Make the SSH connection to EC2 instances easier by requiring only tag values instead of IP addresses.

aws-connect.sh

#!/usr/bin/env bash
set -euo pipefail

# ======================================================================================================================
# Make the SSH connection to EC2 instances easier by requiring only tag values instead of IP addresses.
#
# Usage:
# bash aws-connect.sh <environment> <bastion|apache|nginx|...> <index>
#
# Examples:
# SSH to the bastion: bash aws-connect.sh <environment> bastion
# SSH to the first Apache instance: bash aws-connect.sh <environment> apache
# SSH to the second Apache instance: bash aws-connect.sh <environment> apache 2
# ======================================================================================================================

# Validate arguments passed to the script
if [[ ($# -eq 2 || $# -eq 3) && -n "$1" && -n "$2" ]]; then
    environment="$1"
    instance_type="$2"

    if [[ $# -eq 3 && $3 =~ ^[0-9]+$ ]]; then
        instance_index=$(( $3 - 1 ))
    else
        instance_index=0
    fi
else
    echo "Usage: bash aws-connect.sh <environment> <bastion|apache|nginx|...> <index>"
    exit 1
fi

# Retrieve the bastion public IP address
bastion_ip=$(aws ec2 describe-instances \
    --filters "Name=tag:Environment,Values=${environment}" "Name=tag:Name,Values=${environment}-bastion" "Name=instance-state-name,Values=running" \
        | jq -r ".Reservations[0].Instances[0].PublicIpAddress"
)

# Retrieve the remote private IP address
remote_ip=$(aws ec2 describe-instances \
    --filters "Name=tag:Environment,Values=${environment}" "Name=tag:Name,Values=${environment}-${instance_type}" "Name=instance-state-name,Values=running" \
        | jq -r ".Reservations[${instance_index}].Instances[0].PrivateIpAddress"
)

# Execute the SSH connection
if [[ "${instance_type}" == "bastion" ]]; then
    ssh ec2-user@"${bastion_ip}" -A
else
    ssh ec2-user@"${bastion_ip}" -A -t ssh ec2-user@"${remote_ip}"
fi