint.
4- Create a HTTP client that loops over calling one of the HTTP services. Leave it running forever.
5- Login into Portal Azure, navigate to the Swarm Resource Group, select the swarm-worker-vmss and scale to 10 workers.
6- The HTTP client in 4 dies with connections errors.
7- Retrying makes the client fail for a couple of minutes until the swarm services recover.

I have also reported this issue here: