GCP Fix Hosts

#!/bin/bash
 
# VARIABLES
FILE='/etc/hosts'
 
#BACKUP /etc/hosts before changes
cp -ipHR $FILE $FILE_$(date +%Y-%m-%d_%H-%M-%S)
 
# GET IP ADDRESS
IP=$(/sbin/ifconfig | grep 'inet' | grep -v 'inet6' | grep -v '127.0' | cut -d: -f2 | awk '{print $2}' | head -1)
 
# GET HOSTNAME
HN=$(/bin/hostname)
 
# GET PROJECT ID
echo "169.254.169.254 metadata.google.internal  # Added by Google" >> $FILE
PR=$(curl -f -s http://metadata.google.internal/computeMetadata/v1/project/project-id -H "Metadata-Flavor: Google")
 
# ADD HOSTNAME ENTRY TO /etc/hosts
STRING="$IP $HN.mydomain.com"
 
if grep -q "$STRING" "$FILE"
then
  echo "Valid host entry."
else
  echo "Adding host entry."
  echo $STRING $HN >> $FILE
fi
 
# DELETE GOOGLE ENTRIES.
sed -i '/# Added by Google/d' $FILE
 
# ADD BACK GOOGLE ENTRIES.
echo $IP $HN".c."$PR".internal" $HN"  # Added by Google" >> $FILE
echo "169.254.169.254 metadata.google.internal  # Added by Google" >> $FILE
 
# SET PERMISSIONS.
chmod 644 $FILE
 
# DISPLAY /etc/hosts
cat $FILE

127.0.0.1       localhost
::1             localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters
 
10.128.0.30 test.mydomain.com test
10.128.0.30 test.c.project-id.internal test  # Added by Google
169.254.169.254 metadata.google.internal  # Added by Google