AWS EC2インスタンス起動時 cloud-initによりホスト名をNameタグ_インスタンスID_IPアドレスに設定する ref: http://qiita.com/na0AaooQ/items/d18a0df8d147e51a04a2

file0.txt

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "ec2:Describe*",
      "Resource": "*"
    }
  ]
}

file1.txt

[ec2-user@ip-172-31-4-80 ~]$ hostname
ip-172-31-4-80
[ec2-user@ip-172-31-4-80 ~]$ sudo vi /var/lib/cloud/scripts/per-boot/001_setting_hostname.sh
#!/bin/sh

##### リージョン名を取得
REGION=`/usr/bin/curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone/ | sed 's/.$//'`

##### インスタンス自身のインスタンスIDを取得
INSTANCE_ID=`/usr/bin/curl -s http://169.254.169.254/latest/meta-data/instance-id`

##### インスタンス自身のIPアドレスを取得
IP_ADDRESS=`/usr/bin/curl -s http://169.254.169.254/latest/meta-data/local-ipv4`

##### Nameタグを取得
NAME_TAG=`/usr/bin/aws ec2 describe-instances --region ${REGION} --instance-ids ${INSTANCE_ID=} --query 'Reservations[].Instances[].Tags[?Key==\`Name\`].Value' --output text`

##### ホスト名の一部に設定するIPアドレスの.を-に変換
IP_ADDRESS=`echo ${IP_ADDRESS} | sed -e "s/\./-/g"`

##### ホスト名を変更する
INSTANCE_NAME="${NAME_TAG}_${INSTANCE_ID}_${IP_ADDRESS}"

hostname ${INSTANCE_NAME}
sed -i -e "s/^HOSTNAME=.*\$/HOSTNAME=${INSTANCE_NAME}/g" /etc/sysconfig/network

file2.txt

[ec2-user@ip-172-31-4-80 ~]$ sudo chmod 755 /var/lib/cloud/scripts/per-boot/001_setting_hostname.sh
[ec2-user@ip-172-31-4-80 ~]$
[ec2-user@ip-172-31-4-80 ~]$ ll /var/lib/cloud/scripts/per-boot/001_setting_hostname.sh
-rwxr-xr-x 1 root root 969 Dec 28 00:32 /var/lib/cloud/scripts/per-boot/001_setting_hostname.sh
[ec2-user@ip-172-31-4-80 ~]$

file3.txt

[ec2-user@ip-172-31-4-80 ~]$ hostname
ip-172-31-4-80
[ec2-user@ip-172-31-4-80 ~]$ grep -i hostname /etc/sysconfig/network
HOSTNAME=localhost.localdomain
[ec2-user@ip-172-31-4-80 ~]$ sudo reboot

file4.txt

[ec2-user@web-server-002_i-9b6f5f82_172-31-4-80 ~]$ hostname
web-server-002_i-9b6f5f82_172-31-4-80
[ec2-user@web-server-002_i-9b6f5f82_172-31-4-80 ~]$ grep -i hostname /etc/sysconfig/network
HOSTNAME=web-server-002_i-9b6f5f82_172-31-4-80
[ec2-user@web-server-002_i-9b6f5f82_172-31-4-80 ~]$