gcp-assign-vip.sh

#!/bin/bash
internal=false
external=false
while getopts ":i:e:" opt; do
    case "$opt" in
    i)  internal_vip=$OPTARG
        internal=true
        ;;
    e)  external_vip=$OPTARG
        external=true
    esac
done

if $internal; then
  echo 'Startup....'
else
  echo "Usage: $0 -i INTERNAL_VIP_NAME [-e EXTERNAL_VIP_NAME]" &>> /var/log/gcp-failoverd/startup.log
  exit 1
fi

mkdir -p /var/log/gcp-failoverd
internal_status=true
external_status=true
while $internal_status || $external_status; do
  ZONE=`gcloud compute instances list --filter="name=$(hostname)"| grep $(hostname) | awk '{ print $2 }'`
  if $internal && $internal_status; then
    INTERNAL_IP=`gcloud compute addresses list --filter="name=$internal_vip"| grep $internal_vip | awk '{ print $2 }'`
    INTERNAL_IP_STATUS=`gcloud compute addresses list --filter="name=$internal_vip"| grep $internal_vip | awk '{ print $NF }'`
    if [[ $INTERNAL_IP_STATUS == "IN_USE" ]];
    then
      INTERNAL_INSTANCE_REGION=$(gcloud compute addresses list --filter="name=${internal_vip}"|grep ${internal_vip}|awk '{print $(NF-2)}')
      INTERNAL_INSTANCE_NAME=$(gcloud compute addresses describe ${internal_vip} --region=${INTERNAL_INSTANCE_REGION} --format='get(users[0])'|awk -F'/' '{print $NF}')
      INTERNAL_INSTANCE_ZONE=$(gcloud compute instances list --filter="name=${INTERNAL_INSTANCE_NAME}"|grep ${INTERNAL_INSTANCE_NAME}|awk '{print $2}')
      INTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${INTERNAL_INSTANCE_ZONE} $INTERNAL_INSTANCE_NAME --format='get(status)')
      #First check if already assigned to it
      if [[ $INTERNAL_INSTANCE_NAME == $(hostname) ]];
      then
        echo "$INTERNAL_IP is already assigned to $INTERNAL_INSTANCE_NAME. Taking no action..." &>> /var/log/gcp-failoverd/default.log
        internal_status=false
        continue
      fi
      #Wait for the instance to stop before taking over
      while [[ $INTERNAL_INSTANCE_STATUS == "STOPPING" ]]; do
        INTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${INTERNAL_INSTANCE_ZONE} $INTERNAL_INSTANCE_NAME --format='get(status)')
        echo "The instance $INTERNAL_INSTANCE_NAME has a status of $INTERNAL_INSTANCE_STATUS" &>> /var/log/gcp-failoverd/default.log
        sleep 2
      done
      echo "Sleeping for 5 secs...."  &>> /var/log/gcp-failoverd/default.log
      sleep 5
      INTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${INTERNAL_INSTANCE_ZONE} $INTERNAL_INSTANCE_NAME --format='get(status)')
      if [[ $INTERNAL_INSTANCE_STATUS == "TERMINATED" ]];
      then
        echo "The instance $INTERNAL_INSTANCE_NAME has a status of $INTERNAL_INSTANCE_STATUS" &>> /var/log/gcp-failoverd/default.log
        #Update the alias from the terminated instance to null
        until gcloud compute instances network-interfaces update $INTERNAL_INSTANCE_NAME --zone $INTERNAL_INSTANCE_ZONE --aliases "" &>> /var/log/gcp-failoverd/default.log; do
          echo "Trying to update the alias from $INTERNAL_INSTANCE_NAME to null" &>> /var/log/gcp-failoverd/default.log
          sleep 2
        done
      fi
    fi
    # Assign IP aliases to me because now I am the MASTER!
    until gcloud compute instances network-interfaces update $(hostname) --zone $ZONE --aliases "${INTERNAL_IP}/32" &>> /var/log/gcp-failoverd/default.log; do
      echo "Trying to assign IP aliases to me because now I am the MASTER!" &>> /var/log/gcp-failoverd/default.log
      sleep 2
    done
    echo "I became the MASTER of ${INTERNAL_IP} at: $(date)" >> /var/log/gcp-failoverd/default.log
    internal_status=false
  else
    internal_status=false
  fi

  if $external; then
    EXTERNAL_IP=`gcloud compute addresses list --filter="name=$external_vip"| grep $external_vip | awk '{ print $2 }'`
    EXTERNAL_IP_STATUS=`gcloud compute addresses list --filter="name=$external_vip"| grep $external_vip | awk '{ print $NF }'`
    if [[ $EXTERNAL_IP_STATUS == "IN_USE" ]];
    then
      EXTERNAL_INSTANCE_REGION=$(gcloud compute addresses list --filter="name=${external_vip}"|grep ${external_vip}|awk '{print $(NF-1)}')
      EXTERNAL_INSTANCE_NAME=$(gcloud compute addresses describe ${external_vip} --region=${EXTERNAL_INSTANCE_REGION} --format='get(users[0])'|awk -F'/' '{print $NF}')
      EXTERNAL_INSTANCE_ZONE=$(gcloud compute instances list --filter="name=${EXTERNAL_INSTANCE_NAME}"|grep ${EXTERNAL_INSTANCE_NAME}|awk '{print $2}')
      EXTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${EXTERNAL_INSTANCE_ZONE} $EXTERNAL_INSTANCE_NAME --format='get(status)')
      EXTERNAL_ACCESS_CONFIG=$(gcloud compute instances describe --zone=${EXTERNAL_INSTANCE_ZONE} $EXTERNAL_INSTANCE_NAME --format='get(networkInterfaces[0].accessConfigs[0].name)')
      #First check if already assigned to it
      if [[ $EXTERNAL_INSTANCE_NAME == $(hostname) ]];
      then
        echo "$EXTERNAL_IP is already assigned to $EXTERNAL_INSTANCE_NAME. Taking no action..." &>> /var/log/gcp-failoverd/default.log
        external_status=false
        continue
      fi
      #Wait for the instance to stop before taking over
      while [[ $EXTERNAL_INSTANCE_STATUS == "STOPPING" ]]; do
        EXTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${EXTERNAL_INSTANCE_ZONE} $EXTERNAL_INSTANCE_NAME --format='get(status)')
        echo "The instance $EXTERNAL_INSTANCE_NAME has a status of $EXTERNAL_INSTANCE_STATUS" &>> /var/log/gcp-failoverd/default.log
        sleep 2
      done
      echo "Sleeping for 5 secs...."  &>> /var/log/gcp-failoverd/default.log
      sleep 5
      EXTERNAL_INSTANCE_STATUS=$(gcloud compute instances describe --zone=${EXTERNAL_INSTANCE_ZONE} $EXTERNAL_INSTANCE_NAME --format='get(status)')
      if [[ $EXTERNAL_INSTANCE_STATUS == "TERMINATED" ]];
      then
        echo "The instance $EXTERNAL_INSTANCE_NAME has a status of $EXTERNAL_INSTANCE_STATUS" &>> /var/log/gcp-failoverd/default.log
        #Delete the access config from the terminated node
        until gcloud compute instances delete-access-config --zone=${EXTERNAL_INSTANCE_ZONE} $EXTERNAL_INSTANCE_NAME --access-config-name=${EXTERNAL_ACCESS_CONFIG} &>> /var/log/gcp-failoverd/default.log; do
          echo "Trying to Delete the access config from $INTERNAL_INSTANCE_NAME" &>> /var/log/gcp-failoverd/default.log
          sleep 2
        done
      fi
    fi
    # Assign Access Config to me because now I am the MASTER!
    until gcloud compute instances add-access-config $(hostname) --zone $ZONE --access-config-name "$(hostname)-access-config" --address $EXTERNAL_IP &>> /var/log/gcp-failoverd/default.log; do
      echo "Trying to assign IP access config to me because now I am the MASTER!" &>> /var/log/gcp-failoverd/default.log
      sleep 2
    done
    echo "I became the MASTER of ${EXTERNAL_IP} at: $(date)" >> /var/log/gcp-failoverd/default.log
    external_status=false
  else
    external_status=false
  fi
  echo "External IP Status $external_status at $(date)" >> /var/log/gcp-failoverd/default.log
  echo "Internal IP Status $internal_status at $(date)" >> /var/log/gcp-failoverd/default.log
  sleep 2
done