[PR] Ensure predictable mypy's type-checking rules in CI/CD

[kopf-archiver]

A pull request by nolar at 2019-12-07 11:30:30+00:00
Original URL: zalando-incubator/kopf#265
Merged by nolar at 2019-12-11 16:33:23+00:00

The type-checking rules should be predictable over time.

Issue : originally detected in #262, originally introduced in #200

Description

mypy

New mypy releases sometimes break the CI/CD builds when no significant code changes are introduced to the codebase. The CI/CD builds are expected to succeed as before.

Just happened in #262 — a documentation/CRD change, that got asyncio.wait() type-checks in kopf.reactor.running broken. A broken build: https://travis-ci.org/zalando-incubator/kopf/builds/620169471

Caused by a regression in mypy==0.750 with type inference (python/mypy#8051). The fix is going to be released 1 month after the regression was introduced: 21.11.2019 .. 16.12.2019. We cannot afford to wait 1 month with a broken CI/CD pipeline.

Previously, there were similar sudden changes in mypy with new rules in a new mypy release: e.g. #208.

It is expected that such backward-incompatible changes or regressions will be introduced in the future too — due to active development of mypy. So, since now, we keep the version pinned, and upgrade it explicitly as a separate PR (manual or maybe automatic) — possibly with relevant code changes to satisfy new type-checking rules.

urllib3

The urllib3 version ceiling was introduced in May 2019 in a256445 — due to setuptools/pkg_resources version conflicts and inability to run the CI/CD scripts. This ceiling was applied only to our own CI/CD. The apps were free to handle these issues their own way.

The issue seems to be fixed in psf/requests#5067 in April 2019.

Types of Changes

• Configuration change