k8s: Support StatefulSet and PersistentVolume in Helm chart

[enisoc]

@thompsonja

Note that this only works in a k8s 1.4 cluster with alpha features enabled (i.e. not in a production GKE cluster). After k8s 1.5, we can update this to use the beta StatefulSet.

[thompsonja-bot]

Reviewed 1 of 1 files at r1, 3 of 4 files at r2, 1 of 3 files at r3, 1 of 2 files at r4.
Review status: 6 of 7 files reviewed at latest revision, 2 unresolved discussions.

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helm/vitess/templates/_vtctld.tpl, line 62 at r2 (raw file):

          resources:
{{ toYaml (.resources | default $0.resources) | indent 12 }}
          securityContext:

What is the purpose of this?

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helm/vitess/templates/_vtctld.tpl, line 69 at r2 (raw file):

            - |
              set -ex
              eval exec /vt/bin/vtctld $(cat <<END_OF_COMMAND

Why eval exec?

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Comments from Reviewable

[thompsonja-bot]

Reviewed 1 of 2 files at r4.
Review status: all files reviewed at latest revision, 2 unresolved discussions.

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Comments from Reviewable

[enisoc]

The securityContext tells k8s to launch the container as user "vitess" (created in the Dockerfile), so we don't need the su command anymore.

The $(cat <<HEREDOC) subshell is there to put all those flags on one line. It avoids the need to end each line with \, which we've seen is error-prone and frustrating to debug.

After being put on one line, however, it all gets treated as a literal string, so things like -flag="quoted value" don't get transformed through the usual shell semantics into the literal argv element -flag=quoted value. The eval tells the shell to take another pass at doing these transformations.

[thompsonja-bot]

LGTM.

I hadn't notice the quotes change, eval makes total sense :)

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Review status: all files reviewed at latest revision, 2 unresolved discussions.

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Comments from Reviewable

[thompsonja-bot]

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Review status: all files reviewed at latest revision, 2 unresolved discussions.

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Comments from Reviewable