Files
hermes-agent/tests/tools/test_dockerfile_pid1_reaping.py
2026-04-27 10:15:00 -05:00

124 lines
4.3 KiB
Python

"""Contract tests for the container Dockerfile.
These tests assert invariants about how the Dockerfile composes its runtime —
they deliberately avoid snapshotting specific package versions, line numbers,
or exact flag choices. What they DO assert is that the Dockerfile maintains
the properties required for correct production behaviour:
- A PID-1 init (tini) is installed and wraps the entrypoint, so that orphaned
subprocesses (MCP stdio servers, git, bun, browser daemons) get reaped
instead of accumulating as zombies (#15012).
- Signal forwarding runs through the init so ``docker stop`` triggers
hermes's own graceful-shutdown path.
"""
from __future__ import annotations
from pathlib import Path
import pytest
REPO_ROOT = Path(__file__).resolve().parents[2]
DOCKERFILE = REPO_ROOT / "Dockerfile"
@pytest.fixture(scope="module")
def dockerfile_text() -> str:
if not DOCKERFILE.exists():
pytest.skip("Dockerfile not present in this checkout")
return DOCKERFILE.read_text()
def _dockerfile_instructions(dockerfile_text: str) -> list[str]:
instructions: list[str] = []
current = ""
for raw_line in dockerfile_text.splitlines():
line = raw_line.strip()
if not line or line.startswith("#"):
continue
current = f"{current} {line.removesuffix('\\').strip()}".strip()
if not line.endswith("\\"):
instructions.append(current)
current = ""
return instructions
def _run_steps(dockerfile_text: str) -> list[str]:
return [
instruction
for instruction in _dockerfile_instructions(dockerfile_text)
if instruction.startswith("RUN ")
]
def test_dockerfile_installs_an_init_for_zombie_reaping(dockerfile_text):
"""Some init (tini, dumb-init, catatonit) must be installed.
Without a PID-1 init that handles SIGCHLD, hermes accumulates zombie
processes from MCP stdio subprocesses, git operations, browser
daemons, etc. In long-running Docker deployments this eventually
exhausts the PID table.
"""
# Accept any of the common reapers. The contract is behavioural:
# something must be installed that reaps orphans.
known_inits = ("tini", "dumb-init", "catatonit")
installed = any(name in dockerfile_text for name in known_inits)
assert installed, (
"No PID-1 init detected in Dockerfile (looked for: "
f"{', '.join(known_inits)}). Without an init process to reap "
"orphaned subprocesses, hermes accumulates zombies in Docker "
"deployments. See issue #15012."
)
def test_dockerfile_entrypoint_routes_through_the_init(dockerfile_text):
"""The ENTRYPOINT must invoke the init, not the entrypoint script directly.
Installing tini is only half the fix — the container must actually run
with tini as PID 1. If the ENTRYPOINT executes the shell script
directly, the shell becomes PID 1 and will ``exec`` into hermes,
which then runs as PID 1 without any zombie reaping.
"""
# Find the last uncommented ENTRYPOINT line — Docker honours the final one.
entrypoint_line = None
for raw_line in dockerfile_text.splitlines():
line = raw_line.strip()
if line.startswith("#"):
continue
if line.startswith("ENTRYPOINT"):
entrypoint_line = line
assert entrypoint_line is not None, "Dockerfile is missing an ENTRYPOINT directive"
known_inits = ("tini", "dumb-init", "catatonit")
routes_through_init = any(name in entrypoint_line for name in known_inits)
assert routes_through_init, (
f"ENTRYPOINT does not route through an init: {entrypoint_line!r}. "
"If tini is only installed but not wired into ENTRYPOINT, hermes "
"still runs as PID 1 and zombies will accumulate (#15012)."
)
def test_dockerfile_installs_tui_dependencies(dockerfile_text):
assert "ui-tui/package.json" in dockerfile_text
assert "ui-tui/packages/hermes-ink/package-lock.json" in dockerfile_text
assert any(
"ui-tui" in step
and "npm" in step
and (" install" in step or " ci" in step)
for step in _run_steps(dockerfile_text)
)
def test_dockerfile_builds_tui_assets(dockerfile_text):
assert any(
"ui-tui" in step
and "npm" in step
and "run build" in step
for step in _run_steps(dockerfile_text)
)