test(dockerfile): accept s6-overlay /init as a known PID-1 init

Follow-up to @benbarclay's #30136 salvage. The pre-existing PID-1
contract tests in tests/tools/test_dockerfile_pid1_reaping.py (added
with #15012) hardcoded tini/dumb-init/catatonit as the only accepted
inits, so they failed after #30136 replaced tini with s6-overlay's
/init.

s6-overlay's PID 1 is s6-svscan, which reaps zombies non-blockingly
on SIGCHLD — same contract the test exists to enforce. Two updates:

  * test_dockerfile_installs_an_init_for_zombie_reaping — accept
    's6-overlay' as a known-installed marker (matches the
    s6-overlay install layer in Ben's Dockerfile).
  * test_dockerfile_entrypoint_routes_through_the_init — accept
    '/init' as a known-routed marker (s6-overlay's PID-1 binary
    lives at /init by convention).

Both assertions still fire if a future Dockerfile rewrite drops
the init entirely. Local: 7/7 pass.
This commit is contained in:
teknium1
2026-05-24 18:32:14 -07:00
parent 5cbb132c1d
commit 7f6f00f6ec

View File

@ -58,7 +58,7 @@ def _run_steps(dockerfile_text: str) -> list[str]:
def test_dockerfile_installs_an_init_for_zombie_reaping(dockerfile_text):
"""Some init (tini, dumb-init, catatonit) must be installed.
"""Some init (tini, dumb-init, catatonit, s6-overlay) must be installed.
Without a PID-1 init that handles SIGCHLD, hermes accumulates zombie
processes from MCP stdio subprocesses, git operations, browser
@ -66,8 +66,10 @@ def test_dockerfile_installs_an_init_for_zombie_reaping(dockerfile_text):
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")
# something must be installed that reaps orphans. s6-overlay was
# added in PR #30136 — its PID 1 is s6-svscan, which reaps zombies
# non-blockingly on SIGCHLD just like tini.
known_inits = ("tini", "dumb-init", "catatonit", "s6-overlay")
installed = any(name in dockerfile_text for name in known_inits)
assert installed, (
"No PID-1 init detected in Dockerfile (looked for: "
@ -80,8 +82,8 @@ def test_dockerfile_installs_an_init_for_zombie_reaping(dockerfile_text):
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
Installing an init is only half the fix — the container must actually run
with it 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.
"""
@ -96,11 +98,15 @@ def test_dockerfile_entrypoint_routes_through_the_init(dockerfile_text):
assert entrypoint_line is not None, "Dockerfile is missing an ENTRYPOINT directive"
known_inits = ("tini", "dumb-init", "catatonit")
# Accept any of the common inits as the first element of ENTRYPOINT.
# s6-overlay installs its PID-1 binary at ``/init`` (no path prefix
# — it's a hard-coded location for the overlay). PR #30136 swapped
# tini for s6-overlay, so ``/init`` is the canonical marker now.
known_inits = ("tini", "dumb-init", "catatonit", "/init")
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 "
"If an init is only installed but not wired into ENTRYPOINT, hermes "
"still runs as PID 1 and zombies will accumulate (#15012)."
)