CI: run linters outside the container

Remove the dependency on the container so the lint job can run in
parallel with the build job. More time has to be spent installing
Python dependencies, but this is made up for by not having to download
and load the image artefact in addition to not having to wait for the
build job.

2 files changed, 44 insertions, 36 deletions

diff --git a/.github/workflows/lint.yaml b/.github/workflows/lint.yaml
index 111df54..5678f53 100644
--- a/.github/workflows/lint.yaml
+++ b/.github/workflows/lint.yaml
@@ -2,54 +2,66 @@ name: Lint
 
 on:
   workflow_call:
-    inputs:
-      artefact:
-        required: true
-        type: string
-      tag:
-        required: true
-        type: string
 
 jobs:
   lint:
     runs-on: ubuntu-latest
+    env:
+      PIP_DISABLE_PIP_VERSION_CHECK: 1
+      PIP_NO_CACHE_DIR: false
+      PIP_USER: 1  # Make dependencies install into PYTHONUSERBASE.
 
-    steps:
-      # region container setup
-      - name: Download image artefact
-        uses: actions/download-artifact@v2
-        with:
-          name: ${{ inputs.artefact }}
+      PIPENV_DONT_USE_PYENV: 1
+      PIPENV_HIDE_EMOJIS: 1
+      PIPENV_NOSPIN: 1
+
+      PYTHONUSERBASE: ${{ github.workspace }}/.cache/py-user-base
+      PRE_COMMIT_HOME: ${{ github.workspace }}/.cache/pre-commit-cache
 
-      - name: Load image from archive
-        run: docker load -i ${{ inputs.artefact }}.tar
+    steps:
+      - name: Add custom PYTHONUSERBASE to PATH
+        run: echo '${{ env.PYTHONUSERBASE }}/bin/' >> $GITHUB_PATH
 
-      # Needed for the Docker Compose file.
       - name: Checkout code
         uses: actions/checkout@v2
 
-      - name: Start container
-        run: |
-          export IMAGE_SUFFIX='-venv:${{ inputs.tag }}'
-          docker-compose up --no-build -d
-      # endregion
+      - name: Set up Python
+        id: python
+        uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
-      # Required by pre-commit.
-      - name: Install git
+      - name: Python dependency cache
+        uses: actions/cache@v2
+        id: python_cache
+        with:
+          path: ${{ env.PYTHONUSERBASE }}
+          key: "python-0-${{ runner.os }}-${{ env.PYTHONUSERBASE }}-\
+          ${{ steps.python.outputs.python-version }}-\
+          ${{ hashFiles('./Pipfile', './Pipfile.lock') }}"
+
+      # Install dependencies if there was a cache miss.
+      - name: Install Python dependencies
+        if: steps.python_cache.outputs.cache-hit != 'true'
         run: >-
-          docker exec snekbox_dev /bin/bash -c
-          'apt-get -y update && apt-get install -y git'
+          pip install pipenv==2021.11.23
+          && pipenv install --deploy --system --dev
+
+      - name: Pre-commit environment cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ env.PRE_COMMIT_HOME }}
+          key: "precommit-0-${{ runner.os }}-${{ env.PRE_COMMIT_HOME }}-\
+          ${{ steps.python.outputs.python-version }}-\
+          ${{ hashFiles('./.pre-commit-config.yaml') }}"
 
       # pre-commit's venv doesn't work with user installs.
       # Skip the flake8 hook because the following step will run it.
       - name: Run pre-commit hooks
         id: run-pre-commit-hooks
-        run: >-
-          docker exec snekbox_dev /bin/bash -c
-          'PIP_USER=0 SKIP=flake8 pre-commit run --all-files'
+        run: PIP_USER=0 SKIP=flake8 pre-commit run --all-files
 
-      - name: Show pre-commit logs
+      # Show the log to debug failures.
+      - name: Show pre-commit log
         if: always() && steps.run-pre-commit-hooks.outcome != 'success'
-        run: >-
-          docker exec snekbox_dev /bin/bash -c
-          'cat /root/.cache/pre-commit/pre-commit.log'
+        run: cat "${PRE_COMMIT_HOME}/pre-commit.log"
diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index cc8a1e0..3cdf940 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -11,10 +11,6 @@ jobs:
     uses: ./.github/workflows/build.yaml
   lint:
     uses: ./.github/workflows/lint.yaml
-    needs: build
-    with:
-      artefact: ${{ needs.build.outputs.artefact }}
-      tag: ${{ needs.build.outputs.tag }}
   test:
     uses: ./.github/workflows/test.yaml
     needs: build