Currently hollow nodes communicate with kubemark master using public
master IP, which results in each call going through cloud NAT. Cloud NAT
limitations become performance bottleneck (see kubernetes/perf-tests/issues/874).
To mitigate this, in this change, a second kubeconfig called "internal"
is created. It uses private master IP and is used to set up hollow nodes.
Note that we still need the original kubemark kubeconfig (using public master IP)
to be able to communicate with the master from outside the cluster (when
setting it up or running tests).
Testing:
- set up kubemark cluster, verified apiserver logs to confirm that the call
from hollow nodes did not go through NAT
This removes setting KUBE_GCE_PRIVATE_CLUSTER=false flag when creating
kubemark master.
In result, util.sh detect-master function detects both private and
public master IPs. The comment about cloud NAT does not apply after
https://github.com/kubernetes/kubernetes/pull/81073/files got merged
(see comments in the PR discussion).
This is first PR to change kubemark clusters to use private master IPs:
https://github.com/kubernetes/perf-tests/issues/874.
Note that kubemark kubeconfig will still contain public master IP. This
will be addresses in the follow-up PRs.
Testing:
* set up kubemark cluster
* verified that both private and public kubemark master IPs are logged
* ran tests on kubemark cluster using cluster loader
This is equivalent to the "internal" firewall rule that is created for
the regular masters.
The main reason for doing it is to allow prometheus scraping metrics
from various kubemark master components, e.g. kubelet.
Ref. https://github.com/kubernetes/perf-tests/issues/503
