From 7f6f00f6ec4058b292fa70f35e296bb57f796a76 Mon Sep 17 00:00:00 2001
From: teknium1 <127238744+teknium1@users.noreply.github.com>
Date: Sun, 24 May 2026 18:32:14 -0700
Subject: [PATCH] test(dockerfile): accept s6-overlay /init as a known PID-1
 init
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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.
---
 tests/tools/test_dockerfile_pid1_reaping.py | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/tests/tools/test_dockerfile_pid1_reaping.py b/tests/tools/test_dockerfile_pid1_reaping.py
index 70d95807aa7..87856825f7d 100644
--- a/tests/tools/test_dockerfile_pid1_reaping.py
+++ b/tests/tools/test_dockerfile_pid1_reaping.py
@@ -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)."
     )