Fail2ban action to build an apache 2 list of ip to block. See https://vaarlion.com/blog/how-to-use-fail2ban-when-there-is-a-proxy-in-the-way/

apache2-map.conf

# Fail2Ban configuration file
#
# Author: Vaarlion
#


[Definition]

# Option:  actionstart
# Notes.:  command executed on demand at the first ban (or at the start of Fail2Ban if actionstart_on_demand is set to false).
# Values:  CMD
#
actionstart = if [ ! -f <target> ]; then touch <target>; chgrp www-data <target>; chmod g+r <target>; printf %%b "<init>\n" <to_target>; fi;
              echo "%(debug)s started"

# Option:  actionflush
# Notes.:  command executed once to flush (clear) all IPS, by shutdown (resp. by stop of the jail or this action)
# Values:  CMD
#
actionflush = \> <target>; printf %%b "<init>\n" <to_target>;
              echo "%(debug)s clear all"

# Option:  actionstop
# Notes.:  command executed at the stop of jail (or at the end of Fail2Ban)
# Values:  CMD
#
actionstop = echo "%(debug)s stopped"

# Option:  actioncheck
# Notes.:  command executed once before each actionban command
# Values:  CMD
#
actioncheck = [ -f <target> ]

# 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 = if ! grep -q '<ip> -' <target>; then printf %%b "<ip> -    # fail2ban/$( date '+%%Y-%%m-%%d %%T' )\n" <to_target>; fi
            echo "%(debug)s banned <ip> (family: <family>)"

# 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 = if grep -q '<ip> -' <target>; then sed -i '/<ip> -/d' <target>; fi
              echo "%(debug)s unbanned <ip> (family: <family>)"


debug = [<name>] <actname> <target> --

[Init]

init = ### Block map for Apache2 ###

target = /etc/apache2/banned-hosts
to_target = >> <target>