From f05d8f00124b22bec2055581bdb7350a6665c1ba Mon Sep 17 00:00:00 2001
From: Michael <35783820+mib1185@users.noreply.github.com>
Date: Sat, 7 Sep 2024 00:45:49 +0200
Subject: [PATCH] Determine correct syslog level for ha core, supervisor and
 host messages (#6)

---
 syslog/journal2syslog.py | 62 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/syslog/journal2syslog.py b/syslog/journal2syslog.py
index 8a0df75..67f1ab6 100644
--- a/syslog/journal2syslog.py
+++ b/syslog/journal2syslog.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import logging
 import logging.handlers
 from os import environ
@@ -10,6 +12,42 @@
 SYSLOG_PROTO = str(environ["SYSLOG_PROTO"])
 HAOS_HOSTNAME = str(environ["HAOS_HOSTNAME"])
 
+LOGGING_NAME_TO_LEVEL_MAPPING = logging.getLevelNamesMapping()
+LOGGING_JOURNAL_PRIORITY_TO_LEVEL_MAPPING = [
+    logging.CRITICAL,  # 0 - emerg
+    logging.CRITICAL,  # 1 - alert
+    logging.CRITICAL,  # 2 - crit
+    logging.ERROR,  # 3 - err
+    logging.WARNING,  # 4 - warning
+    logging.INFO,  # 5 - notice
+    logging.INFO,  # 6 - info
+    logging.DEBUG,  # 7 - debug
+]
+LOGGING_DEFAULT_LEVEL = logging.INFO
+PATTERN_LOGLEVEL_HA = re.compile(
+    r"^\S+ \S+ (?P<level>INFO|WARNING|DEBUG|ERROR|CRITICAL) "
+)
+CONTAINER_PATTERN_MAPPING = {
+    "homeassistant": PATTERN_LOGLEVEL_HA,
+    "hassio_supervisor": PATTERN_LOGLEVEL_HA,
+}
+
+
+def parse_log_level(message: str, container_name: str) -> int:
+    """
+    Try to determine logging level from message
+    return: logging.<LEVELNAME> if determined
+    return: logging.NOTSET if not determined
+    """
+    if pattern := CONTAINER_PATTERN_MAPPING.get(container_name):
+        if (match := pattern.search(message)) is None:
+            return logging.NOTSET
+        return LOGGING_NAME_TO_LEVEL_MAPPING.get(
+            match.group("level").upper(), logging.NOTSET
+        )
+    return logging.NOTSET
+
+
 # start journal reader and seek to end of journal
 jr = journal.Reader(path="/var/log/journal")
 jr.this_boot()
@@ -37,13 +75,33 @@
 syslog_handler.setFormatter(formatter)
 logger.addHandler(syslog_handler)
 
+last_container_log_level: dict[str, int] = {}
+
 # wait for new messages in journal
 while True:
     change = jr.wait(timeout=None)
     for entry in jr:
         extra = {"prog": entry.get("SYSLOG_IDENTIFIER")}
-        if "CONTAINER_NAME" in entry:
+
+        # remove shell colors from container messages
+        if (container_name := entry.get("CONTAINER_NAME")) is not None:
             msg = re.sub(r"\x1b\[\d+m", "", entry.get("MESSAGE"))
         else:
             msg = entry.get("MESSAGE")
-        logger.log(level=entry.get("PRIORITY", logging.INFO), msg=msg, extra=extra)
+
+        # determine syslog level
+        if not container_name:
+            log_level = LOGGING_JOURNAL_PRIORITY_TO_LEVEL_MAPPING[
+                entry.get("PRIORITY", 6)
+            ]
+        elif container_name not in CONTAINER_PATTERN_MAPPING:
+            log_level = LOGGING_DEFAULT_LEVEL
+        elif log_level := parse_log_level(msg, container_name):
+            last_container_log_level[container_name] = log_level
+        else:  # use last log level if it could not be parsed (eq. for tracebacks)
+            log_level = last_container_log_level.get(
+                container_name, LOGGING_DEFAULT_LEVEL
+            )
+
+        # send syslog message
+        logger.log(level=log_level, msg=msg, extra=extra)