Mypy static type checking workflow (stravalib/stravalib)

The Mypy static type checking workflow from stravalib/stravalib, explained and optimized by Latchkey.

CI health: D - needs work

Point runs-on at Latchkey and get caching, run de-duplication, job timeouts, self-healing for flaky steps, and up to 58% lower cost, applied automatically.

Grade your own workflow free or run it on Latchkey →

Source: stravalib/stravalib.github/workflows/type-check.ymlLicense Apache-2.0View source

What it does

This is the Mypy static type checking workflow from the stravalib/stravalib repository, a real project running GitHub Actions. It is shown here with attribution under its Apache-2.0 license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

workflow (.yml)

name: Mypy static type checking

on:
  pull_request:
  push:
    branches:
      - main

# Use bash by default in all jobs
defaults:
  run:
    shell: bash

permissions: {}

jobs:
  mypy:
    name: Run mypy
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false

    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          fetch-depth: 20
          persist-credentials: false
      - name: Set up Python 3.11
        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
        with:
          python-version: "3.11"
      - name: Set Variables
        id: set_variables
        shell: bash
        run: |
          echo "PY=$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')" >> $GITHUB_OUTPUT
          echo "PIP_CACHE=$(pip cache dir)" >> $GITHUB_OUTPUT
      - name: Cache dependencies
        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
        with:
          path: ${{ steps.set_variables.outputs.PIP_CACHE }}
          key: ubuntu-latest-pip-${{ steps.set_variables.outputs.PY }}
      - name: Install uv
        uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          python -m pip install nox
      - name: List installed packages
        run: python -m pip freeze
      - name: Run tests with mypy
        run: |
          nox -s mypy

The same workflow, on Latchkey

Estimated ~20% faster on cache hits, plus fewer wasted runs and a safer supply chain. Added and changed lines are highlighted.

name: Mypy static type checking
 
on:
  pull_request:
  push:
    branches:
      - main
 
# Use bash by default in all jobs
defaults:
  run:
    shell: bash
 
permissions: {}
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  mypy:
    timeout-minutes: 30
    name: Run mypy
    runs-on: latchkey-small
    strategy:
      fail-fast: false
 
    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          fetch-depth: 20
          persist-credentials: false
      - name: Set up Python 3.11
        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
        with:
          cache: 'pip'
          python-version: "3.11"
      - name: Set Variables
        id: set_variables
        shell: bash
        run: |
          echo "PY=$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')" >> $GITHUB_OUTPUT
          echo "PIP_CACHE=$(pip cache dir)" >> $GITHUB_OUTPUT
      - name: Cache dependencies
        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
        with:
          path: ${{ steps.set_variables.outputs.PIP_CACHE }}
          key: ubuntu-latest-pip-${{ steps.set_variables.outputs.PY }}
      - name: Install uv
        uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          python -m pip install nox
      - name: List installed packages
        run: python -m pip freeze
      - name: Run tests with mypy
        run: |
          nox -s mypy

What changed

Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
Cancel superseded runs when a branch or PR gets a newer push.
Cache dependency installs on the setup step so they are served from cache.
Add a job timeout so a hung step cannot burn hours of runner time.

What Latchkey heals here

This workflow has steps that commonly fail on transient issues (network, registries, flaky browsers). On Latchkey managed runners they are detected, retried, and self-healed instead of failing your build:

Dependency installs

This workflow runs 1 job per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow

actions/checkout actions/setup-python actions/cache astral-sh/setup-uv