increase max number of ulimit open file and max user processes in Linux.

gistfile1.txt

1- Step :  open the sysctl.conf  and add this line  fs.file-max = 65536
 
vi /etc/sysctl.conf   add end of line 
fs.file-max=500000
 
save and exit.

2. Step : vi /etc/security/limits.conf  and add below the mentioned

*         soft    nproc       500000
*         hard    nproc       500000
*         hard    nofile      500000
*         soft    nofile      500000
root      hard    nofile      500000
root      soft    nofile      500000
jetadmin  hard    nofile      500000
jetadmin  soft    nofile      500000
nginx     hard    nofile      500000
nginx     soft    nofile      500000

and  vi /etc/security/limits.d/90-nproc.conf
 
*          soft     nproc          500000
*          hard     nproc          500000
*          soft     nofile         500000
*          hard     nofile         500000
 
save and exit 

3. Step - pam-limits
 
vi /etc/pam.d/common-session
 
Add following line at the end of the file:
 
session required pam_limits.so
 
save and exit 
 
4. Reboot ubuntu server

Nice reference can do this by appending to the end of the file too in scripted manner :)

#!/usr/bin/env bash
# References: https://gist.github.com/dotcomputercraft/0947eb7ed6b3b5cc14b6

echo "Increasing open files limit per user /etc/security/limits.conf"
cat >> /etc/security/limits.conf <<EOL
*         soft    nproc       500000
*         hard    nproc       500000
*         hard    nofile      500000
*         soft    nofile      500000
root      hard    nofile      500000
root      soft    nofile      500000
EOL

echo "Increasing open files limit per user /etc/security/limits.d/90-nproc.conf"
cat >> /etc/security/limits.d/90-nproc.conf <<EOL
*          soft     nproc          500000
*          hard     nproc          500000
*          soft     nofile         500000
*          hard     nofile         500000
EOL

echo "Raising System-Wide Limit open files /etc/sysctl.conf"
cat >> /etc/sysctl.conf <<EOL
fs.file-max = 2097152
EOL
sysctl -p

echo "Raising pam-limits /etc/pam.d/common-session"
cat >> /etc/pam.d/common-session <<EOL
session required pam_limits.so
EOL