Simplify LNT's logging story

deployment/README.md

@@ -48,9 +48,6 @@ docker logs webserver
 docker logs dbserver # usually less interesting
 ```
 
-Finally, the application-level logs produced by LNT (which are usually the most interesting)
-can be inspected under `/var/log/lnt`.
-
 The database is stored in an independent EBS storage that gets attached and detached
 to/from the EC2 instance when it is created/destroyed, but the EBS storage has its own
 independent life cycle (because we want the data to outlive any specific EC2 instance).

deployment/ec2-volume-mapping.yaml

@@ -12,13 +12,6 @@ volumes:
       type: none
       device: /var/lib/lnt
 
-  logs:
-    driver: local
-    driver_opts:
-      o: bind
-      type: none
-      device: /var/log/lnt
-
   database:
     driver: local
     driver_opts:

deployment/on-ec2-boot.sh

@@ -21,7 +21,6 @@ fi
 echo "Creating necessary filesystem hierarchy on the persistent volume"
 mkdir -p /mnt/lnt-persistent-state/var/lib/lnt
 mkdir -p /mnt/lnt-persistent-state/var/lib/postgresql
-mkdir -p /var/log/lnt # logs are not persisted
 
 echo "Linking locations inside the persistent volume to the expected locations on the instance"
 if [[ ! -e "/var/lib/lnt" ]]; then

docker/compose.yaml

@@ -56,7 +56,6 @@ services:
         condition: on-failure
     volumes:
       - instance:/var/lib/lnt
-      - logs:/var/log/lnt
     # Only expose this port to the internal Docker network, but not to
     # the outside world.
     expose:
@@ -100,7 +99,6 @@ services:
 
 volumes:
   instance:
-  logs:
   database:
 
 secrets:

docker/docker-entrypoint.sh

@@ -28,6 +28,5 @@ exec gunicorn lnt_wsgi:application                      \
     --workers 8                                         \
     --timeout 300                                       \
     --name lnt_server                                   \
-    --log-file /var/log/lnt/lnt.log                     \
-    --access-logfile /var/log/lnt/gunicorn_access.log   \
+    --access-logfile -                                  \
     --max-requests 250000

docker/lnt.dockerfile

@@ -22,9 +22,6 @@
 #   /var/lib/lnt
 #     The actual LNT instance data (schema files, configuration files, etc).
 #
-#   /var/log/lnt
-#     Log files for the instance.
-#
 
 FROM python:3.10-alpine AS builder
 
@@ -50,8 +47,8 @@ RUN apk update && apk add --no-cache libpq
 
 COPY --from=builder /root/.local /root/.local
 
-# Prepare volumes that will be used by the server
-VOLUME /var/lib/lnt /var/log/lnt
+# Prepare volume that will be used by the server
+VOLUME /var/lib/lnt
 
 # Set up the actual entrypoint that gets run when the container starts.
 COPY docker/docker-entrypoint.sh docker/lnt-wait-db /usr/local/bin/

lnt/lnttool/runserver.py

@@ -41,7 +41,7 @@ def action_runserver(instance_path, hostname, port, reloader, debugger,
 
     init_logger(logging.INFO, show_sql=show_sql)
 
-    app = lnt.server.ui.app.App.create_standalone(instance_path,)
+    app = lnt.server.ui.app.App.create_standalone(instance_path)
     if debugger:
         app.debug = True
     if profiler:

lnt/server/ui/app.py

@@ -1,8 +1,6 @@
 import importlib.metadata
 import io
 import logging
-import logging.handlers
-import sys
 import time
 import traceback
 from logging import Formatter
@@ -32,10 +30,6 @@
 from lnt.util import logger
 
 
-# The default name of the log file.
-LOG_FILENAME = "lnt.log"
-
-
 class RootSlashPatchMiddleware(object):
     def __init__(self, app):
         self.app = app
@@ -190,24 +184,24 @@ def internal_server_error(e):
         return app
 
     @staticmethod
-    def create_standalone(config_path, log_file=None):
+    def create_standalone(config_path):
         """
         Create an instance of a lnt Flask application from a config file.
 
         :param config_path: path to lnt config (directory or config file).
-
-        :param log_file: instead of setting up logging, use this log file.
-        when running in a multiprocess server like gunicorn, you need to use
-        gunicorn's logging instead (since it is multiprocess safe. In this case
-        LNT will print to to stderr and it can be collected by gunicorn. The
-        LNT logs page will show this unified log page.
-
         :return: a LNT Flask App, ready to be loaded into a wsgi server.
-
         """
         instance = lnt.server.instance.Instance.frompath(config_path)
         app = App.create_with_instance(instance)
-        app.start_file_logging(log_file)
+
+        # Always log to stderr. In production, the webserver is generally run
+        # inside a Docker container where logging to stderr is the de facto
+        # standard.
+        handler = logging.StreamHandler()
+        handler.setLevel(logging.DEBUG)
+        handler.setFormatter(Formatter('%(levelname)s: %(message)s [in %(filename)s:%(lineno)d %(asctime)s]'))
+        app.logger.addHandler(handler)
+
         return app
 
     def __init__(self, name):
@@ -241,42 +235,6 @@ def load_config(self, instance):
 
         lnt.server.db.rules_manager.register_hooks()
 
-    def start_file_logging(self, log_file_name):
-        """Start server production logging.  At this point flask already logs
-        to stderr, so just log to a file as well.
-
-        """
-        # Always Print to screen.
-        ch = logging.StreamHandler()
-        ch.setLevel(logging.DEBUG)
-        ch.setFormatter(Formatter('%(levelname)s: %(message)s '
-                                  '[in %(filename)s:%(lineno)d %(asctime)s]'))
-        self.logger.addHandler(ch)
-
-        # When running in a server config, use the server to setup the log
-        # file. If there is more than one process running, this will not work
-        # well.
-        if not log_file_name:
-            self.config['log_file_name'] = LOG_FILENAME
-            try:
-                rotating = logging.handlers.RotatingFileHandler(
-                    LOG_FILENAME, maxBytes=1048576, backupCount=5)
-                rotating.setFormatter(Formatter(
-                    '%(asctime)s %(levelname)s: %(message)s '
-                    '[in %(filename)s:%(lineno)d]'
-                ))
-                rotating.setLevel(logging.DEBUG)
-                self.logger.addHandler(rotating)
-            except (OSError, IOError) as e:
-                print("Error making log file",
-                      LOG_FILENAME, str(e), file=sys.stderr)
-                print("Will not log to file.", file=sys.stderr)
-            else:
-                self.logger.info("Started file logging.")
-                print("Logging to :", LOG_FILENAME)
-        else:
-            self.config['log_file_name'] = log_file_name
-
 
 def create_jinja_environment(env=None):
     """

lnt/server/ui/templates/layout.html

@@ -205,7 +205,6 @@
                     <li class="dropdown">
                         <a href="#" class="dropdown-toggle" data-toggle="dropdown">System<b class="caret"></b></a>
                         <ul class="dropdown-menu">
-                          <li><a href="{{ url_for('.log') }}">Logs</a></li>
                           <li><a href="{{ url_for('.rules') }}">Rules</a></li>
                           <li><a href="{{ url_for('.profile_admin') }}">Profiles</a></li>
                           <li><a href="{{ url_for('.static', filename='docs/index.html') }}">Documentation</a></li>

lnt/server/ui/views.py

@@ -1797,13 +1797,6 @@ def rules():
     return render_template("rules.html", rules=discovered_rules)
 
 
-@frontend.route('/log')
-def log():
-    with open(current_app.config['log_file_name'], 'r') as f:
-        log_lines = f.readlines()
-    return render_template("log.html", log_lines=log_lines)
-
-
 @frontend.route('/debug')
 def debug():
     assert not current_app.debug

tests/server/ui/V4Pages.py

@@ -652,7 +652,6 @@ def main():
     check_html(client, '/db_default/summary_report')
 
     check_html(client, '/rules')
-    check_html(client, '/log')
     resp = check_code(client, '/__health')
     assert resp.get_data(as_text=True) == "Ok"
     resp = check_code(client, '/ping')