Direct exec() the kubelet instead of launching in proc

[smarterclayton]

If only the kubelet is launched by the node process, execve(2) instead of launching in process. Requires some corrections to the upstream flags to support round tripping. Support OPENSHIFT_ALLOW_UNSUPPORTED_KUBELET=<path> to allow a kubelet binary that is not exactly equivalent (symlink or hardlink) to the current file. If the kubelet binary cannot be found, print a warning and continue with the in-proc flow (so we don't break older users without the kubelet symlink).

To start:

$ openshift start node --config=... --enable=kubelet --loglevel=3
<will log, then exec kubelet>
... kubelet logs

Networking can be run separately with:

$ openshift start network --config=...

Did a quick sanity test against this, didn't hit any obvious issues.

Builds off #16269

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[smarterclayton]

@deads2k here's the payoff

[smarterclayton]

@knobunc re our discussion today after this change openshift start network can now do all the networking on a node, and in theory could do so from a daemonset assuming the cni paths can be set correctly.

[deads2k]

please open the upstream upstream

[smarterclayton]

Yeah I still need to write a roundtripper for flags that catches this and a fuzzed On Sep 11, 2017, at 1:45 PM, David Eads <notifications@github.com> wrote: please open the upstream upstream — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#16270 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABG_pyX9bw6ZeS34uZT_auvkNS6h-7nVks5shXGvgaJpZM4PSMiL> .

[smarterclayton]

Note that this PR also exposes --v and --vmodule silently so that we are command line compatible with the upstreams.

[soltysh]

This lgtm, but I'd like to wait for upstream approval on the PR before merging this one.

[smarterclayton]

Upstream is approved.

[smarterclayton]

@openshift/sig-platform-inftrastructure @openshift/sig-user-interface anyone have any concerns about adding -v and -vmodule back in (not in completions or output)?

[smarterclayton]

I'm not hearing more comments?

[soltysh]

/lgtm

[openshift-merge-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: smarterclayton, soltysh

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[openshift-merge-robot]

Automatic merge from submit-queue (batch tested with PRs 16480, 16486, 16270, 16128, 16489)