From 11855b765ccd4a6586449084ce8823bcf06c487e Mon Sep 17 00:00:00 2001
From: Jeremy Fleischman <me@jfly.fyi>
Date: Fri, 22 May 2026 01:31:14 -0700
Subject: [PATCH 1/2] nixos/test-driver: null out self.pid when shutting down
 the container

Without this, we end up with `self.pid` set to the pid of a dead
process, and `self.process == None`. This causes us to blow [this
assert](https://github.com/jfly/nixpkgs/blob/dd51e81af9226ee80e6f0891f4649e12ea15dfd0/nixos/lib/test-driver/src/test_driver/machine/__init__.py#L1496)
in `NspawnMachine.release`.

It would probably be cleaner to just get rid of `self.pid`. It's
redundant given that we have `self.process`. I'll do that in a followup
commit.

This was discovered here:
https://github.com/NixOS/nixpkgs/pull/522886#discussion_r3285395646, and
will be protected against future regression by a test introduced in that
PR.
---
 nixos/lib/test-driver/src/test_driver/machine/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nixos/lib/test-driver/src/test_driver/machine/__init__.py b/nixos/lib/test-driver/src/test_driver/machine/__init__.py
index 3dc4f1f8d171..17f19f5d3068 100644
--- a/nixos/lib/test-driver/src/test_driver/machine/__init__.py
+++ b/nixos/lib/test-driver/src/test_driver/machine/__init__.py
@@ -1721,6 +1721,7 @@ class NspawnMachine(BaseMachine):
         with self.nested("waiting for the container to power off"):
             self.process.wait()
             self.process = None
+            self.pid = None
 
 
 class MachineDeprecationWrapper:

From b0ac1aa86405364fb2baa6bbec8952328424c34c Mon Sep 17 00:00:00 2001
From: Jeremy Fleischman <me@jfly.fyi>
Date: Fri, 22 May 2026 01:36:11 -0700
Subject: [PATCH 2/2] nixos/test-driver: remove redundant `self.pid` state from
 `NspawnMachine`

We can access it via `self.process`, and this avoids bugs where we
weren't keeping the 2 in sync.
---
 .../test-driver/src/test_driver/machine/__init__.py | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/nixos/lib/test-driver/src/test_driver/machine/__init__.py b/nixos/lib/test-driver/src/test_driver/machine/__init__.py
index 17f19f5d3068..790da705cf4f 100644
--- a/nixos/lib/test-driver/src/test_driver/machine/__init__.py
+++ b/nixos/lib/test-driver/src/test_driver/machine/__init__.py
@@ -1475,7 +1475,6 @@ class NspawnMachine(BaseMachine):
 
         self.start_command = start_command
         self.process = None
-        self.pid = None
 
         self.machine_sock_path = self.tmp_dir / f"{self.name}-nspawn.sock"
 
@@ -1486,14 +1485,13 @@ class NspawnMachine(BaseMachine):
         return f'ssh -o User=root -o ProxyCommand="{proxy_cmd}" bash'
 
     def release(self) -> None:
-        if self.pid is None:
+        if self.process is None:
             return
 
         if self.machine_sock:
             self.machine_sock.close()
 
-        self.logger.info(f"kill NspawnMachine (pid {self.pid})")
-        assert self.process is not None
+        self.logger.info(f"kill NspawnMachine (pid {self.process.pid})")
         self.process.terminate()
         # Wait for the wrapper to finish its context-manager cleanups
         # (veth/bridge/netns teardown) before returning, so the driver's
@@ -1502,7 +1500,7 @@ class NspawnMachine(BaseMachine):
             self.process.wait(timeout=30)
         except subprocess.TimeoutExpired:
             self.logger.error(
-                f"NspawnMachine {self.name} (pid {self.pid}) did not exit after SIGTERM; sending SIGKILL"
+                f"NspawnMachine {self.name} (pid {self.process.pid}) did not exit after SIGTERM; sending SIGKILL"
             )
             self.process.kill()
             self.process.wait()
@@ -1694,9 +1692,7 @@ class NspawnMachine(BaseMachine):
             stdout=subprocess.PIPE,
         )
 
-        self.pid = self.process.pid
-
-        self.log(f"systemd-nspawn running (pid {self.pid})")
+        self.log(f"systemd-nspawn running (pid {self.process.pid})")
 
         journal_thread = threading.Thread(target=self._stream_journal, daemon=True)
         journal_thread.start()
@@ -1721,7 +1717,6 @@ class NspawnMachine(BaseMachine):
         with self.nested("waiting for the container to power off"):
             self.process.wait()
             self.process = None
-            self.pid = None
 
 
 class MachineDeprecationWrapper: