One thing that is normally looked over at first when configuring a VM for a service like RabbitMQ or SaltStack is the max open files limits. These services have a lot of clients with consistent established connections. This creates a high amount of open sockets which means you got to make sure the max open files limit is sufficient for the services processes to operate.
If you want to see what your services process limits are you can cat out the /proc/pid/limits file.
Make sure you know what your VMs maximum number of open files is so you don’t over allocate the open files limit. If you do and those services hit that max you might not have enough File Descriptors to create a pam session to login to VM. Which could be bad ;).
cat /proc/sys/fs/file-max
379261Now create limits.d configuration file for this services user, in this case the rabbitmq user.
cat /etc/limits.d/rabbmitmq.conf
rabbitmq soft nofile 150000
rabbitmq hard nofile 150000Restart the rabbitmq process…
service rabbitmq-server restartMake sure the new limits are in place…
cat /proc/7654/limits
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size 0 unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 29818 29818 processes
Max open files 150000 150000 files <<<<<<<<<<---------
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 29818 29818 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us