didericis-claude
61740cdb6a
Servers that don't offer ed25519 (ecdsa-only or rsa-only gitea instances) would raise "ssh-keyscan returned no ed25519 key" because `-t ed25519` produced no output. Remove the `-t ed25519` restriction: ssh-keyscan now returns all supported key types and the function picks the best available via _KEY_TYPE_PREFERENCE (ed25519 > ecdsa > rsa > first). Also adds four new fetch_host_key tests covering multi-type preference logic and updates the stale "no ed25519 key" assertion.
299 lines
10 KiB
Python
299 lines
10 KiB
Python
"""Preflight host-key population for git-gate upstreams (issue #333).
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When a git-gate repo entry lacks a `host_key`, this module either:
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- headless: dies with a clear config error.
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- interactive: fetches the key via ssh-keyscan, prompts the operator to
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confirm, and optionally persists it to the bottle config file on disk.
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Public entry point: `preflight_host_keys(manifest, headless=..., home_md=...)`.
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"""
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from __future__ import annotations
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import dataclasses
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import re
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import subprocess
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import sys
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from pathlib import Path
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from .log import die, info
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from .manifest import Manifest
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# Preferred key types, most secure first.
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_KEY_TYPE_PREFERENCE = (
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"ssh-ed25519",
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"ecdsa-sha2-nistp256",
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"ecdsa-sha2-nistp384",
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"ecdsa-sha2-nistp521",
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"ssh-rsa",
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)
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def fetch_host_key(host: str, port: str) -> str:
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"""Return an SSH public key for `host`:`port` via ssh-keyscan.
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Returns the key in `<type> <base64-data>` format (the host prefix is
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stripped so the result can be stored in `host_key` and later formatted
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into a known_hosts line by `git_gate_known_hosts_line`).
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Prefers ed25519 > ecdsa > rsa; falls back to the first key type
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returned if none of the preferred types are present.
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Raises `RuntimeError` on subprocess failure, timeout, or no result.
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Uses only the Python stdlib (subprocess)."""
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args = ["ssh-keyscan"]
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if port and port != "22":
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args += ["-p", port]
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args.append(host)
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try:
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result = subprocess.run(
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args, capture_output=True, text=True, timeout=15, check=False,
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)
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except OSError as e:
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raise RuntimeError(
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f"ssh-keyscan: could not launch for {host}:{port}: {e}"
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) from e
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except subprocess.TimeoutExpired as e:
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raise RuntimeError(f"ssh-keyscan timed out for {host}:{port}") from e
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# known_hosts format: "[host]:port type data" or "host type data"
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# Strip the host/port prefix; collect "type -> type data" by type.
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found: dict[str, str] = {}
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for line in result.stdout.splitlines():
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line = line.strip()
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if not line or line.startswith("#"):
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continue
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parts = line.split(None, 2)
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if len(parts) == 3 and parts[1] not in found:
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found[parts[1]] = f"{parts[1]} {parts[2]}"
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for preferred in _KEY_TYPE_PREFERENCE:
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if preferred in found:
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return found[preferred]
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if found:
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return next(iter(found.values()))
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raise RuntimeError(
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f"ssh-keyscan returned no host key for {host}:{port}."
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+ (f" stderr: {result.stderr.strip()!r}" if result.stderr.strip() else "")
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)
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# ---------------------------------------------------------------------------
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# Frontmatter text-level editing
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# ---------------------------------------------------------------------------
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def _insert_host_key_in_frontmatter(fm_text: str, repo_name: str, host_key: str) -> str:
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"""Append `host_key: <key>` to the named repo entry in raw frontmatter text.
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Locates the `<repo_name>:` block-mapping key, detects its child
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indentation from the sibling keys already present, and inserts the
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new line after the last child. Returns the original text if the
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repo entry is not found or already has a `host_key:` line."""
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lines = fm_text.splitlines(keepends=True)
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repo_pat = re.compile(r"^(\s+)" + re.escape(repo_name) + r"\s*:\s*(\r?\n)?$")
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repo_line_idx: int | None = None
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repo_indent: int | None = None
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for i, line in enumerate(lines):
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if repo_pat.match(line):
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repo_indent = len(line) - len(line.lstrip())
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repo_line_idx = i
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break
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if repo_line_idx is None or repo_indent is None:
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return fm_text
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child_indent: int | None = None
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last_child_idx = repo_line_idx
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for i in range(repo_line_idx + 1, len(lines)):
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raw = lines[i].rstrip("\r\n")
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if not raw.strip():
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continue
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indent = len(raw) - len(raw.lstrip())
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if indent > repo_indent:
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child_indent = indent
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last_child_idx = i
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else:
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break
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if child_indent is None:
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child_indent = repo_indent + 2
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block = "".join(lines[repo_line_idx + 1 : last_child_idx + 1])
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if re.search(r"^\s*host_key\s*:", block, re.MULTILINE):
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return fm_text
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new_line = " " * child_indent + f"host_key: {host_key}\n"
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lines.insert(last_child_idx + 1, new_line)
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return "".join(lines)
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def _update_frontmatter_in_file(file_text: str, repo_name: str, host_key: str) -> str:
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"""Apply `_insert_host_key_in_frontmatter` to the frontmatter section of
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a Markdown file, leaving the body unchanged. Returns the original text
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when no change is needed."""
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lines = file_text.splitlines(keepends=True)
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if not lines or lines[0].rstrip("\r\n") != "---":
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return file_text
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close_idx: int | None = None
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for i in range(1, len(lines)):
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if lines[i].rstrip("\r\n") == "---":
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close_idx = i
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break
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if close_idx is None:
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return file_text
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fm_text = "".join(lines[1:close_idx])
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body_text = "".join(lines[close_idx:])
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updated_fm = _insert_host_key_in_frontmatter(fm_text, repo_name, host_key)
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if updated_fm == fm_text:
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return file_text
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return "---\n" + updated_fm + body_text
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def _find_and_update_bottle_file(
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bottles_dir: Path, repo_name: str, host_key: str,
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) -> bool:
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"""Scan `bottles_dir/*.md` for the first file that directly declares
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`repo_name` without a `host_key`, update it, and return True.
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Walks files in sorted order so the result is deterministic. Does NOT
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follow `extends:` chains — only files that explicitly declare the repo
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entry are candidates. Returns False when no such file is found."""
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if not bottles_dir.is_dir():
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return False
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from .yaml_subset import YamlSubsetError, parse_frontmatter
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for path in sorted(bottles_dir.glob("*.md")):
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try:
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text = path.read_text(encoding="utf-8")
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fm, _body = parse_frontmatter(text)
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except (OSError, UnicodeDecodeError, YamlSubsetError):
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continue
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git_gate = fm.get("git-gate")
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if not isinstance(git_gate, dict):
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continue
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repos = git_gate.get("repos")
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if not isinstance(repos, dict):
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continue
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repo = repos.get(repo_name)
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if not isinstance(repo, dict):
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continue
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if repo.get("host_key"):
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continue
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updated = _update_frontmatter_in_file(text, repo_name, host_key)
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if updated == text:
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continue
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path.write_text(updated, encoding="utf-8")
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info(f"wrote host_key for {repo_name!r} to {path}")
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return True
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return False
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# ---------------------------------------------------------------------------
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# Interactive prompt helper
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# ---------------------------------------------------------------------------
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def _prompt_tty(message: str) -> str:
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"""Write `message` to stderr and read a line from /dev/tty (or stdin)."""
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sys.stderr.write(message)
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sys.stderr.flush()
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try:
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with open("/dev/tty", "r", encoding="utf-8") as tty:
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return tty.readline().rstrip("\n")
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except OSError:
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return sys.stdin.readline().rstrip("\n")
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# ---------------------------------------------------------------------------
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# Public API
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# ---------------------------------------------------------------------------
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def preflight_host_keys(
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manifest: Manifest,
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*,
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headless: bool,
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home_md: Path | None,
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) -> Manifest:
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"""Ensure every git-gate repo entry has a `host_key` configured.
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For entries whose `KnownHostKey` is empty:
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- headless: calls `die()` with a clear message naming the repos.
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- interactive: fetches the key via ssh-keyscan, shows it to the
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operator, and requests confirmation. If accepted, optionally
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persists it to the bottle config file on disk; the key is always
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applied in memory for this launch regardless of the persistence
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choice. Aborted confirmation calls `die()`.
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Returns a (possibly updated) Manifest. If all entries already have
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host keys the original manifest is returned unchanged."""
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bottle = manifest.bottle
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missing = [e for e in bottle.git if not e.KnownHostKey]
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if not missing:
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return manifest
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if headless:
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names = ", ".join(repr(e.Name) for e in missing)
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die(
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f"git-gate: no host_key configured for repo(s) {names}. "
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f"Add host_key to each bottle git-gate.repos entry, or run "
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f"interactively once to have it fetched and saved automatically."
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)
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bottles_dir = (home_md / "bottles") if home_md is not None else None
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updated_entries = list(bottle.git)
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for entry in missing:
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host = entry.UpstreamHost
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port = entry.UpstreamPort
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label = f"git-gate.repos[{entry.Name!r}]"
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info(f"{label}: no host_key configured; fetching from {host}:{port}")
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try:
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key = fetch_host_key(host, port)
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except RuntimeError as e:
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die(f"git-gate: {label}: {e}")
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sys.stderr.write(f"\ngit-gate: host key for {label}:\n {key}\n\n")
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confirm = _prompt_tty("Is this host key correct? [y/N] ")
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if confirm.strip().lower() not in ("y", "yes"):
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die(f"git-gate: {label}: host key not confirmed; aborting launch")
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if bottles_dir is not None:
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save = _prompt_tty(
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f"Save host_key for {entry.Name!r} to the bottle config file? [y/N] "
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)
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if save.strip().lower() in ("y", "yes"):
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ok = _find_and_update_bottle_file(bottles_dir, entry.Name, key)
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if not ok:
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sys.stderr.write(
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f"git-gate: {label}: bottle file not found or not writable; "
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f"host_key kept in memory for this session only\n"
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)
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idx = next(i for i, e in enumerate(updated_entries) if e.Name == entry.Name)
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updated_entries[idx] = dataclasses.replace(entry, KnownHostKey=key)
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updated_bottle = dataclasses.replace(bottle, git=tuple(updated_entries))
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return dataclasses.replace(manifest, bottle=updated_bottle)
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__all__ = [
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"fetch_host_key",
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"preflight_host_keys",
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"_insert_host_key_in_frontmatter",
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"_find_and_update_bottle_file",
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"_update_frontmatter_in_file",
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]
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