feat: Add helper to git clone and tarball

The new helper `git_clone_and_tarball()` is an opinionated function to
clone a git repo from tag/ref with submodules and add the content into
a tar ball. The tar ball does not include a `.git` directory, but it
comes with a `.git_archival.txt` for `setuptools-scm`. An optional
callback can be used to rewrite clone URLs.

The base name of the tar ball and first-level directory are always based
on the `prefix` argument.

Signed-off-by: Christian Heimes <cheimes@redhat.com>

Author: tiran

src/fromager/gitutils.py

@@ -1,10 +1,17 @@
 import logging
+import os
 import pathlib
+import re
+import tarfile
+import tempfile
+import typing
 from urllib.parse import urlparse
 
 from packaging.requirements import Requirement
+from packaging.utils import canonicalize_name
+from packaging.version import Version
 
-from fromager import context, external_commands
+from . import context, external_commands, tarballs
 
 logger = logging.getLogger(__name__)
 
@@ -61,3 +68,257 @@ def git_clone(
         )
 
     return output_dir
+
+
+class BeforeSubmoduleCallback(typing.Protocol):
+    """Before submodule update callback"""
+
+    def __call__(self, *, clonedir: pathlib.Path, name: str, remote: str) -> None:
+        pass
+
+
+def git_clone_and_tarball(
+    *,
+    destdir: pathlib.Path,
+    prefix: tuple[Requirement, Version] | str,
+    repo_url: str,
+    tag: str | None = None,
+    ref: str | None = None,
+    before_submodule_update: BeforeSubmoduleCallback | None = None,
+    git_archival_tag_match: str | None = None,
+) -> pathlib.Path:
+    """Clone a git repository and generate a ball
+
+    This function creates a tar ball from a remote URL, with all submodules
+    (non-recursive), and includes a ``.git_archival.txt`` for setuptools-scm.
+
+    :param destdir: directory where the tar ball is stored
+    :param prefix: prefix of the tar ball and first level directory
+    :param repo_url: git clone url
+    :param tag: tag name to clone
+    :param ref: git ref to clone (mutually exclusive with *tag*)
+    :param before_submodule_update: callback that runs before
+        ``git submodule update``. The callback is execute for each submodule.
+    :param git_archival_tag_match: git describe tag pattern for ``.git_archival.txt``
+
+    This example code creates a ``xformers-0.0.31.post1.tar.gz`` tar ball:
+
+    .. code-block::
+
+       def cb(*, clonedir: pathlib.Path, name: str, remote: str) -> None:
+           subprocess.check_call(
+               ["git", "config", "set", f"submodule.{name}.url", mirror(remote)],
+               cwd=str(clonedir)
+           )
+
+       req = Requirement("xformers")
+       tag = "v0.0.31.post1"
+       version = Version(tag)
+       repo_url = "https://github.com/facebookresearch/xformers.git"
+       destdir = pathlib.Path("destdir").absolute()
+       tarball = git_clone_and_tarball(
+           prefix=(req, version),
+           destdir=destdir,
+           repo_url=repo_url,
+           tag=tag,
+           before_submodule_update=cb,
+       )
+    """
+    if isinstance(prefix, tuple):
+        req = prefix[0]
+        version = prefix[1]
+        assert isinstance(req, Requirement)
+        assert isinstance(version, Version)
+        canon_name = canonicalize_name(req.name)
+        prefix = f"{canon_name}-{version}"
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        clonedir = pathlib.Path(tmpdir).absolute()
+        _git_clone(
+            clonedir=clonedir,
+            repo_url=repo_url,
+            tag=tag,
+            ref=ref,
+        )
+        submodules = _git_submodule_list(clonedir=clonedir)
+        if before_submodule_update is not None:
+            for name, remote in submodules.items():
+                before_submodule_update(clonedir=clonedir, name=name, remote=remote)
+        _get_submodule_update(clonedir=clonedir)
+        _make_git_archival_txt(
+            clonedir=clonedir,
+            tag_match=git_archival_tag_match,
+        )
+        tarball = _create_tarball(
+            clonedir=clonedir,
+            destdir=destdir,
+            prefix=prefix,
+        )
+
+    return tarball
+
+
+def _git_clone(
+    *,
+    clonedir: pathlib.Path,
+    repo_url: str,
+    tag: str | None,
+    ref: str | None,
+) -> None:
+    """Clone a git repository into *clonedir*
+
+    Initializes submodules
+    """
+    if not bool(tag) ^ bool(ref):
+        raise ValueError("tag and ref are mutually exclusive")
+
+    # Create a clean URL without any credentials for logging
+    parsed_url = urlparse(repo_url)
+    clean_url = parsed_url._replace(netloc=parsed_url.hostname or "").geturl()
+    logger.info(f"cloning {clean_url}, tag {tag}, ref {ref}, into {clonedir}")
+
+    cmd: list[str] = ["git", "clone"]
+    if tag is not None:
+        # --branch works with branches and tags, but not with commits
+        cmd.extend(["--branch", tag, "--depth", "1"])
+    cmd.extend([repo_url, str(clonedir)])
+    external_commands.run(cmd, network_isolation=False)
+
+    # --branch only works with names, so we have to checkout the reference we
+    # actually want if it is not a name
+    if ref is not None:
+        external_commands.run(
+            ["git", "checkout", "--force", ref],
+            cwd=str(clonedir),
+            network_isolation=False,
+        )
+
+    # initialize submodule but do not fetch them, yet, to allow customization.
+    external_commands.run(
+        ["git", "submodule", "init"],
+        cwd=str(clonedir),
+        network_isolation=False,
+    )
+
+
+_SUBMODULE_RE = re.compile(r"^submodule\.(.*)\.url=(.*)$")
+
+
+def _git_submodule_list(*, clonedir: pathlib.Path) -> dict[str, str]:
+    """Get submodule mapping of name -> remote
+
+    Submodule must be initialized
+    """
+    out = external_commands.run(
+        ["git", "config", "list", "--local"],
+        cwd=str(clonedir),
+        network_isolation=False,
+    )
+    submodules = {}
+    for line in out.split("\n"):
+        if mo := _SUBMODULE_RE.match(line):
+            name, remote = mo.groups()
+            submodules[name] = remote
+    logger.debug(f"found submodules: {submodules}")
+    return submodules
+
+
+def _get_submodule_update(*, clonedir) -> None:
+    """Update and fetch submodules"""
+    external_commands.run(
+        ["git", "submodule", "update", "--force", "--depth", "1"],
+        cwd=str(clonedir),
+        network_isolation=False,
+    )
+
+
+def _make_git_archival_txt(
+    clonedir: pathlib.Path,
+    *,
+    tag_match: str | None = None,
+) -> str:
+    """Generate a .git_archival.txt file for setuptools-scm
+
+    https://setuptools-scm.readthedocs.io/en/latest/usage/#git-archives
+    """
+    if not tag_match:
+        tag_match = "*[0-9]*"
+    # ignore existing .git_archive.txt template
+    # TODO: Figure out how to use an existing file and replace its template variables.
+    archival = clonedir / ".git_archival.txt"
+    parts = [
+        "node: %H",  # commit hash
+        "node-date: %cI",  # commit date
+        f"describe-name: %(describe:tags=true,match={tag_match})",  # tag + commits since tags
+    ]
+    sep = "\n"  # cannot use backslash in f-strings on Python 3.11
+    out = external_commands.run(
+        [
+            "git",
+            "log",
+            f"--pretty=tformat:{sep.join(parts)}",
+            "-1",
+        ],
+        cwd=str(clonedir),
+        network_isolation=False,
+    )
+    archival.write_text(out)
+    logger.debug(f"Generated {archival} with content: \n{out}")
+    return out
+
+
+def _create_tarball(
+    *,
+    clonedir: pathlib.Path,
+    destdir: pathlib.Path,
+    prefix: str,
+) -> pathlib.Path:
+    """Create a tarball from a git checkout"""
+    # check for '/' in prefix
+    if os.sep in prefix:
+        raise ValueError(f"{prefix=} cannot contain {os.sep}")
+
+    tarball = destdir / f"{prefix}.tar.gz"
+    if tarball.is_file():
+        logger.debug(f"removing stale tar ball {tarball}")
+        tarball.unlink()
+
+    with tarfile.open(tarball, "x:gz", format=tarfile.PAX_FORMAT) as tar:
+        tarballs.tar_reproducible_with_prefix(
+            tar=tar,
+            basedir=clonedir,
+            prefix=prefix,
+            exclude_vcs=True,
+        )
+    return tarball
+
+
+def test():
+    logging.basicConfig(level=logging.DEBUG)
+
+    def cb(*, clonedir: pathlib.Path, name: str, remote: str) -> None:
+        print(name, remote)
+
+    if True:
+        tag = "v0.0.31.post1"
+        version = Version(tag)
+        req = Requirement("xformers")
+        repo_url = "https://github.com/facebookresearch/xformers.git"
+    else:
+        tag = "0.54.0"
+        version = Version(tag)
+        req = Requirement("fromager")
+        repo_url = "https://github.com/python-wheel-build/fromager.git"
+    destdir = pathlib.Path(".").absolute()
+    tarball = git_clone_and_tarball(
+        destdir=destdir,
+        prefix=(req, version),
+        repo_url=repo_url,
+        tag=tag,
+        before_submodule_update=cb,
+    )
+    print(tarball)
+
+
+if __name__ == "__main__":
+    test()

src/fromager/tarballs.py

@@ -4,6 +4,7 @@
 import pathlib
 import stat
 import tarfile
+import typing
 
 VCS_DIRS = {".bzr", ".git", ".hg", ".svn"}
 
@@ -24,6 +25,24 @@ def _tar_reset(tarinfo: tarfile.TarInfo) -> tarfile.TarInfo:
     return tarinfo
 
 
+def _tar_content(
+    *, basedir: pathlib.Path, exclude_vcs: bool = False
+) -> typing.Iterable[str]:
+    content: list[str] = [str(basedir)]  # include root
+    for root, dirs, files in os.walk(basedir):
+        if exclude_vcs:
+            # modify lists in-place, so os.walk does not descent into the
+            # excluded entries. git submodules have a `.git` file.
+            dirs[:] = [directory for directory in dirs if directory not in VCS_DIRS]
+            files[:] = [filename for filename in files if filename not in VCS_DIRS]
+        for directory in dirs:
+            content.append(os.path.join(root, directory))
+        for filename in files:
+            content.append(os.path.join(root, filename))
+    content.sort()
+    return content
+
+
 def tar_reproducible(
     tar: tarfile.TarFile,
     basedir: pathlib.Path,
@@ -39,21 +58,37 @@ def tar_reproducible(
     If ``exclude_vcs`` is True, then Bazaar, git, Mercurial, and subversion
     directories and files are excluded.
     """
-    content = [str(basedir)]  # convert from pathlib.Path, if that's what we have
-    for root, dirs, files in os.walk(basedir):
-        if exclude_vcs:
-            # modify lists in-place, so os.walk does not descent into the
-            # excluded entries. git submodules have a `.git` file.
-            dirs[:] = [directory for directory in dirs if directory not in VCS_DIRS]
-            files[:] = [filename for filename in files if filename not in VCS_DIRS]
-        for directory in dirs:
-            content.append(os.path.join(root, directory))
-        for filename in files:
-            content.append(os.path.join(root, filename))
-    content.sort()
-
+    content = _tar_content(basedir=basedir, exclude_vcs=exclude_vcs)
     for fn in content:
         # Ensure that the paths in the tarfile are rooted at the prefix
         # directory, if we have one.
         arcname = fn if prefix is None else os.path.relpath(fn, prefix)
         tar.add(fn, filter=_tar_reset, recursive=False, arcname=arcname)
+
+
+def tar_reproducible_with_prefix(
+    tar: tarfile.TarFile,
+    basedir: pathlib.Path,
+    prefix: str,
+    *,
+    exclude_vcs: bool = False,
+) -> None:
+    """Create reproducible tar file with a prefix
+
+    Add content from basedir to already opened tar. All archive names are
+    relative to ``basedir`` and with ``prefix` prepended. The ``prefix``
+    must be relative and can be ``.``. This is equivalent to
+    ``tar -czf $tarfile -C $basedir --transform 's,^,${prefix}/' .`` or
+    ``git archive --prefix ${prefix}/``.
+
+    If ``exclude_vcs`` is True, then Bazaar, git, Mercurial, and subversion
+    directories and files are excluded.
+    """
+    if os.sep in prefix:
+        raise ValueError("prefix {prefix} cannot contain {os.sep}")
+    content = _tar_content(basedir=basedir, exclude_vcs=exclude_vcs)
+    for fn in content:
+        # archive names are relative to basedir
+        # prefix is prepended and path is normalized
+        arcname = os.path.normpath(os.path.join(prefix, os.path.relpath(fn, basedir)))
+        tar.add(fn, filter=_tar_reset, recursive=False, arcname=arcname)

tests/test_tarballs.py

@@ -93,3 +93,19 @@ def test_vcs_exclude(tmp_path: pathlib.Path) -> None:
     with tarfile.open(t1, "r") as tf:
         names = tf.getnames()
     assert names == [str(p).lstrip(os.sep) for p in [root, root / "a"]]
+
+
+def test_tar_reproducible_with_prefix(tmp_path: pathlib.Path) -> None:
+    root = tmp_path / "root"
+    root.mkdir()
+    subdir = root / "subdir"
+    subdir.mkdir()
+    a = subdir / "a"
+    a.write_text("this is file a")
+
+    t1 = tmp_path / "out1.tar"
+    with tarfile.open(t1, "w") as tf:
+        tarballs.tar_reproducible_with_prefix(tar=tf, basedir=root, prefix="someprefix")
+    with tarfile.open(t1, "r") as tf:
+        names = tf.getnames()
+    assert names == ["someprefix", "someprefix/subdir", "someprefix/subdir/a"]