EC2 Metadata API basics

metadata.sh

# https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

METADATA_TOKEN="$(curl -s -X PUT 'http://169.254.169.254/latest/api/token' -H 'X-aws-ec2-metadata-token-ttl-seconds: 21600')"
AVAILABILITY_ZONE="$(curl -s -H "X-aws-ec2-metadata-token: $METADATA_TOKEN" http://169.254.169.254/latest/meta-data/placement/availability-zone)"
export AWS_REGION="$(echo "$AVAILABILITY_ZONE" | rev | cut -c 2- | rev)"
export AWS_DEFAULT_REGION="$AWS_REGION"
export INSTANCE_ID="$(curl -s -H "X-aws-ec2-metadata-token: $METADATA_TOKEN" http://169.254.169.254/latest/meta-data/instance-id)"

# Instance identity documents is another very useful interface with many key value pairs in json format
# https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html
curl -s -H "X-aws-ec2-metadata-token: $METADATA_TOKEN" http://169.254.169.254/latest/dynamic/instance-identity/document
# {
#   "accountId" : "111111111111",
#   "architecture" : "x86_64",
#   "availabilityZone" : "us-east-1a",
#   ...
#   "imageId" : "ami-0123456789",
#   "instanceType" : "t2.small",
#   ...
#   "pendingTime" : "2021-08-04T16:20:26Z",
#   "privateIp" : "10.0.0.1",
#   ...
#   "region" : "us-east-1",
#   "version" : "2017-09-30"
# }