Merge pull request #967 from sajith/3591.use-pip-cache-in-github-actions

Use pip cache in GitHub Actions

Fixes: ticket:3591

.github/workflows/ci.yml

@@ -30,17 +30,37 @@ jobs:
         with:
           args: install vcpython27
 
+      # See https://github.com/actions/checkout. A fetch-depth of 0
+      # fetches all tags and branches.
       - name: Check out Tahoe-LAFS sources
         uses: actions/checkout@v2
-
-      - name: Fetch all history for all tags and branches
-        run: git fetch --prune --unshallow
+        with:
+          fetch-depth: 0
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python-version }}
 
+      # To use pip caching with GitHub Actions in an OS-independent
+      # manner, we need `pip cache dir` command, which became
+      # available since pip v20.1+.  At the time of writing this,
+      # GitHub Actions offers pip v20.3.3 for both ubuntu-latest and
+      # windows-latest, and pip v20.3.1 for macos-latest.
+      - name: Get pip cache directory
+        id: pip-cache
+        run: |
+          echo "::set-output name=dir::$(pip cache dir)"
+
+      # See https://github.com/actions/cache
+      - name: Use pip cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.pip-cache.outputs.dir }}
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-
+
       - name: Install Python packages
         run: |
           pip install --upgrade codecov tox setuptools
@@ -103,15 +123,27 @@ jobs:
 
       - name: Check out Tahoe-LAFS sources
         uses: actions/checkout@v2
-
-      - name: Fetch all history for all tags and branches
-        run: git fetch --prune --unshallow
+        with:
+          fetch-depth: 0
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Get pip cache directory
+        id: pip-cache
+        run: |
+          echo "::set-output name=dir::$(pip cache dir)"
+
+      - name: Use pip cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.pip-cache.outputs.dir }}
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-
+
       - name: Install Python packages
         run: |
           pip install --upgrade tox
@@ -155,15 +187,27 @@ jobs:
 
       - name: Check out Tahoe-LAFS sources
         uses: actions/checkout@v2
-
-      - name: Fetch all history for all tags and branches
-        run: git fetch --prune --unshallow
+        with:
+          fetch-depth: 0
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Get pip cache directory
+        id: pip-cache
+        run: |
+          echo "::set-output name=dir::$(pip cache dir)"
+
+      - name: Use pip cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.pip-cache.outputs.dir }}
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-
+
       - name: Install Python packages
         run: |
           pip install --upgrade tox