The Deploy system supports hooks that are started before or after deployment.
These hooks are executable files of any kind (e.g. shell scripts, Linux executable binaries).

~$ r3 deploy -h

usage: r3 deploy [-h] [-r ROLE] [--init-hook [INITHOOKDIR]] [--pre-hook [PREHOOKDIR]] [--post-hook [POSTHOOKDIR]] [--rev REV] [-n] [-m] [--sanity-check] [--list-roles | --list-sources] [-d] [-q]

optional arguments:
  -h, --help            show this help message and exit
  -r ROLE, --role ROLE  Server role to work on
  --init-hook [INITHOOKDIR]
                        Run initial hook scripts in default path "init-hook.d/" or given directory (optional)
  --pre-hook [PREHOOKDIR]
                        Run pre-deploy hook scripts in default path "pre-hook.d/" or given directory (optional)
  --post-hook [POSTHOOKDIR]
                        Run post-deploy hook scripts in default path "post-hook.d/" or given directory (optional)
  --rev REV             Specify tag/branch to clone (git deployment only!)
  -n, --skip-update     Skip update of source code (optional)
  -m, --skip-deploy     Skip distribution of source code (optional)
  --sanity-check        only check the sanity of all components
  --list-roles          List deployable roles and exit
  --list-sources        List source details and exit
  -d, --debug           Run in debug mode.
  -q, --quiet           Run in quiet mode (only errors are shown).

r3 deploy --pre-hook [directory]

#!/bin/bash
  
source /usr/local/lib/helper.sh
  
function usage() {
  echo "${SCRIPT} [-r role] [-p project] [-e environment] [-q|-d] [-h]"
  echo "  -h                  : print this help"
  echo "  -r role             : server role"
  echo "  -p project          : project name"
  echo "  -e environment      : environment name"
  exit 1
}
  
# iterate options
while getopts ':hr:p:e:' opt; do
  case "${opt}" in
    "r")
      role="${OPTARG}"
      ;;
    "p")
      project="${OPTARG}"
      ;;
    "e")
      environment="${OPTARG}"
      ;;
    "h")
      usage
      ;;
    ":")
      log error "Missing argument for option ${OPTARG}"
      usage
      ;;
    *)
      log error "Unknown option ${opt}"
      usage
      ;;
  esac
done
  
# print given project, environment and role
echo "${project}-${environment}-${role}"
  
# iterate all servers with given role in current project and run a command
for target in $(get-instances-by-role "${role}" --output text | awk -F ' ' '{print$2}' | grep -v 'ip'); do
  # connect to server and run cache.php
  if ssh "${target}" php /var/www/cache.php; then
    # if command run successfully on one server skip all other
    break
  fi
done
  
# do some more stuff