ec2-env

This tool retrieves information about the EC2 instance that runs it and prints them formatted environment variables. The output can be eval'd by bash or written to a file with the -file option.

Usage

Calling the tool will output environment variables to stdout:

eval $(ec2-env)

Alternatively you can write an environment file:

ec2-env -file=/etc/environment.ec2

This second usage is useful for integraiton with systemd unit files using the EnvironmentFile option.

Variables

The following environment variables are written by ec2-env:

Environment Variable Name	Description
EC2_AVAILABILITY_ZONE	AWS availability zone.
EC2_AVAILABILITY_ZONE_LETTER	The letter (a, b, c, etc) of the availability zone.
EC2_REGION	AWS region (us-east-1, etc).
EC2_REGION_SHORT	A shortened region identifier.
EC2_INSTANCE_ID	EC2 instance ID.
EC2_INSTANCE_TYPE	EC2 instance type.
EC2_ACCOUNT_ID	AWS Account ID.
EC2_IMAGE_ID	EC2 instance AMI.
EC2_PRIVATE_DNS	EC2 instance private DNS name.
EC2_PRIVATE_IP	EC2 instance private IP address.
EC2_PUBLIC_DNS	EC2 instance public DNS name.
EC2_PUBLIC_IP	EC2 instance public IP address.
EC2_SUBNET_ID	ID of the subnet the instance is running in.
EC2_VPC_ID	ID of the VPC the instance is running in.
EC2_KEYNAME	EC2 key name.
EC2_NAMESERVER	EC2 nameserver assigned to the instance.
EC2_TAG_%s	EC2 tags. These are templated. See Instance Tags.

Instance Tags

The instance's tags are also written to environment variables. Each tag is written to a variable of the form EC2_TAG_%s where %s is the sanitized tag name.

Tag names are sanitized by converting to uppercase and replacing non-alphanumeric characters to underscores. Multiple underscores are replaced with a single underscore after replacement.

Some basic examples:

• Environment to EC2_TAG_ENVIRONMENT
• DatabaseName to EC2_TAG_DATABASENAME
• env--role to EC2_TAG_ENV_ROLE
• aws:autoscaling:groupName to EC2_TAG_AWS_AUTOSCALING_GROUPNAME

Example Unit File

The following unit file can be used to run the ecr-env tool on boot:

[Unit]
Description=Retrieve AWS EC2 environment
After=network.target
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/opt/bin/ec2-env -file=/etc/environment.ec2