describe-ec2-instance.sh

#!/bin/bash

set -e

NAME=$1
[[ -z $NAME ]] && {
  echo "Usage: $0 INSTANCE_NAME" >&2
  exit 1
}

REGIONS='us-east-1 us-west-1 eu-west-1'

declare -a instance_ids
declare -a instance_ips
declare -a instance_regions
count=0
for region in $REGIONS; do
  while read key value; do
    [[ $key = 'INSTANCES' ]] || continue
    set -- $value
    shift 8
    [[ $7 =~ ^[0-9.]+$ ]] || continue
    (( ++count ))
    instance_regions[count - 1]=$region
    instance_ids[count - 1]=$1
    instance_ips[count - 1]=$7
  done < <( aws ec2 describe-instances --filters "Name=tag:Name,Values=$NAME" --region $region --output text )
done

(( count == 0 )) && {
  echo "Instance named $NAME not found" >&2
  exit 2
}

(( count > 1 )) && {
  echo "Multiple instances named $NAME found:" >&2
  for (( i = 0; i < count; ++i )); do
    echo "${instance_regions[i]} ${instance_ids[i]} ${instance_ips[i]}" >&2
  done
  exit 3
}

echo "${instance_regions[i]} ${instance_ids[i]} ${instance_ips[i]}"