Fix patching for PynamoDB 4.x with botocore 1.13

[Dunedan]

Fixes #179

Patching PynamoDB broke when using botocore 1.13, as this version of botocore doesn't ship requests anymore. While the vendored requests library is a requirement for PynamoDB <4.0, it's not for PynamoDB >=4.0. Therefore only import and patch botocore.vendored.requests.sessions when using PynamoDB <4.0.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[yan12125]

Ah, I happen to work on the same issue :) Maybe _xray_enabled should be added to botocore.httpsession for PynamoDB 4, like https://github.com/yan12125/aws-xray-sdk-python/commit/cc697afe4c18f15622c0348df5e0c3a383a9eecd?

There are still test failures. The reason might be incompatibility between aiobotocore and botocore >= 1.13 aio-libs/aiobotocore#743.

[Dunedan]

Maybe _xray_enabled should be added to botocore.httpsession for PynamoDB 4

I thought about that as well, but assumed there was a reason it wasn't added during the PynamoDB 4 commit. Anyway it seems to make sense, so I added it now.

There are still test failures. The reason might be incompatibility between aiobotocore and botocore >= 1.13 aio-libs/aiobotocore#743.

I focused on getting the PynamoDB patching to work again with botocore 1.13. I haven't looked too deep into the aiobotocore failures, but to me it seems like this doesn't require a change to aws-xray-sdk-python, but just a new version of aiobotocore.

[polamayster]

Just curious, what about pynamodb versions < 4.0 but with botocore >= 1.13 and removed vendored requests, wouldn't it fail with this fix?

[bhautikpip]

Hi @Dunedan,

Thanks for submitting this PR. Looks like few tests have failed because aiobotocore version is still making dependency on botocore.vendored.requests package. This does not require any change in aws-xray-python-sdk. Hopefully upcoming version of aiobotocore removes this dependency.

[Dunedan]

@polamayster I believe PynamoDB < 4.0 is simply not compatible with botocore >= 1.13, as the dependency on botocore.vendored.requests got just removed in PynamoDB 4.0.

[yan12125]

Now aiobotocore 0.11 is out with compatibility with new botocore, and aws-xray-sdk-python tests are green with that.

[codecov-io]

Codecov Report

Merging #181 into master will decrease coverage by 0.04%.
The diff coverage is 44.44%.

@@            Coverage Diff            @@
##           master    #181      +/-   ##
=========================================
- Coverage   83.44%   83.4%   -0.05%     
=========================================
  Files          77      77              
  Lines        2905    2910       +5     
=========================================
+ Hits         2424    2427       +3     
- Misses        481     483       +2

Impacted Files	Coverage Δ
aws_xray_sdk/ext/pynamodb/patch.py	76.08% <44.44%> (-6.84%)	⬇️
aws_xray_sdk/core/sampling/local/reservoir.py	100% <0%> (+11.11%)	⬆️

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[chanchiem]

Thank you very much for your contribution! This looks like a great fix :)