is_container() detection accuracy: false positives and misses

Fixes on record

Merged to main. A stamp counts the issues a fix is linked to.

• #47131 fix(cli): detect containerd/CRI cgroup-v2 containers in is_container()

  merged to main

  files: hermes_constants.py, tests/test_hermes_constants.py

  Show the diff

  • hermes_constants.py

    @@ -461,11 +461,21 @@ def is_wsl() -> bool:
     
     
     def is_container() -> bool:
    -    """Return True when running inside a Docker/Podman container.
    +    """Return True when running inside a container.
     
    -    Checks ``/.dockerenv`` (Docker), ``/run/.containerenv`` (Podman),
    -    and ``/proc/1/cgroup`` for container runtime markers.  Result is
    -    cached for the process lifetime.  Import-safe — no heavy deps.
    +    Recognizes Docker (``/.dockerenv``), Podman (``/run/.containerenv``),
    +    and — via ``/proc/1/cgroup`` — the docker/podman/lxc cgroup-v1 markers.
    +
    +    cgroup v2 collapses ``/proc/1/cgroup`` to a single ``0::/`` line with no
    +    runtime marker, so containerd/CRI-O runtimes (the common case on
    +    Kubernetes/k3s) were previously missed. To cover those, also check:
    +      * ``KUBERNETES_SERVICE_HOST`` env var — set in every Kubernetes pod.
    +      * ``kubepods`` / ``containerd`` / ``crio`` markers in ``/proc/1/cgroup``.
    +      * the same markers in ``/proc/self/mountinfo`` (cgroup-v2 fallback).
    +
    +    Result is cached for the process lifetime.  Import-safe — no heavy deps.
    +
    +    See: NousResearch/hermes-agent#47111
         """
         global _container_detected
         if _container_detected is not None:
    @@ -476,10 +486,26 @@ def is_container() -> bool:
         if os.path.exists("/run/.containerenv"):
             _container_detected = True
             return True
    +    # Kubernetes always injects this into pod containers; absent on hosts.
    +    if os.environ.get("KUBERNETES_SERVICE_HOST"):
    +        _container_detected = True
    +        return True
    +    _CGROUP_MARKERS = ("docker", "podman", "/lxc/", "kubepods", "containerd", "crio")
         try:
             with open("/proc/1/cgroup", "r", encoding="utf-8") as f:
                 cgroup = f.read()
    -            if "docker" in cgroup or "podman" in cgroup or "/lxc/" in cgroup:
    +            if any(marker in cgroup for marker in _CGROUP_MARKERS):
    +                _container_detected = True
    +                return True
    +    except OSError:
    +        pass
    +    # cgroup v2: /proc/1/cgroup is just "0::/" with no marker. The container
    +    # runtime still shows up in the mount table (overlay rootfs, runtime mount
    +    # paths), so scan mountinfo as a last resort.
    +    try:
    +        with open("/proc/self/mountinfo", "r", encoding="utf-8") as f:
    +            mountinfo = f.read()
    +            if any(marker in mountinfo for marker in ("kubepods", "containerd", "crio")):
                     _container_detected = True
                     return True
         except OSError:

  • tests/test_hermes_constants.py

    @@ -139,13 +139,67 @@ def test_negative_case(self, monkeypatch, tmp_path):
             """Returns False on a regular Linux host."""
             import builtins
             self._reset_cache(monkeypatch)
    +        monkeypatch.delenv("KUBERNETES_SERVICE_HOST", raising=False)
             monkeypatch.setattr(os.path, "exists", lambda p: False)
             cgroup_file = tmp_path / "cgroup"
             cgroup_file.write_text("12:memory:/\n")
    +        mountinfo_file = tmp_path / "mountinfo"
    +        mountinfo_file.write_text("22 21 0:20 / /sys rw shared:7 - sysfs sysfs rw\n")
             _real_open = builtins.open
    -        monkeypatch.setattr("builtins.open", lambda p, *a, **kw: _real_open(str(cgroup_file), *a, **kw) if p == "/proc/1/cgroup" else _real_open(p, *a, **kw))
    +
    +        def _fake_open(p, *a, **kw):
    +            if p == "/proc/1/cgroup":
    +                return _real_open(str(cgroup_file), *a, **kw)
    +            if p == "/proc/self/mountinfo":
    +                return _real_open(str(mountinfo_file), *a, **kw)
    +            return _real_open(p, *a, **kw)
    +
    +        monkeypatch.setattr("builtins.open", _fake_open)
             assert is_container() is False
     
    +    def test_detects_kubernetes_env(self, monkeypatch):
    +        """KUBERNETES_SERVICE_HOST env var triggers detection (k8s/k3s pod)."""
    +        self._reset_cache(monkeypatch)
    +        monkeypatch.setattr(os.path, "exists", lambda p: False)
    +        monkeypatch.setenv("KUBERNETES_SERVICE_HOST", "10.43.0.1")
    +        assert is_container() is True
    +
    +    def test_detects_cgroup_kubepods(self, monkeypatch, tmp_path):
    +        """/proc/1/cgroup containing 'kubepods' triggers detection."""
    +        import builtins
    +        self._reset_cache(monkeypatch)
    +        monkeypatch.delenv("KUBERNETES_SERVICE_HOST", raising=False)
    +        monkeypatch.setattr(os.path, "exists", lambda p: False)
    +        cgroup_file = tmp_path / "cgroup"
    +        cgroup_file.write_text("12:memory:/kubepods/besteffort/podabc\n")
    +        _real_open = builtins.open
    +        monkeypatch.setattr("builtins.open", lambda p, *a, **kw: _real_open(str(cgroup_file), *a, **kw) if p == "/proc/1/cgroup" else _real_open(p, *a, **kw))
    +        assert is_container() is True
    +
    +    def test_detects_cgroup_v2_via_mountinfo(self, monkeypatch, tmp_path):
    +        """cgroup v2 (0::/ only) falls back to containerd marker in mountinfo."""
    +        import builtins
    +        self._reset_cache(monkeypatch)
    +        monkeypatch.delenv("KUBERNETES_SERVICE_HOST", raising=False)
    +        monkeypatch.setattr(os.path, "exists", lambda p: False)
    +        cgroup_file = tmp_path / "cgroup"
    +        cgroup_file.write_text("0::/\n")  # cgroup v2 — no runtime marker
    +        mountinfo_file = tmp_path / "mountinfo"
    +        mountinfo_file.write_text(
    +            "1234 1233 0:42 /containerd/.../rootfs / rw - overlay overlay rw\n"
    +        )
    +        _real_open = builtins.open
    +
    +        def _fake_open(p, *a, **kw):
    +            if p == "/proc/1/cgroup":
    +                return _real_open(str(cgroup_file), *a, **kw)
    +            if p == "/proc/self/mountinfo":
    +                return _real_open(str(mountinfo_file), *a, **kw)
    +            return _real_open(p, *a, **kw)
    +
    +        monkeypatch.setattr("builtins.open", _fake_open)
    +        assert is_container() is True
    +
         def test_caches_result(self, monkeypatch):
             """Second call uses cached value without re-probing."""
             monkeypatch.setattr(hermes_constants, "_container_detected", True)

• #105351 fix(agent): a host that merely runs containers is no longer classified as one (#58135, #48594, salvage #58141)

  merged to main

  files: hermes_constants.py, tests/test_hermes_constants.py

• #117591 fix(constants): scratch dir honours HERMES_HOME_MODE and managed-home permissions instead of forcing 0700 (#117347, salvage #117359)

  merged to main

  files: hermes_cli/config.py, hermes_constants.py, tests/hermes_cli/test_ensure_hermes_home_uid.py, tests/test_scratch_dir.py