Upgrade eventlet to the latest version (0.22.1)

[Kami]

This pull request upgrades eventlet to the latest stable version.

Some tests were failing with this version because of the removal of select.poll() method. To get it to pass, I added a work around which injects original select.poll() for tests.

This issue itself only affected tests.

We don't perform monkey patching in the subprocess which is used to execute Python runner actions - we tried to do monkey patching there in the past, but it negatively affected / didn't work with some 3rd party libraries so we decided to remove it and making it opt-in instead of being enabled by default.

Resolves #3968.

[Kami]

It looks like CI fails with a lot of errors, even though unit tests pass locally.

It looks like some of issues are related to the change in the DNS resolving.

[Kami]

@warrenvw @armab It looks like packages build is failing with:

File "/opt/stackstorm/st2/local/lib/python2.7/site-packages/eventlet/patcher.py", line 94, in inject
    module = __import__(module_name, {}, {}, module_name.split('.')[:-1])
  File "/opt/stackstorm/st2/local/lib/python2.7/site-packages/eventlet/support/dns/rdtypes/IN/WKS.py", line 23, in <module>
    _proto_tcp = socket.getprotobyname('tcp')
socket.error: protocol not found

New version of eventlet uses dnspython (async DNS library) by default which consults /etc/protocols file. I SSHed into the container and it looks like that file doesn't exist.

It looks like we should probably ensure this file exists and install netbase package on Ubuntu (http://senthilthecoder.com/post/ubuntu-getprotobyname/), wdyt?

[warrenvw]

Yes, install netbase.

[arm4b]

👍 to verify what @warrenvw said.

An addition to that, if minimal Docker image requires netbase apt package for st2 to function correctly, - we'll need to add it as a dependency in st2-packages for st2 (https://github.com/StackStorm/st2-packages/blob/master/packages/st2/debian/control#L16), as well as find the respective package name for rpm (if any).

[warrenvw]

FWIW, seems we need setup rpm package, not netcfg:

[vagrant@st2el7 ~]$ rpm -q --whatprovides /etc/protocols
setup-2.8.71-7.el7.noarch

[Kami]

Yay, looks like adding netbase as a dependency for st2 package fixed the build - https://circleci.com/gh/StackStorm/st2/6769

[m4dcoder]

LGTM. But the change is a little bit cryptic. Take InstallPackTestCase for example, i drilled down to https://github.com/StackStorm/st2/blob/master/contrib/packs/actions/pack_mgmt/download.py but I don't see any reference to eventlet and select poll. How is this failing?

[Kami]

@m4dcoder It's the underlying git library we use for git related operations - it shells out and uses .poll() method.

As mentioned in the description - this only affects tests where we use eventlet monkey patching, but not actual deployments, because we don't use monkey patching in the Python action runner subprocess.

[Kami]

And to clarify the test situation - there is actually no need for this and many other tests to use eventlet monkey patching, but the way the test runner works (multiple test files run in a single process) and the way eventlet monkey patching works (import side affect) it's sadly a side affect from some other test.

We had issues with this cross test side affects and pollution in the past, but sadly there is no easy way around it - running each test file in a separate process would be too slow and expensive.