Flaky test: TestManagerLockUnlock

[aaronlehmann]

https://circleci.com/gh/docker/swarmkit/7215

--- FAIL: TestManagerLockUnlock (0.22s)
	Error Trace:	manager_test.go:404
	Error:		Should be false

cc @cyli

[cyli]

Huh, the:

time="2017-05-12T23:11:32Z" level=error msg="failed to re-encrypt TLS key with a new KEK" error="rename /tmp/swarm-ca-test-812740986/.tmp-swarm-node.key604794867 /tmp/swarm-ca-test-812740986/swarm-node.key: no such file or directory" node.id=ygqdkaoi7pnbmkcpat8gmvovi node.role=swarm-manager 
time="2017-05-12T23:11:32Z" level=error msg="failed to re-encrypt TLS key with a new KEK" error="open /tmp/swarm-ca-test-812740986/swarm-node.key: no such file or directory" node.id=ygqdkaoi7pnbmkcpat8gmvovi node.role=swarm-manager 
time="2017-05-12T23:11:32Z" level=error msg="failed to re-encrypt TLS key with a new KEK" error="open /tmp/swarm-ca-test-812740986/swarm-node.key: no such file or directory" node.id=ygqdkaoi7pnbmkcpat8gmvovi node.role=swarm-manager 

right after the test is weird too

[Syntaxide]

@aaronlehmann How often do you see this failure? There doesn't seem to be a good way to search for this on circleci.

[aaronlehmann]

I don't recall seeing this since the original report.

[cyli]

I haven't seen this in a while, and I haven't been able to replicate it easily (I've been running the test over and over in a container somewhere, and can continue to do so until it triggers, but it hasn't yet)

[cyli]

Just as a note, this may have been due to #2281, although it'd be good to try to replicate this still. My attempt to replicate crashed. :P So trying again

[Syntaxide]

I ran this test repeatedly on my laptop for over a week, and found that it ran roughly 10k times without failing. If this test is indeed flaky, it will be more productive to try to isolate the cause of the failure, rather than hoping to catch the flake naturally.

[cyli]

I think this was fixed by #2575.