Docker swarm mode rebalancing | Resurrection

[viveky4d4v]

Swarm mode

Rebalancing containers automatically when the node comes back in life . Kind of Resurrection .

Let's say if i have one manager & one worker .-

If worker dies , manager will schedule all containers on itself .
Worker comes back in life & manager doesn't rebalance containers & all containers sit on manager .
Now if manager dies , our stack goes down even if worker is up & running .
Ideally manager should automatically balance the containers when worker comes back in life by moving the oldest container back to the worker . I don't know how this can be done without downtime ( in case you have just one application container ) .
OR
if the scheduler makes some decision like in case of a single application container it should not move it back to worker to remove downtime but it should do it if we have multiple replicas.

PS - I understand it's not efficient way to use swarm, we should use at least 3 managers but i caught up in this situation so i thought to get some ideas from community.

[thaJeztah]

This is a duplicate of #24103; the reason behind this is that rebalancing actually can cause service interruption (i.e., why kill a healthy container?)

I don't know how this can be done without downtime ( in case you have just one application container ) .

Currently not, but there's some improvements made here; #30261

Even in that case, killing a task (container), and starting a new one may not always be seamless, depending on "what" is running in the container.

Now if manager dies , our stack goes down even if worker is up & running .

Your application would still fail if one of your containers is running on the manager; if the manager dies, no new containers will be started.

I'll close this issue, because it's a duplicate of #24103, but I hope the above explains a bit better why this is not implemented.

Feel free to continue the discussion after I closed