dockerhostsync.sh

#!/bin/sh 

# filename: dockerhostsync.sh 
# example usage: sudo ./dockerhostsync.sh /etc/hosts

processfile=$1
tmpfile=${1}.tmp
backupfile=${1}.$(date "+%Y%m%d-%H%M%S").bak

# make a back-up
cp $processfile $backupfile

# loop all running docker containers
for service in `docker ps -q`; do
   # extract the metadata we need
   ipaddress=`docker inspect --format '{{ .NetworkSettings.Networks.nginx_easydev.IPAddress }}' $service`
   servicename=`docker inspect --format '{{ .Name }}' $service `

   # optional metadata
   hostname=`docker inspect --format '{{ .Config.Hostname }}' $service `
   domainname=`docker inspect --format '{{ .Config.Domainname }}' $service `
   fqdn=$hostname'.'$domainname
  
   # make sure service name and ipaddresses aren't empty
   if [[ -n $ipaddress ]] && [[ -n $servicename ]]; then

      # remove the leading character ('/')
      servicename=${servicename:1}

      # remove any lines with the service name from the process file, so we can add it again
      grep -v "$servicename" $processfile > $tmpfile

      # start constructing the line we'll be adding
      line=$ipaddress'\t'$servicename

      # add FQDN if we have it
      if [[ -n $domainname ]] && [[ -n $hostname ]]; then
         line=$line' '$fqdn
      fi

      # append line to file
      echo -e $line >> $tmpfile

      # finally replace the processfile with our temporary one
      mv $tmpfile $processfile
   fi
done