Existing code has been used for scaling up and querying replicas.
This meant the new code was deleted and there is less duplication
now.
The cache store a whole query response rather than just the
available replica count and the tests were updated. This has been
tested with Docker swarm and the image:
openfaas/gateway:scale-17-07-2018
This feature now needs the env-var of scale_from_zero to be enabled
in order to turn on the scaling behaviour.
Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>
This change allows functions to be "idled" or scaled to zero
replicas and then be invoked later on. There is a penalty to
scaling up - the API gateway proxy will block until the function
is ready.
A cache is included to off-set the calls to upstream API to check
on readiness along with unit tests.
Testing via scaling to zero replicas and then invoking function.
On Swarm I observed 3 seconds on an Intel Nuc i5 for scaling back
from zero replicas.
Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>
