Keep Steam Runtime's logger out of the journal

Steam's srt-logger runs inside steam-backlog-enforcer.service's cgroup
and mirrors Steam's console into journald on its own — the DEVNULL
stderr the spawn already uses does not reach it, and the env carried
SRT_LOG_TO_JOURNAL=0, which is not the variable it reads. One boot on
2026-09-12 wrote 481k "joystick FFB effect status" lines (99% of the
journal) and evicted two weeks of history from a 300M journal, along
with the evidence for that night's curfew failure.

- desktop_env_args(): SRT_LOGGER_USE_JOURNAL=0, the variable srt-logger
  actually honours. Steam keeps its own logs/console-linux.txt.
- Unit: LogFilterPatterns for the two known flood patterns plus a
  per-unit rate limit, so a future Steam that ignores the variable still
  cannot take the journal with it.

The unit file is deployed and daemon-reloaded; the running service is
not restarted, because Steam is its child and a restart would kill a
live game. The env fix takes effect on the next enforcer start.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mLnUeoJ3mUwGRTowTUH6d

steam-backlog-enforcer.service

@@ -16,6 +16,15 @@ Environment=STEAM_ENFORCER_DESKTOP_USER=__DESKTOP_USER__
 Environment=DISPLAY=:0
 # Hardening: enforcer must not be easily killed.
 OOMScoreAdjust=-900
+# Journal backstop. Steam's srt-logger runs in this unit's cgroup and mirrors
+# Steam's console into journald; 2026-09-12 it wrote 481k "joystick FFB"
+# lines in one boot (99% of the journal) and evicted two weeks of history.
+# SRT_LOGGER_USE_JOURNAL=0 in the spawn env is the fix at source; these two
+# make sure a future Steam that ignores it still cannot flood the journal.
+LogFilterPatterns=~Failed to get joystick[0-9]+ FFB effect status
+LogFilterPatterns=~FFBInterface
+LogRateLimitIntervalSec=1min
+LogRateLimitBurst=2000
 #
 # DO NOT ADD PrivateMounts=, PrivateTmp=, ProtectSystem= OR ProtectHome= HERE.
 # The daily gaming budget enforces its cutoff by bind-mounting a refusal stub

steam_backlog_enforcer/_desktop_env.py

@@ -70,6 +70,13 @@ def desktop_env_args(user: str, uid: int) -> list[str]:
         f"XAUTHORITY={xauth}",
         f"DBUS_SESSION_BUS_ADDRESS={dbus_addr}",
         f"XDG_RUNTIME_DIR={runtime_dir}",
+        # Steam Runtime's srt-logger opts INTO the journal when it finds one
+        # (it inherits this unit's JOURNAL_STREAM), regardless of the DEVNULL
+        # stderr the spawn already uses. That wrote 481k "joystick FFB" lines
+        # in one boot and evicted two weeks of history from a 300M journal.
+        # Steam still keeps its own logs/console-linux.txt; this only stops
+        # the copy into journald.
+        "SRT_LOGGER_USE_JOURNAL=0",
     ]
 
 

steam_backlog_enforcer/tests/test_desktop_env.py

@@ -55,6 +55,16 @@ class TestDesktopEnvArgs:
             args = desktop_env_args("bob", 1000)
         assert _env_value(args, "XDG_RUNTIME_DIR") == "/run/user/1000"
 
+    def test_steam_runtime_logger_kept_out_of_the_journal(self) -> None:
+        """srt-logger must be told not to mirror Steam's console into journald.
+
+        It inherits the service's JOURNAL_STREAM and opts in on its own; one
+        boot's worth of joystick FFB errors (481k lines) evicted two weeks of
+        journal history and the evidence for a curfew failure with it.
+        """
+        args = desktop_env_args("bob", 1000)
+        assert _env_value(args, "SRT_LOGGER_USE_JOURNAL") == "0"
+
     def test_dbus_address_defaults_to_uid_path(self) -> None:
         """DBUS falls back to the uid-derived socket when unset."""
         env_copy = os.environ.copy()