ubuntu: start (upstart) second instance of mongodb - linux

Question

the standard upstart script that comes with mongodb works fine:
# Ubuntu upstart file at /etc/init/mongodb.conf
limit nofile 20000 20000
kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
pre-start script
mkdir -p /var/lib/mongodb/
mkdir -p /var/log/mongodb/
end script
start on runlevel [2345]
stop on runlevel [06]
script
ENABLE_MONGODB="yes"
if [ -f /etc/default/mongodb ]; then . /etc/default/mongodb; fi
if [ "x$ENABLE_MONGODB" = "xyes" ]; then exec start-stop-daemon --start --quiet --chuid mongodb --exec /usr/bin/mongod -- --config /etc/mongodb.conf; fi
end script
if i want to run a second instance of mongod i thought i just copy both /etc/mongodb.conf -> /etc/mongodb2.conf and /etc/init/mongodb.conf -> /etc/init/mongodb2.conf and change the std port in the first conf-file. then adjust the script above to start with the newly created /etc/mongodb2.conf.
i can then just say start mongodb2and the service starts ... but it is killed right after starting. what do i change, to get both processes up and running?
# Ubuntu upstart file at /etc/init/mongodb2.conf
limit nofile 20000 20000
kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
pre-start script
mkdir -p /var/lib/mongodb2/
mkdir -p /var/log/mongodb2/
end script
start on runlevel [2345]
stop on runlevel [06]
script
ENABLE_MONGODB="yes"
if [ -f /etc/default/mongodb ]; then . /etc/default/mongodb; fi
if [ "x$ENABLE_MONGODB" = "xyes" ]; then exec start-stop-daemon --start --quiet --chuid mongodb --exec /usr/bin/mongod -- --config /etc/mongodb2.conf; fi
end script

Answer 1

i couldn't get the "standard" upstart script to work (as described above), so i changed it like this:
# Ubuntu upstart file at /etc/init/mongodb.conf
limit nofile 20000 20000
kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
pre-start script
mkdir -p /var/lib/mongodb/
mkdir -p /var/log/mongodb/
end script
start on runlevel [2345]
stop on runlevel [06]
script
exec sudo -u mongodb /usr/bin/mongod --config /etc/mongodb.conf
end script
and if you want to run other instances of mongodb just copy the *.conf files and make the changes to /etc/mongodb2.conf and /etc/init/mongodb2.conf
# Ubuntu upstart file at /etc/init/mongodb2.conf
limit nofile 20000 20000
kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
pre-start script
mkdir -p /var/lib/mongodb2/
mkdir -p /var/log/mongodb2/
end script
start on runlevel [2345]
stop on runlevel [06]
script
exec sudo -u mongodb /usr/bin/mongod --config /etc/mongodb2.conf
end script
i think the only thing that is not working is restart mongodb - you have to stop and then start again ...

Answer 2

I know there's already an accepted solution but I think this one is more elegant.
The other way is to use start-stop-daemon's pid file creation. For example, I have 2 mongos running on the same server with 2 different upstart scripts, and the two magic lines are:
exec start-stop-daemon --make-pidfile --pidfile /var/run/mongodb-router.pid --start --startas /data/bin/mongos --chuid mongo -- --logappend --logpath /mnt/log/mongos.log --configdb mongo2-config01,mongo2-config02,mongo2-config03
exec start-stop-daemon --make-pidfile --pidfile /var/run/mongodb-routerrt.pid --start --startas /data/bin/mongos --chuid mongo -- --logappend --logpath /mnt/log/mongos-rt.log --configdb mongort-config01,mongort-config02,mongort-config03 --port 27027
Note that one has '--pidfile /var/run/mongodb-router.pid' and the other has '--pidfile /var/run/mongodb-routerrt.pid' and a different port.

Answer 3

Yeah I ran into this same issue today. The reason is that the default script uses the start-stop-daemon to start mongo, which is specifically designed to ensure that only one version of a process is running. You already figured out that one way to fix this is to not use start-stop-daemon and to start the binary yourself. That's the way I do it too but I'd be curious to hear if there's a better way.

Answer 4

This is how I do it.
2 instances of mongodb, with start-stop-daemon, on the same server
that are my start-stop-daemon configs
exec start-stop-daemon --make-pidfile --pidfile /var/lib/mongodb/db1.pid --start --quiet --chuid mongodb --name mongod1 --exec /usr/bin/mongod -- --config etc/mongodb1.conf
exec start-stop-daemon --make-pidfile --pidfile /var/lib/mongodb/db2.pid --start --quiet --chuid mongodb --name mongod2 --exec /usr/bin/mongod -- --config etc/mongodb2.conf
pay attention to the --name option. That did the trick for me

Answer 5

the two daemons cannot listen on the same tcp port, thus you have to change the --port parameter of mongod2 in order to listen to a different port.
the two daemons cannot share the same data dir, thus you have to change the --data-dir parameter of mongod2.

Answer 6

I find the below upstart works for me
# Ubuntu upstart file at /etc/init/mongodb.conf
description "manage mongodb instance"
start on runlevel [2345]
stop on runlevel [06]
limit nofile 20000 20000
kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
env MONGODB_USER=mongodb
env MONGODB_DATA=/var/lib/mongodb/
env MONGODB_LOG=/var/log/mongodb/
env MONGODB_PID=/var/run/mongodb.pid
pre-start script
if [ ! -d $MONGODB_DATA ]; then
mkdir -p $MONGODB_DATA
chown $MONGODB_USER:$MONGODB_USER $MONGODB_DATA
fi
if [ ! -d $MONGODB_LOG ]; then
mkdir -p $MONGODB_LOG
chown $MONGODB_USER:$MOGODB_USER $MONGODB_LOG
fi
end script
exec start-stop-daemon --start --pidfile $MONGODB_PID --chuid $MONGODB_USER:$MONGODB_USER --exec /usr/bin/mongod -- --config /etc/mongodb/mongodb.conf
pre-stop exec start-stop-daemon --signal QUIT --stop --quiet --pidfile $MONGODB_PID --chuid $MONGODB_USER:$MONGODB_USER --exec /usr/bin/mongod -- --config /etc/mongodb/mongodb.conf