config: Disable rsyslog and syslog forwarding

Helps: #664.

Currently, logs are written to disk twice, once by journald and once by rsyslog.
rsyslog may log to multiple locations depending on the type of the log. To
reduce disk I/O, disable rsyslog and rely solely on systemd journal.

Place the code in config module as there is no better place for it currently
without creating a new module. Can be sorted later.

The following files under /var/log/ are no longer populated on FreedomBox. They
will be rotated away over a few days. Use journalctl instead to view the
messages:

- syslog
- messages*
- auth.log*
- debug*
- daemon.log
- kern.log
- lpr.log
- mail.log
- mail.info
- mail.warn
- mail.err
- user.log

Tests performed:

- On a machine with rsyslog running, run ./setup.py install and start FreedomBox
service. This triggers the config app's setup. rsyslog is disabled and masked.
systemd-journald is restarted.

- Even when rsyslog is unmaked and enabled manually, systemd journald does not
forward message to syslog anymore.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Veiko Aasa <veiko17@disroot.org>

plinth/modules/config/__init__.py

@@ -12,15 +12,17 @@ from django.utils.translation import ugettext_lazy as _
 from plinth import actions
 from plinth import app as app_module
 from plinth import frontpage, menu
-from plinth.modules.apache import (user_of_uws_url, uws_url_of_user,
-                                   get_users_with_website)
+from plinth.modules.apache import (get_users_with_website, user_of_uws_url,
+                                   uws_url_of_user)
 from plinth.modules.names.components import DomainType
 from plinth.signals import domain_added
 
-version = 2
+version = 3
 
 is_essential = True
 
+managed_services = ['systemd-journald', 'rsyslog']
+
 _description = [
     _('Here you can set some general configuration options '
       'like hostname, domain name, webserver home page etc.')
@@ -161,7 +163,7 @@ def change_home_page(shortcut_id):
     """
     url = _home_page_scid2url(shortcut_id)
     if url is None:
-        url = '/plinth/'  	# fall back to default url if scid is unknown.
+        url = '/plinth/'  # fall back to default url if scid is unknown.
 
     # URL may be a reverse_lazy() proxy
     actions.superuser_run('config', ['set-home-page', str(url)])
@@ -183,6 +185,16 @@ def setup(helper, old_version=None):
     """Install and configure the module."""
     _migrate_home_page_config()
 
+    # systemd-journald is socket activated, it may not be running and it does
+    # not support reload.
+    actions.superuser_run('service', ['try-restart', 'systemd-journald'])
+    # rsyslog when enabled, is activated by syslog.socket (shipped by systemd).
+    # See: https://www.freedesktop.org/wiki/Software/systemd/syslog/ .
+    actions.superuser_run('service', ['disable', 'rsyslog'])
+    # Ensure that rsyslog is not started by something else as it is installed
+    # by default on Debian systems.
+    actions.superuser_run('service', ['mask', 'rsyslog'])
+
 
 def _migrate_home_page_config():
     """Move the home page configuration to an external file."""

plinth/modules/config/data/usr/lib/systemd/journald.conf.d/freedombox.conf

@@ -0,0 +1,12 @@
+[Journal]
+# Upstream systemd project disables forwarding to syslog by default as it is
+# only needed by syslog daemons that don't get their feed from systemd journal.
+# See:
+# https://www.freedesktop.org/software/systemd/man/journald.conf.html#ForwardToSyslog=
+# . Debian re-enables this by default due to support lacking in some syslog
+# daemons in its repository. See:
+# https://salsa.debian.org/systemd-team/systemd/-/blob/c39ab3efdc9c1b69f333c112112a68fb712cee27/debian/patches/debian/Re-enable-journal-forwarding-to-syslog.patch
+# . In FreedomBox, rsyslog and other syslog daemons are not necessary and are
+# burden on disk I/O. All the necessary log data can be obtained from systemd
+# journal. Disable forwarding to syslog.
+ForwardToSyslog=no