Format log timestamp like Prometheus

ui/temboardui/toolkit/log.py

@@ -1,6 +1,7 @@
 import datetime
 import logging
 import sys
+import time
 from logging.config import dictConfig
 from logging.handlers import SysLogHandler
 
@@ -132,17 +133,12 @@ def generate_logging_config(
     stderr_handler = "logging.StreamHandler"
     if sys.stderr.isatty():
         stderr_handler = __name__ + ".ColoredStreamHandler"
-        timestamp = "%(asctime)s "
         datefmt = "%H:%M:%S"
     else:
-        # strftime does not support milliseconds. Modifying datefmt disables Python hack
-        # to append milliseconds to timestamp. Thus, hardcode timezone in message format
-        # rather than datefmt.
-        timestamp = "%(asctime)s " + localoffset() + " "
         datefmt = None
 
     minimal_fmt = "%(levelname)s:  %(lastname)s: %(message)s"
-    verbose_fmt = timestamp + core + "[%(process)d] " + minimal_fmt
+    verbose_fmt = "%(asctime)s " + core + "[%(process)d] " + minimal_fmt
     syslog_fmt = core + "[%(process)d] %(levelname)s:  %(lastname)s: %(message)s"
 
     logging_config = {
@@ -157,7 +153,7 @@ def generate_logging_config(
             },
             "dated_syslog": {
                 "()": __name__ + ".MultilineFormatter",
-                "format": timestamp + syslog_fmt,
+                "format": "%(asctime)s " + syslog_fmt,
             },
             "syslog": {"()": __name__ + ".MultilineFormatter", "format": syslog_fmt},
             "systemd": {
@@ -193,3 +189,9 @@ def localoffset():
     hours = offset.seconds // 3600
     minutes = (offset.seconds // 60) % 60
     return "+%02d%02d" % (hours, minutes)
+
+
+# Make logging format consistent with Prometheus ts= format.
+logging.Formatter.converter = time.gmtime
+logging.Formatter.default_time_format = "%Y-%m-%dT%H:%M:%S"
+logging.Formatter.default_msec_format = "%s.%03dZ"  # Append UTC timezone.