langflow-ai/langflow · error · SystemExit

git is not available; cannot check append-only invariant.

Error message

git is not available; cannot check append-only invariant.

What it means

Raised by scripts/migrate/check_migration_append_only.py when it cannot invoke `git` (subprocess raises FileNotFoundError) while trying to `git show` the migration-table JSON at a baseline ref. The script compares current migration entries against the baseline to enforce append-only history; without git there is no baseline, so it exits rather than silently passing.

Source

Thrown at scripts/migrate/check_migration_append_only.py:75

def _git_show(ref: str, relpath: str) -> str | None:
    """Return the contents of ``relpath`` at ``ref``, or ``None`` if absent.

    Absence is the common-case on initial introduction of the table file:
    the baseline simply doesn't have the file yet, in which case there is
    nothing to compare against and the check trivially passes.
    """
    try:
        completed = subprocess.run(  # noqa: S603 - git invoked with a fixed argv list
            ["git", "show", f"{ref}:{relpath}"],  # noqa: S607 - git resolves via PATH like every CI runner
            check=False,
            capture_output=True,
            text=True,
            cwd=REPO_ROOT,
        )
    except FileNotFoundError:  # git not on PATH
        msg = "git is not available; cannot check append-only invariant."
        raise SystemExit(msg) from None
    if completed.returncode != 0:
        # Most likely: file not present at base ref.  We treat that as
        # "no baseline" and return None.
        return None
    return completed.stdout


def _parse(raw: str, *, source: str) -> tuple[list[dict], list[dict]]:
    """Return ``(entries, ambiguous_bare_names)`` from a migration-table JSON.

    Both lists default to empty when the field is absent so this script can
    compare across baselines that pre-date a given field.
    """
    try:
        data = json.loads(raw)
    except json.JSONDecodeError as exc:
        print(f"error: invalid JSON in {source}: {exc}", file=sys.stderr)
        raise SystemExit(2) from exc

View on GitHub (pinned to 976ec789d2)

Solutions

1. Install git in the environment (apt-get install -y git / apk add git) and re-run the script
2. Verify with `which git` in the exact shell/container the script runs in
3. If git is intentionally absent and no baseline is needed, export the repo without a .git directory — the script then treats it as 'no baseline' and passes trivially
4. In CI, use a base image that bundles git (e.g. ci- prefixed images)

Example fix

# before — Dockerfile with no git
FROM python:3.12-slim
RUN pip install -r requirements.txt

# after
FROM python:3.12-slim
RUN apt-get update && apt-get install -y --no-install-recommends git && rm -rf /var/lib/apt/lists/*
RUN pip install -r requirements.txt

import shutil
if shutil.which("git") is None:
    print("skipping append-only check: git not installed")
    sys.exit(0)  # or fail loudly, per your CI policy

# script already exits via SystemExit; wrap invocation instead:
import subprocess, sys
r = subprocess.run([sys.executable, "scripts/migrate/check_migration_append_only.py"])
if r.returncode != 0 and shutil.which("git") is None:
    print("pre-flight failed: install git in this image")

When it happens

Trigger: Running the migration check in an environment where git is not installed or not on PATH — minimal CI containers (python:slim without git), some Docker images, or restricted sandboxes — while the checkout includes a .git directory.

Common situations: CI images optimized to Python-only tooling; local venvs launched from GUI launchers that strip PATH; pipelines that archive the repo without .git (that yields the 'no baseline' pass, distinct from this).

Related errors

• error: invalid JSON in {source}: {exc}
• error: {source} top-level value must be an object
• error: {source} entries field must be a list
• error: {source} ambiguous_bare_names field must be a list
• module {__name__!r} has no attribute {attr_name!r}

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/90b3de7077d51ea0. Report an issue: GitHub.