Add PyPI publish workflow and a helpful error when Sage is missing

Importing lmfdb.website (or lmfdb.app, or running the lmfdb script)
without SageMath now raises an ImportError explaining that the website
requires Sage and how to install into Sage's python, rather than a bare
ModuleNotFoundError, since pip cannot install Sage itself.

The publish workflow builds and twine-checks the sdist and wheel, smoke
tests the wheel, and uploads via PyPI trusted publishing: version tags
publish to PyPI, manual runs publish to TestPyPI as a dry run.  It cannot
succeed until psycodict is released on PyPI (PyPI rejects git URL
dependencies) and trusted publishing is configured; see the comments in
the workflow file.  Note that package versions must be PEP 440 compliant
(numeric release segments), so a letter-coded LMFDB version would need to
be mapped to its numeric form for the package.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: roed314

.github/workflows/publish.yml

@@ -0,0 +1,96 @@
+# Build the lmfdb package and publish it to PyPI.
+#
+# Triggers:
+#  - pushing a tag v<version> (e.g. v1.2.1) publishes to PyPI;
+#  - running the workflow manually (workflow_dispatch) publishes to
+#    TestPyPI, as a dry run.
+#
+# Before this can succeed, one-time setup is needed:
+#  - psycodict must be released on PyPI and the git dependency in
+#    pyproject.toml replaced by a normal versioned requirement (PyPI
+#    rejects packages whose dependencies are git URLs);
+#  - a "Trusted Publisher" must be configured for the lmfdb project on
+#    https://pypi.org (and https://test.pypi.org), pointing at this
+#    repository, this workflow file (publish.yml) and the environment
+#    names below (no API tokens are needed with trusted publishing);
+#  - (recommended) create "pypi" and "testpypi" environments in the
+#    repository settings, restricted to release tags/branches.
+#
+# Note on version numbers: the package version (pyproject.toml reads it
+# from lmfdb/version.py) must be PEP 440 compliant, i.e. numeric release
+# segments.  A letter-coded LMFDB version like 1.8.ba must be mapped to
+# its numeric form (1.8.26, via class_to_int) for the package; the tag
+# check below compares against the package version.
+
+name: Publish to PyPI
+
+on:
+  push:
+    tags: ["v*"]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Check that the tag matches the package version
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          package_version=$(python -c "import lmfdb.version; print(lmfdb.version.version)")
+          if [ "v${package_version}" != "${GITHUB_REF_NAME}" ]; then
+            echo "Tag ${GITHUB_REF_NAME} does not match lmfdb/version.py (${package_version})"
+            exit 1
+          fi
+
+      - name: Build sdist and wheel
+        run: |
+          python -m pip install build twine
+          python -m build
+          twine check dist/*
+
+      - name: Smoke test the wheel
+        run: |
+          python -m venv smoke
+          smoke/bin/pip install dist/*.whl
+          smoke/bin/python -c "import lmfdb, importlib.metadata; from lmfdb import db; assert not db.connected; print('wheel imports cleanly, version', importlib.metadata.version('lmfdb'))"
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: dist
+          path: dist/
+
+  publish-testpypi:
+    if: github.event_name == 'workflow_dispatch'
+    needs: build
+    runs-on: ubuntu-latest
+    environment: testpypi
+    permissions:
+      id-token: write
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: dist
+          path: dist/
+      - uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          repository-url: https://test.pypi.org/legacy/
+
+  publish-pypi:
+    if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+    needs: build
+    runs-on: ubuntu-latest
+    environment: pypi
+    permissions:
+      id-token: write
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: dist
+          path: dist/
+      - uses: pypa/gh-action-pypi-publish@release/v1

lmfdb/app.py

@@ -16,11 +16,14 @@
     url_for,
 )
 from markupsafe import escape
+
+# imported before sage so that a missing sage produces a helpful error message
+from .logger import critical
+
 from sage.env import SAGE_VERSION
 from sage.all import cached_function
 # acknowledgment page, reads info from lmfdb/CONTRIBUTORS.yaml
 
-from .logger import critical
 from .homepage import load_boxes, contribs
 
 from .version import version as _lmfdb_version

lmfdb/logger/start.py

@@ -2,7 +2,17 @@
                      INFO, WARNING,
                      info, warning)
 
-from sage.version import version as sage_version
+try:
+    from sage.version import version as sage_version
+except ModuleNotFoundError as e:
+    if e.name == "sage" or (e.name or "").startswith("sage."):
+        raise ImportError(
+            "The LMFDB website requires SageMath, which pip does not install.  "
+            "Install the LMFDB into Sage's Python, e.g. with `sage -pip install lmfdb` "
+            "(or `sage -pip install -e .` from a checkout).  "
+            "Database access (lmfdb.db) works without Sage."
+        ) from None
+    raise
 
 from .utils import LmfdbFormatter