fix(flask): response streaming

[mabdinur]

Description

• Blocked by: https://github.com/DataDog/dd-trace-py/pull/4303

• Use ddtrace wsgi middleware to trace flask applications. This ensures flask responses are traced and it's duration is captured in the flask.request span.

• Update flask test client to close response. This ensures the request and response spans are finished.

• Adds test case for response streaming in flask

• Update flask snapshots and tests to include flask.application and flask.response spans

Checklist

• [ ] Title must conform to conventional commit.
• [ ] Add additional sections for feat and fix pull requests.
• [ ] Ensure tests are passing for affected code.
• [ ] Library documentation and/or Datadog's documentation site is updated. Link to doc PR in description.

Motivation

Design

Testing strategy

Relevant issue(s)

Testing strategy

Reviewer Checklist

• [ ] Title is accurate.
• [ ] Description motivates each change.
• [ ] No unnecessary changes were introduced in this PR.
• [ ] PR cannot be broken up into smaller PRs.
• [ ] Avoid breaking API changes unless absolutely necessary.
• [ ] Tests provided or description of manual testing performed is included in the code or PR.
• [ ] Release note has been added for fixes and features, or else changelog/no-changelog label added.
• [ ] All relevant GitHub issues are correctly linked.
• [ ] Backports are identified and tagged with Mergifyio.
• [ ] Add to milestone.

[majorgreys]

Using a generator function raised session issues in SQLAlchemy.

@mabdinur can you include the relevant exception and traceback?

[codecov-commenter]

Codecov Report

Merging #4202 (0bbfbbc) into 1.x (fdcefa9) will decrease coverage by 0.04%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##              1.x    #4202      +/-   ##
==========================================
- Coverage   77.97%   77.92%   -0.05%     
==========================================
  Files         760      760              
  Lines       60288    60319      +31     
==========================================
- Hits        47007    47006       -1     
- Misses      13281    13313      +32     

Impacted Files	Coverage Δ
ddtrace/contrib/flask/patch.py	0.00% <0.00%> (ø)
tests/contrib/flask/__init__.py	0.00% <0.00%> (ø)
tests/contrib/flask/test_hooks.py	0.00% <0.00%> (ø)
tests/contrib/flask/test_request.py	0.00% <0.00%> (ø)
tests/contrib/flask/test_static.py	0.00% <0.00%> (ø)
...ts/contrib/flask_autopatch/test_flask_autopatch.py	0.00% <0.00%> (ø)
tests/utils.py	90.35% <0.00%> (-0.24%)	:arrow_down:

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[mergify[bot]]

@mabdinur this pull request is now in conflict 😩

[mergify[bot]]

backport 1.5 1.6

✅ Backports have been created

• #4624 feat(flask): response streaming (backport #4202) has been created for branch 1.5
• #4625 feat(flask): response streaming (backport #4202) has been created for branch 1.6

[mergify[bot]]

@mabdinur this pull request is now in conflict 😩

[ZStriker19]

It might be nice to see the same request flamegraph before and after for reference, but looking at the snapshots you can figure it out so just a nit.

[mergify[bot]]

@mabdinur this pull request is now in conflict 😩

[mergify[bot]]

@mabdinur this pull request is now in conflict 😩

[Kyle-Verhoog]

We should check the flask-poc system tests job to make sure we didn't break that. It looks like all the system tests jobs are failing though.