Previously, prometheus-adapter configuration wasn't taking into account
the scrape interval of kubelet, node-exporter and windows-exporter
leading to getting non fresh results, and even negative results from the
CPU queries when the irate() function was extrapolating data.
To fix that, we want to set the interval used in the irate() function in
the CPU queries to 4x scrape interval in order to extrapolate data
between the last two scrapes. This will improve the freshness of the cpu
usage exposed and prevent incorrect extrapolations.
Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>
Adding a PodDisruptionBudget to prometheus-adapter ensure that at least
one replica of the adapter is always available. This make sure that even
during disruption the aggregated API is available and thus does not
impact the availability of the apiserver.
Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>
Export the antiaffinity function of the anti-affinity addon to make it
possible to extend the addon to component that are not present in the
kube-prometheus stack.
Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>
Prometheus-adapter is a component of the monitoring stack that in most
cases require to be highly available. For instance, we most likely
always want the autoscaling pipeline to be available and we also want to
avoid having no available backends serving the metrics API apiservices
has it would result in both the AggregatedAPIDown alert firing and the
kubectl top command not working anymore.
In order to make the adapter highly-avaible, we need to increase its
replica count to 2 and come up with a rolling update strategy and a
pod anti-affinity rule based on the kubernetes hostname to prevent the
adapters to be scheduled on the same node. The default rolling update
strategy for deployments isn't enough as the default maxUnavaible value
is 25% and is rounded down to 0. This means that during rolling-updates
scheduling will fail if there isn't more nodes than the number of
replicas. As for the maxSurge, the default should be fine as it is
rounded up to 1, but for clarity it might be better to just set it to 1.
For the pod anti-affinity constraints, it would be best if it was hard,
but having it soft should be good enough and fit most use-cases.
Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>
Replace Watchdog alerts part of the `example-group` in some examples by
ExampleAlert alerts to reinforce the fact that this is just an example.
Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>
Damien Grisonnet
