add gluon-logging package

Allows reconfigurtion of remote syslog from within site.conf.

Conflicts with the gluon-web-logging package as user made changes
will be overwritten, because this package will reconfigure the syslog
destination on every upgrade.

Resolves #1845

docs/index.rst

@@ -65,6 +65,7 @@ Several Freifunk communities in Germany use Gluon as the foundation of their Fre
    package/gluon-ebtables-limit-arp
    package/gluon-ebtables-source-filter
    package/gluon-hoodselector
+   package/gluon-logging
    package/gluon-mesh-batman-adv
    package/gluon-mesh-wireless-sae
    package/gluon-radv-filterd

docs/package/gluon-logging.rst

+gluon-logging
+=============
+
+The *gluon-logging* package allows to configure a remote syslog server that
+will receive the systems log output that is also visible when calling ``logread``
+from a terminal.
+
+It supports both IPv4 and IPv6 endpoints over UDP and TCP.
+
+Note: The syslog mechanism is incapable of providing a complete log as network
+access is required to send out log messages and ``logd`` does not buffer and resend
+older log messages even though they might be available in ``logread``.
+
+This package conflicts with ``gluon-web-logging`` as it will overwrite the
+user-given syslog server on every upgrade.
+
+site.conf
+---------
+
+syslog.ip : required
+    - Destination address of the remote syslog server
+
+syslog.port : optional
+    - Destination port of the remote syslog server
+    - Defaults to 514
+
+syslog.proto : optional
+    - Protocol to transport syslog frames in, can be either ``tcp`` or ``udp``
+    - Defaults to UDP
+
+Example::
+
+  syslog = {
+    ip = "2001:db8::1",
+    port = 514,
+    proto = "udp",
+  },

package/gluon-logging/Makefile

+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=gluon-logging
+PKG_VERSION:=1
+
+include ../gluon.mk
+
+define Package/gluon-logging
+  TITLE:=Configure remote syslog from site.conf
+  DEPENDS:=+gluon-core
+  CONFLICTS:=gluon-web-logging
+endef
+
+$(eval $(call BuildPackageGluon,gluon-logging))
+

package/gluon-logging/check_site.lua

+need_string({'syslog', 'ip'}, true)
+need_number_range({'syslog', 'port'}, 1, 65535, false)
+need_one_of({'syslog', 'proto'}, {'tcp', 'udp'}, false)

package/gluon-logging/luasrc/lib/gluon/upgrade/040-syslog

+#!/usr/bin/lua
+local site = require('gluon.site')
+local uci = require('simple-uci').cursor()
+
+local system = uci:get_first('system', 'system')
+
+if not site.syslog.ip() then
+	uci:delete('system', system, 'log_remote')
+	uci:delete('system', system, 'log_ip')
+	uci:delete('system', system, 'log_port')
+	uci:delete('system', system, 'log_proto')
+else
+	uci:set('system', system, 'log_remote', 1)
+	uci:set('system', system, 'log_ip', site.syslog.ip())
+	uci:set('system', system, 'log_port', site.syslog.port(514))
+	uci:set('system', system, 'log_proto', site.syslog.proto('udp'))
+end
+
+uci:save('system')