EC2 plugin is not compatible with python2

[yonash2]

EC2 plugin does not work with python2 with the newest version of aws-xray-sdk-python (not sure in which version exactly this change was introduced, but it introduced this bug)

Opened this PR to fix it:
#249

[srprash]

HI @yonash2 . Thanks for bringing this issue to our notice. I'll look into the issue and review the PR as well. For starters, can you provide what's the error and the stack trace you get when using the EC2 plugin with python2?

As for the earlier change, it was done for defaulting to IMDS v2 endpoint since its more secure than v1 for fetching the EC2 metadata.

[yonash2]

Hi @srprash

Yeah that's, right, but my plan is not to revert that PR, or the IMDS v2 endpoint changes, but in that PR the order of install_aliases and import of urllib.request changed from urllib.request import urlopen, Request, resulting in this error in our builds:

[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/app/./manage.py", line 10, in <module>
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] execute_from_command_line(sys.argv)
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] utility.execute()
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/django/core/management/__init__.py", line 328, in execute
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] django.setup()
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/django/__init__.py", line 18, in setup
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] apps.populate(settings.INSTALLED_APPS)
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/django/apps/registry.py", line 115, in populate
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] app_config.ready()
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/aws_xray_sdk/ext/django/apps.py", line 39, in ready
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] stream_sql=settings.STREAM_SQL,
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/aws_xray_sdk/core/recorder.py", line 170, in configure
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] plugin_modules = get_plugin_modules(plugins)
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/aws_xray_sdk/core/plugins/utils.py", line 26, in get_plugin_modules
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] modules.append(importlib.import_module(full_path))
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] __import__(name)
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] File "/opt/prezi/virtualenv/lib/python2.7/site-packages/aws_xray_sdk/core/plugins/ec2_plugin.py", line 4, in <module>
[2020-11-23T06:19:12.965Z] [11/23/20_06:19:12] [build->handleAssets()] from urllib.request import urlopen, Request
[2020-11-23T06:19:13.226Z] [11/23/20_06:19:12] [build->handleAssets()] ImportError: No module named request

The problem is that in python2, this import won't work:

❯ python2
Python 2.7.18 (v2.7.18:8d21aa21f2, Apr 19 2020, 20:48:48)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from future.standard_library import install_aliases
>>> from urllib.request import urlopen, Request
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named request

unless the monkey patches described here are applied, which is done by calling install_aliases:

❯ python2
Python 2.7.18 (v2.7.18:8d21aa21f2, Apr 19 2020, 20:48:48)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from future.standard_library import install_aliases
>>> install_aliases()
>>> from urllib.request import urlopen, Request
>>>

[yonash2]

@srprash

is there anything I can do to move this forward?
I'd like to remove backpinning aws sdk from our packages

[srprash]

Hey @yonash2
Sorry it was my bad that the monkey patching order was not right in the change. Thanks for catching it. :)

I've merged the PR and will be out in the next release!

[yonash2]

@srprash No problem, mistakes happen to all of us, thanks a lot for reviewing and merging 🙏

[srprash]

As you might be aware that the python 2.7 has reached its end of life and is no longer supported. We would be dropping the support for python2 as well in the next major version of the SDK. You may want to upgrade to python3 to reap all the benefits.