roachtest: add support for subtests

[petermattis]

Fixes #23915

Release note: None

[cockroach-teamcity]

This change is 

[petermattis]

The first two commits are #25394. Feel free to review the whole kit and caboodle here.

I haven't been able to successfully run this remotely due to current wifi conditions.

[petermattis]

PS

~ roachtest run -n jepsen | grep RUN | wc -l
      78

[petermattis]

Fixed a bunch of small bugs this morning. Seems to be working. At least, I can run roachtest run jepsen/sequential and have only the sequential jepsen test run with the various nemeses and it only creates the cluster once.

[bdarnell]

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Review status: 0 of 6 files reviewed at latest revision, all discussions resolved.

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pkg/cmd/roachtest/jepsen.go, line 135 at r1 (raw file):

	// work around JSCH auth error: https://github.com/jepsen-io/jepsen/blob/master/README.md
	for _, ip := range workerIPs {
		host, _, err := net.SplitHostPort(ip)

InternalIP includes the port number? That's confusing. The method should be renamed to InternalAddr instead of InternalIP. Why didn't you need this for nodeFlags above?

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Comments from Reviewable

[petermattis]

Review status: 0 of 6 files reviewed at latest revision, 1 unresolved discussion.

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pkg/cmd/roachtest/jepsen.go, line 135 at r1 (raw file):

Previously, bdarnell (Ben Darnell) wrote…

InternalIP includes the port number? That's confusing. The method should be renamed to InternalAddr instead of InternalIP. Why didn't you need this for nodeFlags above?

I did need something similar for nodeFlags. I think you saw the output of a messed up rebased which accidentally dropped this from nodeFlags. I had a similar thought about InternalAddr when driving around just now. I've made that change.

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Comments from Reviewable

[petermattis]

bors r=bdarnell

[craig]

Build succeeded

• GitHub CI (Cockroach)