Hi all,
This is the text I have added to the Wt 3.1.11 Debian packages. Please
comment.
--8<------------
HOW TO START/STOP WT WEBAPPS
Let's start with some facts:
- the Wt webapp needs to be launched somehow
- in the general case (production), it will be started automatically
- wtfcgi requires a /var/run/wt directory, wthttp does not
Case 1: wthttp webapp
=====================
There are three subcases here:
1.1 wthttp webapp started by init/upstart
-----------------------------------------
Create an init script or upstart job to start the webapp.
You do not need to create /var/run/wt
It is recommended that the init script or upstart job starts the
webapp as the www-data user and group.
1.2 wthttp webapp started by inetd
----------------------------------
Inetd starts services on demand.
You do not need to write any script.
When the requests are spaced enough in time, no active instance of your
webapp
will be running, therefore there is a small loading delay. You should take
this into account.
The delay is smaller for statically-compiled webapps, because there is no
need
to look for dynamic libraries and resolve symbols on load.
1.3 HTTP server forwarding to wthttp webapp
-------------------------------------------
This is like case 2.1
Case 2: wtfcgi webapp
=====================
There are two subcases here, although the second one is very uncommon
2.1 wtfcgi webapp started by a web server
-----------------------------------------
You will need to write an init script. See below for the explanation.
This init script must create /var/run/wt and set the proper permissions.
The recommended settings are making www-data owner of that directory (both
user and group).
Make sure /var/run/wt is ready when the web server is started, otherwise
there might be a race condition (the webserver receives a request and starts
your wtfcgi webapp but /var/run/wt does not exist yet, therefore wtfcgi
fails).
To avoid that:
- If using an init script, it should be run before or at the same time as
the
web server. For instance, Apache 2 is S91.
- If using an upstart job, set the dependency on your web server
Why is an init script required for creating /var/run/wt? Because only root
can
write to /var/run
But I can create /var/run/wt and it will be there forever! No, it will not.
The Filesystem Hierarchy Standard mandates that /var/run be entirely cleaned
on boot.
2.2 wtfcgi webapp started by cgi-fcgi
-------------------------------------
Unless your hosting server has a very strange policy, this scenario should
never happen in production environments.
The cgi-fcgi tool makes possible to start FastCGI applications from the
command line. See the mention of the 'cgi-fcgi' tool in
http://www.fastcgi.com/mod_fastcgi/docs/mod_fastcgi.html#FastCgiExternalServer
This case is almost the same as 2.1. The only difference is you will need to
make /var/run/wt available before cgi-fcgi (that would be in turn run by
some
other script your host provider mandates) starts the wtfcgi webapp.
APPENDIX A Init script sample for wthttp webapp (case 1.1)
#!/bin/sh
### BEGIN INIT INFO
# Provides: mywebapp
# Required-Start: $remote_fs $syslog $network $named $time
# Required-Stop: $remote_fs $syslog $network
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start mywebapp at boot time
# Description: Enable service provided by mywebapp.
### END INIT INFO
# /etc/init.d/mywebapp
#
# Written by Pau Garcia i Quiles <pgqui...@elpauer.org>
set -e
if [ ! -f /etc/elpauer/mywebapp.conf ] ; then
exit 0
fi
DAEMON=/opt/elpauer/mywebapp/bin/mywebapp.wt
NAME=mywebapp.wt
test -x $DAEMON || exit 0
. /lib/lsb/init-functions
case "$1" in
start)
log_begin_msg "Starting MyWebApp server: $NAME"
[ -d /var/run/mywebapp ] || mkdir -p /var/run/mywebapp
start-stop-daemon --background -m --pidfile
/var/run/mywebapp/mywebapp.pid --exec $DAEMON -c www-data:www-data --start
-- --docroot /opt/elpauer/mywebapp/share --http-addr 0.0.0.0 --http-port 80
&& log_end_msg 0 || log_end_msg 1
;;
stop)
log_begin_msg "Stopping MyWebApp server: $NAME"
start-stop-daemon --stop --pidfile /var/run/mywebapp/mywebapp.pid
--oknodo --exec $DAEMON && log_end_msg 0 || log_end_msg 1
rm -f /var/run/mywebapp/mywebapp.pid
;;
restart)
$0 stop
$0 start
;;
reload|force-reload)
log_begin_msg "Reloading $NAME configuration files"
start-stop-daemon --stop --pidfile/var/run/mywebapp/mywebapp.pid
--signal 1 --exec $DAEMON && log_end_msg 0 || log_end_msg 1
;;
*)
log_success_msg "Usage: /etc/init.d/$NAME {start|stop|restart|reload}"
exit 1
;;
esac
exit 0
APPENDIX B Init script sample for wtfcgi webapp
#!/bin/sh
### BEGIN INIT INFO
# Provides: mywebapp
# Required-Start: $remote_fs $syslog $network $named $time
# Required-Stop: $remote_fs $syslog $network
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# X-Start-Before: apache2
# Short-Description: Start mywebapp at boot time
# Description: Enable service provided by mywebapp.
### END INIT INFO
# /etc/init.d/mywebapp
#
# Written by Pau Garcia i Quiles <pgqui...@elpauer.org>
set -e
if [ ! -f /etc/elpauer/mywebapp.conf ] ; then
exit 0
fi
DAEMON=/opt/elpauer/mywebapp/bin/mywebapp.fcgi
NAME=mywebapp.fcgi
test -x $DAEMON || exit 0
. /lib/lsb/init-functions
case "$1" in
start)
log_begin_msg "Creating /var/run/wt required by MyWebApp: $NAME"
[ -d /var/run/wt ] || mkdir -p /var/run/wt
;;
stop)
log_begin_msg "Removing /var/run/wt required by MyWebApp: $NAME"
;;
restart)
$0 stop
$0 start
;;
*)
log_success_msg "Usage: /etc/init.d/$NAME {start|stop|restart}"
exit 1
;;
esac
exit 0
APPENDIX C Upstart job
No sample provided, see
http://upstart.ubuntu.com/cookbook/#run-a-job-as-a-different-user
--8<------------
--
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)
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