Hi all,
At the Kolla meeting last week, I brought up some of the challenges around the
bootstrapping
process in Kubernetes. The main highlight revolved around how the
bootstrapping process will
work.
Currently, in the kolla-kubernetes spec [1], the process for bootstrapping
involves
outside orchestration running Kubernetes 'Jobs' that will handle the database
initialization,
creating users, etc... One of the flaws in this approach, is that
kolla-kubernetes can't use
native Kubernetes upgrade tooling. Kubernetes does upgrades as a single action
that scales
down running containers and replaces them with the upgraded containers. So
instead of having
Kubernetes manage the upgrade, it would be guided by an external engine. Not
saying this is
a bad thing, but it does loosen the control Kubernetes would have over stack
management.
Kubernetes does have some incoming new features that are a step in the right
direction to
allow for kolla-kubernetes to make complete use of Kubernetes tooling like init
containers [2].
There is also the introduction to wait.for conditions in the kubectl [3].
kubectl get pod my-pod --wait --wait-for="pod-running"
Upgrades will be in the distant future for kolla-kubernetes, but I want to make
sure the
community maintains an open mind about bootstrap/upgrades since there are
potentially many
options that could come down the road.
I encourage everyone to add your input to the spec!
Thanks,
Ryan
[1] SPEC - https://review.openstack.org/#/c/304182/
[2] Init containers - https://github.com/kubernetes/kubernetes/pull/23567
[3] wait.for kubectl - https://github.com/kubernetes/kubernetes/issues/1899
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