Fail2Ban using ngx_http_access_module.

nginx-ngx_http_access.conf

# Fail2Ban configuration file
#
# Author: Turan Asikoglu
#
#

[Definition]

# Option:  actionstart
# Notes.:  command executed once at the start of Fail2Ban.
# Values:  CMD
#
actionstart = touch <file>

# Option:  actionstop
# Notes.:  command executed once at the end of Fail2Ban
# Values:  CMD
#
actionstop = touch <file>

# Option:  actioncheck
# Notes.:  command executed once before each actionban command
# Values:  CMD
#
actioncheck = 

# Option:  actionban
# Notes.:  command executed when banning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    See jail.conf(5) man page
# Values:  CMD
#
actionban = printf %%b "deny <ip>;\n" >> <file>
            nginx -s reload

# Option:  actionunban
# Notes.:  command executed when unbanning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    See jail.conf(5) man page
# Values:  CMD
#
actionunban = echo "/deny <ip>;$/<br>d<br>w<br>q" | ed <file>
              nginx -s reload

[Init]

# Option:  file
# Notes.:  fail2ban-blacklist.conf file path.
# Values:  STR  Default:  /etc/nginx/fail2ban-blacklist.conf
#
file = /etc/nginx/fail2ban-blacklist.conf