If a route already exists but is invalid (e.g. from a crash), we
automatically delete it before trying to create a route that would
otherwise conflict.
For AWS EBS, a volume can only be attached to a node in the same AZ.
The scheduler must therefore detect if a volume is being attached to a
pod, and ensure that the pod is scheduled on a node in the same AZ as
the volume.
So that the scheduler need not query the cloud provider every time, and
to support decoupled operation (e.g. bare metal) we tag the volume with
our placement labels. This is done automatically by means of an
admission controller on AWS when a PersistentVolume is created backed by
an EBS volume.
Support for tagging GCE PVs will follow.
Pods that specify a volume directly (i.e. without using a
PersistentVolumeClaim) will not currently be scheduled correctly (i.e.
they will be scheduled without zone-awareness).
General purpose SSD ('gp2') volume type is just slighly more expensive than
Magnetic ('standard' / default in AWS), while the performance gain is pretty
significant.
So far, the volumes were created only during testing, where the extra cost
won't make any difference. In future, we plan to introduce QoS classes, where
users could choose SSD/Magnetic depending on their use cases.
'gp2' is just the default volume type for (hopefuly) short period before these
QoS classes are implemented.
From some reason, MiBs were used for public functions and AWS cloud provider
recalculated them to GiB. Let's expose what AWS really supports and don't hide
real allocation units.
them, not in the steady state once they've been created. This makes it
much less likely that users will run into static IP quota issues.
Also add slightly more parallelism to the deletion of load balancers
now that I realize the static IPs can be deleted in parallel with
forwarding rules :)
Previously we'd just tear everything down and recreate it, which makes
for a pretty bad experience because it causes downtime whenever the
service controller restarts and has to make sure everything is in the
desired state.
This adds more code than I'd prefer, but makes it much cleaner and more
organized than it was before, in my opinion. I didn't bother
parallelizing anything because it's complex enough as it is, right now.
It's consistently passing the existing e2es and worked when I tested
manually, but this could definitely use additional e2e tests and/or some
serious refactoring to make real unit tests feasible. I'll follow up
with one or two e2e tests that make sense (updating an LB or killing the
controller manager, perhaps).
