This is the heart of the scalability change for services in libnetwork.
The present routing mesh adds load-balancing rules for a network to
every container connected to the network. This newer approach creates a
load-balancing endpoint per network per node. For every service on a
network, libnetwork assigns the VIP of the service to the endpoint's
interface as an alias. This endpoint must have a unique IP address in
order to route return traffic to it. Traffic destined for a service's
VIP arrives at the load-balancing endpoint on the VIP and from there,
Linux load balances it among backend destinations while SNATing said
traffic to the endpoint's unique IP address.
The net result of this scheme is that each node in a swarm need only
have one set of load balancing state per service instead of one per
container on the node. This scheme is very similar to how services
currently operate on Windows nodes in libnetwork. It (as with Windows
nodes) costs the use of extra IP addresses in a network (one per node)
and an extra network hop in the stack, although, always in the stack
local to the container.
In order to prevent existing deployments from suddenly failing if they
failed to allocate sufficient address space to include per-node
load-balancing endpoint IP addresses, this patch preserves the existing
functionality and activates the new functionality on a per-network
basis depending on whether the network has a load-balancing endpoint.
Eventually, moby should always set this option when creating new
networks and should only omit it for networks created as part of a swarm
that are not marked to use endpoint load balancing.
This patch also normalizes the code to treat "load" and "balancer"
as two separate words from the perspectives of variable/function naming.
This means that the 'b' in "balancer" must be capitalized.
Signed-off-by: Chris Telfer <ctelfer@docker.com>
This was passing extra information and adding confusion about the
purpose of the load balancing structure.
Signed-off-by: Chris Telfer <ctelfer@docker.com>
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>
- Do not relay on software flags to decide when to create the
virtual service. Instead query the kernel for presence.
So that it cannot happen that a real server creation
fails because the virtual server is missing.
Signed-off-by: Alessandro Boch <aboch@docker.com>
1. Base work was done by msabansal and nwoodmsft
from : https://github.com/msabansal/docker/tree/overlay
2. reorganized under drivers/windows/overlay and rebased to
libnetwork master
3. Porting overlay common fixes to windows driver
* 46f525c
* ba8714e
* 6368406
4. Windows Service Discovery changes for swarm-mode
5. renaming default windows ipam drivers as "windows"
Signed-off-by: Madhu Venugopal <madhu@docker.com>
Signed-off-by: msabansal <sabansal@microsoft.com>
Signed-off-by: nwoodmsft <Nicholas.Wood@microsoft.com>
