Previously, once the executor is deleted for reasons (like upgrade or cluster scale-in),
the new executor deletes all existing resources created by the old executor and creates
new one. This mechanism becomes a problem when there are requests connecting to the
existing pods. Also in the worst case, the cluster may not have enough resources to create
new pods and cause service downtime.
This PR let each executor type adopts existing resources before starting the executor
API services, and so the alive connections won't experience failure. However, the requests
send to the function that doesn't have alive function pods will still fail due to the
executor is in bootstrapping.
For each ingress controller, the format of ingress host,
path and annotations are different. To support different
kinds of controller, this PR adds new ingress config field
to http trigger spec. A user can set annotations, host and
path based on the type of underlying ingress controller
with CLI.
Command example:
fission route create --name foo \
--url /foo/{bar} --function foofn --createingress \
--ingressannotation "nginx.ingress.kubernetes.io/ssl-redirect=false" \
--ingressannotation "nginx.ingress.kubernetes.io/use-regex=true" \
--ingressrule "*=/foo/*"
