Connect to running AWS instances using tag names

awssh.sh

#!/bin/bash

####################################################
# Connect to running AWS instances using tag names #
# Author: [email protected]                 #
####################################################

PEM_FILE="$HOME/.ssh/aws.pem";
DEFAULT_USERNAME="ubuntu";

function print_running_instances {
  printf "Running instances:\n";
  aws ec2 describe-instances --filter "Name=instance-state-name,Values=running" --query "Reservations[*].Instances[*].[Tags[?Key=='Name'].Value[],PublicIpAddress]" --output=text \
  | xargs -n2 \
  | awk -v bold=$(tput bold) -v normal=$(tput sgr0) '{print bold $2 normal " (" $1 ")"}' \
  | column -t;
}

function connect_to_instance {
  ip=$(aws ec2 describe-instances --filter "Name=tag:Name,Values=$1" "Name=instance-state-name,Values=running" --query "Reservations[*].Instances[*].PublicIpAddress" --output=text);
  printf "Connecting to $ip\n"
  if [ -z "$ip" ]; then
    printf "Could not find a running instance tagged '$1'\n";
    print_running_instances;
    exit 1;
  fi
  ssh -i $PEM_FILE $username@$ip;
}

if [ $# -eq 0 ]
  then
    printf "Usage: $0 <instance name> [username]\n\n";
    print_running_instances;
    printf "\nusername defaults to 'ubuntu'\n\n";
    exit 1;
fi

if [ ! -r $PEM_FILE ]
  then
    printf "The private key file $PEM_FILE is missing or unreadable. If you have used a different filename, please rename it or run:\n\n    ln -s <path to pem file> $PEM_FILE\n\n";
    exit 1;
fi

username=$DEFAULT_USERNAME;
if [ $# -eq 2 ]
  then
   username=$2;
fi
 
connect_to_instance $1;