Instance Metadata in the Elastic Compute Cloud

This post will tell you how to access the instance’s metadata from the Elastic Compute Cloud.

Instance Metadata in the Elastic Compute Cloud:

Instance Metadata in the Elastic Compute Cloud is the information related to your data. Metadata can be categorized on the basis of the data that is unique to an instance and the data which is common for all the instances on EC2.

The Common Metadata includes:

• The instance – type : It can be a Linux, Ubuntu, windows, etc. based on the AMI you choose.
• Security Group : It can be modified accordingly and can be same for more than one instance.
• Key-Pair : All your instances can be accessed by a single key-pair.

The Unique Metadata includes:

• Instance –Id
• Public-Hostname
• Public IP Address

We proceed with launching and connecting to the instance.

When you launch an Ec2 instance, it appears in the Ec2 Dashboard like:

We are using an Ubuntu AMI.

After you SSH in it and the connection has been established to the instance, you give the command:

curl http://169.254.169.254/latest/meta-data

This command lists out the instance’s metadata. 169.254.169.254 is the IP used to access the metadata of the servers, present virtually on the cloud. Unlike other IP addresses, instead of routing , it fetches the server’s metadata for you.

The above snapshot lists the metadata of our Ubuntu instance which is helpful in extracting the instance details and differentiating  the instance.

Instance-ID : It is an unique identifier and a combination of numeric and alphanumeric values which are based on the resource allocation of a particular instance. How is this combination decided, only AWS  knows about this.

Though it can be clear from observation that:

• i – instance
• r – reservation
• vol – EBS volume
• snap – EBS snapshot
• ami – Amazon machine image
• aki – Amazon kernel image
• ari – Amazon ramdisk image

Instance Type : This tells what type memory, storage and compute power the instance possesses, e.g. This is a 615 Mb ubuntu machine.

Kernal- Id :

The Local Hostname can be known as:

Local-ipv4 :

Public-keys : The name of the key-pair is displayed.

The AMI-id can be known from the EC2 instance as:

AMI-launch-index :

Block Device Mapping :  ami, ephemeral, root.

Similarly, Various other data can be known as: