Get IP address of EC2 Instance via the "Name" Tag, using "aws cli"

.ec2instances.bash

# Uses `aws cli` to get list of *running* EC2 instances, queried by the "Value"
# of the Tag "Name".
# In the case of Beanstalk EC2 instances, that "Name" is usually the same as the
# name of the Beanstalk cluster.
#
# To install, either copy this function to your .bashrc/.bash_profile/.zprofile,
# or save the file in your home directory and add `source .ec2instances.bash` to
# one of the files above or whatever file is correct for your shell.
#
# Usage:
#   ec2instances [name]
#     - `name` is a string, and can include wildcard characters.
#       If using wildcards, be sure to escape them or wrap name in quotes.
#
# Returns a JSON array of objects containing the instance ID, names, and IPs.
#
# Example:
# $ ec2instances someserver\*
#
# [
#   {
#     "InstanceId": "i-0afed43727f4132e8",
#     "PrivateIpAddress": "172.16.84.121",
#     "PublicIpAddress": null, # this server doesn't have one
#     "Name": "someserver-1"
#   }
# ]
#
ec2instances() {
  if [ -z "$1" ]; then
    echo "usage: ec2instances <instance-name>"
    echo ""
    echo "<instance-name> can use '*' as wildcard character, but will need to either"
    echo "be escaped (ex: server\\*) or wrapped in quotes (ex: \"server*\")."

    return -1
  fi
  
  aws ec2 describe-instances \
    --filters "Name=tag:Name,Values=$1" \
    --query "
      Reservations[*].Instances[?State.Name=='running'].[
        {
          "InstanceId": InstanceId,
          "PrivateIpAddress": PrivateIpAddress,
          "PublicIpAddress": PublicIpAddress,
          "Name": Tags[?Key=='Name'].Value | [0]
        }
      ][0]
    "
}