ci: run the smoke tests on a schedule

.github/workflows/smoke.yaml

@@ -0,0 +1,68 @@
+name: ops Smoke Tests
+
+on:
+  workflow_dispatch:
+    schedule:
+      - cron:  '0 7 25 * *'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        # pylibjuju does not currently support Juju 4.x
+        # The smoke tests do not yet work on Juju 2.9.
+        juju-version: ['3.5']
+        charmcraft-version: ['2.x', '3.x']
+        cloud: ['lxd', 'microk8s']
+
+    env:
+      JUJU_VERSION: "${{ matrix.juju-version }}"
+
+    steps:
+      # LXD is required for charmcraft to pack, even if it's not used as the
+      # Juju cloud.
+      - name: Set up LXD
+        uses: canonical/setup-lxd@8fb85546a934dfb994becf81341dd387ffe6aabb
+        with:
+          channel: 5.0/stable
+
+      - name: Set up Microk8s
+        if: matrix.cloud == 'microk8s'
+        uses: balchua/[email protected]
+        with:
+          channel: '1.26-strict/stable'
+          devMode: 'true'
+          addons: '["dns", "hostpath-storage"]'
+
+      - name: Set up Juju (classic)
+        if: matrix.juju-version == '2.9'
+        run: sudo snap install juju --classic --channel=${{ matrix.juju-version }}
+
+      - name: Set up Juju
+        if: matrix.juju-version != '2.9'
+        run: sudo snap install juju --channel=${{ matrix.juju-version }}
+
+      - name: Bootstrap Juju controller (k8s)
+        if: matrix.cloud == 'microk8s'
+        run: sg snap_microk8s -c 'juju bootstrap microk8s'
+
+      - name: Bootstrap Juju controller (lxd)
+        if: matrix.cloud == 'lxd'
+        run: juju bootstrap localhost
+
+      - name: Install charmcraft
+        run: sudo snap install charmcraft --channel=${{ matrix.charmcraft-version }} --classic
+
+      - name: Checkout the repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python 3
+        uses: actions/setup-python@v5
+
+      - name: Install tox
+        run: pip install tox~=4.2
+
+      - name: Run smoke tests
+        run: tox -e smoke

test/smoke/test_smoke.py

@@ -14,7 +14,11 @@
 #
 # Learn more about testing at: https://juju.is/docs/sdk/testing
 
+import grp
 import logging
+import os
+import pathlib
+import subprocess
 
 import pytest
 from pytest_operator.plugin import OpsTest
@@ -45,6 +49,33 @@
 """
 
 
+def pack(charm_dir: pathlib.Path):
+    """Pack the charm.
+
+    The pytest-operator plugin has a pack method, but it doesn't work out of the
+    box in GitHub actions, and there isn't really any reason that it should be
+    part of the plugin, so we just have a simple subprocess here.
+    """
+    cmd = ['charmcraft', 'pack', '--verbose']
+    # We need to use `sudo` in the GitHub actions environment, just as in
+    # the pack test. `sg lxd -c` should work, but does not - perhaps because of
+    # the way we are installing LXD?
+    if 'lxd' not in {grp.getgrgid(g).gr_name for g in os.getgroups()}:
+        cmd.insert(0, 'sudo')
+
+    logger.info('Building charm with %r', cmd)
+    subprocess.run(cmd, cwd=charm_dir, check=True)
+    logger.info('Built charm')
+
+    # Move the packed charm to the charm directory.
+    dest_name = None
+    for charm in charm_dir.glob('*.charm'):
+        dest_name = charm_dir / charm.name
+        charm.rename(dest_name)
+    # With the way we use charmcraft, we know that there will only be one.
+    return dest_name.absolute()
+
+
 @pytest.mark.parametrize(
     'base,charmcraft_version,name',
     (
@@ -55,13 +86,23 @@
 )
 async def test_smoke(ops_test: OpsTest, base: str, charmcraft_version: int, name: str):
     """Verify that we can build and deploy charms from supported bases."""
+    available_charmcraft_version = (
+        subprocess.run(['charmcraft', 'version'], check=True, capture_output=True)  # noqa: S607
+        .stdout.decode()
+        .strip()
+        .rsplit()[-1]
+        .split('.')
+    )
+    if int(available_charmcraft_version[0]) < charmcraft_version:
+        pytest.skip(f'charmcraft version {available_charmcraft_version} is too old for this test')
+        return
     charmcraft_yaml = {
         2: CHARMCRAFT2_YAML,
         3: CHARMCRAFT3_YAML,
     }[charmcraft_version].format(base=base)
     with open('./test/charms/test_smoke/charmcraft.yaml', 'w') as outf:
         outf.write(charmcraft_yaml)
-    charm = await ops_test.build_charm('./test/charms/test_smoke/')
+    charm = pack(pathlib.Path('./test/charms/test_smoke/'))
 
     app = await ops_test.model.deploy(
         charm, base=f'ubuntu@{base}', application_name=f'{name}-smoke'

tox.ini

@@ -136,6 +136,7 @@ description = Run a smoke test against a Juju controller.
 allowlist_externals = juju
                       charmcraft
                       bash
+passenv = JUJU_VERSION
 deps =
     build
     coverage[toml]~=7.0
@@ -147,6 +148,8 @@ commands =
     python -m build --sdist --outdir={toxinidir}/test/charms/test_smoke/
     # Inject the tarball into the smoke test charm's requirements.
     bash -c 'echo "./$(ls -1 ./test/charms/test_smoke/ | grep tar.gz)" > ./test/charms/test_smoke/requirements.txt'
+    # If a specific Juju version is set, then make sure we are using that version of pylibjuju.
+    bash -c 'if [ -n "$JUJU_VERSION" ]; then pip install "juju ~= $JUJU_VERSION"; fi'
 
     # Run our smoke tests (this will build the charm, then run the tests).
     pytest -v --tb native --log-cli-level=INFO -s {posargs} {toxinidir}/test/smoke/