The Moby Project - a collaborative project for the container ecosystem to assemble container-based systems
7d7412f957
This patch attempts to allow endpoints to complete servicing connections while being removed from a service. The change adds a flag to the endpoint.deleteServiceInfoFromCluster() method to indicate whether this removal should fully remove connectivity through the load balancer to the endpoint or should just disable directing further connections to the endpoint. If the flag is 'false', then the load balancer assigns a weight of 0 to the endpoint but does not remove it as a linux load balancing destination. It does remove the endpoint as a docker load balancing endpoint but tracks it in a special map of "disabled-but-not- destroyed" load balancing endpoints. This allows traffic to continue flowing, at least under Linux. If the flag is 'true', then the code removes the endpoint entirely as a load balancing destination. The sandbox.DisableService() method invokes deleteServiceInfoFromCluster() with the flag sent to 'false', while the endpoint.sbLeave() method invokes it with the flag set to 'true' to complete the removal on endpoint finalization. Renaming the endpoint invokes deleteServiceInfoFromCluster() with the flag set to 'true' because renaming attempts to completely remove and then re-add each endpoint service entry. The controller.rmServiceBinding() method, which carries out the operation, similarly gets a new flag for whether to fully remove the endpoint. If the flag is false, it does the job of moving the endpoint from the load balancing set to the 'disabled' set. It then removes or de-weights the entry in the OS load balancing table via network.rmLBBackend(). It removes the service entirely via said method ONLY IF there are no more live or disabled load balancing endpoints. Similarly network.addLBBackend() requires slight tweaking to properly manage the disabled set. Finally, this change requires propagating the status of disabled service endpoints via the networkDB. Accordingly, the patch includes both code to generate and handle service update messages. It also augments the service structure with a ServiceDisabled boolean to convey whether an endpoint should ultimately be removed or just disabled. This, naturally, required a rebuild of the protocol buffer code as well. Signed-off-by: Chris Telfer <ctelfer@docker.com> |
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