* Kubelet uses a node's hostname as the node name, which isn't
resolvable on DigitalOcean. On DigitalOcean, the node name was
set to the internal IP until #337 switched to instead configuring
kube-apiserver to prefer the InternalIP for communication
* Explicitly configure etcd scrapes to target each controller by
internal IP and port 2381 (replace __address__)
* Heapster can now get nodes (i.e. kubelets) from the apiserver and
source metrics from the Kubelet authenticated API (10250) instead of
the Kubelet HTTP read-only API (10255)
* https://github.com/kubernetes/heapster/blob/master/docs/source-configuration.md
* Use the heapster service account token via Kubelet bearer token
authn/authz.
* Permit Heapster to skip CA verification. The CA cert does not contain
IP SANs and cannot since nodes get random IPs that aren't known upfront.
Heapster obtains the node list from the apiserver, so the risk of
spoofing a node is limited. For the same reason, Prometheus scrapes
must skip CA verification for scraping Kubelet's provided by the apiserver.
* https://github.com/poseidon/typhoon/blob/v1.12.1/addons/prometheus/config.yaml#L68
* Create a heapster ClusterRole to work around the default Kubernetes
`system:heapster` ClusterRole lacking the proper GET `nodes/stats`
access. See https://github.com/kubernetes/heapster/issues/1936
* If using --enable-ssl-passthrough or exposing TCP/UDP services,
be aware of https://github.com/kubernetes/ingress-nginx/pull/3038
* Workarounds until the fix merges are to stay on 0.17.1, use the
suggested development image, or revert to securityContext
`runAsNonRoot: false` for a while (less secure)
* node-exporter exposes metrics to Prometheus about total and
active md devices (e.g. disks in mdadm RAID arrays)
* Add alert that fires when a RAID disk fails or becomes inactive
for another reason
* Both flannel and Calico support host port via `portmap`
* Allows writing NetworkPolicies that reference ingress pods in `from`
or `to`. HostNetwork pods were difficult to write network policy for
since they could circumvent the CNI network to communicate with pods on
the same node.
* Use Kubelet bearer token authn/authz to scrape metrics
* Drop RBAC permission from nodes/proxy to nodes/metrics
* Stop proxying kubelet scrapes through the apiserver, since
this required higher privilege (nodes/proxy) and can add
load to the apiserver on large clusters
* A data volume (emptyDir) is mounted to /var/lib/prometheus
* Users could swap emptyDir for any desired volume if data
persistence is desired. Prometheus previously defaulted to
keeping its data in ./data relative to /prometheus. Override
this behavior to store data in /var/lib/prometheus
* Expose etcd metrics to workers so Prometheus can
run on a worker, rather than a controller
* Drop temporary firewall rules allowing Prometheus
to run on a controller and scrape targes
* Related to https://github.com/poseidon/typhoon/pull/175
* Use etcd v3.3 --listen-metrics-urls to expose only metrics
data via http://0.0.0.0:2381 on controllers
* Add Prometheus discovery for etcd peers on controller nodes
* Temporarily drop two noisy Prometheus alerts
