allocator: Avoid assigning duplicate IPs during initialization by aaronlehmann · Pull Request #2237 · moby/swarmkit (original) (raw)
When the allocator starts up, there is a pass that "allocates" the
existing tasks/nodes/services in the store. In fact, existing tasks are
typically already allocated, and this is mostly populating local state
to reflect which IPs are taken. However, if there are any tasks in the
store which are brand new, or previously failed to allocated, these will
actually receive new allocations.
The problem is that allocation of new IPs is interspersed with updating
local state with existing IPs. If a task, node, or service that needs an
IP is processed before one that claims a specific IP, the IP claimed by
the latter task be assigned.
This change makes the allocator do two passes on initialization. First
it handles objects that claim a specific IP, then it handles all other
objects.