aws-scripts/elastic-beanstalk-set-hostname-within-instance.sh at master · pwpaing/aws-scripts · GitHub

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#!/usr/bin/env bash
# This script sets the hostname on Elastic Beanstalk servers from within the instance with their EB environment name and public IP address
# Requires "ec2:Describe*" IAM Policy

# Update boto
pip install --upgrade boto

# Remove any previous scripts
function cleanup(){
  if [ -f /home/ec2-user/ebenvironmentname.py ]; then
    rm -f /home/ec2-user/ebenvironmentname.py
  fi
  if [ -f /home/ec2-user/sethostname.sh ]; then
    rm -f /home/ec2-user/sethostname.sh
  fi
}

cleanup

# Create the Python script to detect EB Environment
cat > /home/ec2-user/ebenvironmentname.py <<- EOF
#!/usr/bin/env python

import boto.utils
import boto.ec2

iid_doc = boto.utils.get_instance_identity()['document']
region = iid_doc['region']
instance_id = iid_doc['instanceId']

ec2 = boto.ec2.connect_to_region(region)
instance = ec2.get_only_instances(instance_ids=[instance_id])[0]
env = instance.tags['elasticbeanstalk:environment-name']

print(env)
EOF

chmod +x /home/ec2-user/ebenvironmentname.py

# Set Hostname
{
  echo '#!/usr/bin/env bash'
  echo ebenvironmentname=\$\(/usr/bin/env python /home/ec2-user/ebenvironmentname.py\)
  echo sudo hostname '"$ebenvironmentname"'-"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"
} >> /home/ec2-user/sethostname.sh
chmod +x /home/ec2-user/sethostname.sh

cd /home/ec2-user/ && ./sethostname.sh

# Make hostname resolvable
{
  cat /etc/hosts
  echo 127.0.0.1 $(hostname)
} > /tmp/hosts
sort /tmp/hosts | uniq > /etc/hosts

# Persist changes over reboot
if ! [ -f /home/ec2-user/crontab.bk ]; then
  cp /etc/crontab /home/ec2-user/crontab.bk
fi
/bin/cp -f /home/ec2-user/crontab.bk /etc/crontab
echo '@reboot root bash /opt/elasticbeanstalk/hooks/appdeploy/post/98_set_hostname.sh' >> /etc/crontab

cleanup