KAFKA-3592: System test - configurable paths

[granders]

This patch adds logic for the following:

• remove hard-coded paths to various scripts and jars in kafkatest service classes
• provide a mechanism for overriding path resolution logic with a "pluggable" path resolver class

[granders]

@ewencp ping for initial review

There are some rough edges and unfinished bits, but It would be great to get feedback on the overall approach and path resolution api.

As we discussed offline recently, it's possible we want to change "path resolution" to something more general. From my vantage point, this is fairly extensible, but ideas here are welcome as well.

Note that running tests here relies on logic in the user-defined-globals branch of ducktape.

[ewencp]

If these can be overridden, should we remove the DEFAULT_ prefix?

[granders]

@ewencp Mind taking a quick look at the path resolution API again? I think it's cleaner now

[granders]

@ewencp I think this is ready for a more careful review now

[ewencp]

Why are these imports repeating version? It looks like that module only contains one child module.

[ewencp]

@granders Overall looks nice; easy transition without much overhead at each call. I'm having trouble running unit tests. First, I think we missed a memory_profiler dependency for the tests. Second, there is a reference to kafkatest_unit_test.directory_layout.check_project_paths where the kafkatest_unit_tests part of the path is missing the trailing s and there's an issue finding a template called sample. Also, you might want to go with something a bit less verbose (and less tab-completion-killing) than kafkatest_unit_tests. Maybe just tests/kafkatest/unit or something like that?

[ewencp]

Also, I assume we'll want to kick off a full test run before merging this since it's a pretty substantial change? And you might want to check pre- and post- patch --collect-only output to make sure we didn't accidentally lose any tests to syntax errors or anything like that.

[granders]

@ewencp Regarding unit tests - the kafkatest unit tests don't actually depend on memory_profiler, but the python setup.py test command seems to be picking up ducktape unit tests as well (which does require memory_profiler)

I'll try to fix this

[granders]

Running branch builder for further verification:
https://jenkins.confluent.io/job/system-test-kafka-branch-builder/427/console

Also - I don't see errors with --collect-only

[granders]

ping @ewencp
http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2016-05-05--002.1462515845--confluentinc--configurable-install-path--830c419/report.html

As far as I can tell digging into logs, these failures aren't related to path resolution changes

[ewencp]

LGTM, thanks!