Generate a Report of EC2 Instances by Type, Running Time, and Region

This guide will walk you through how to create a list of EC2 Instances based on their types, running time, and region using AWS JavaScript Software Development Kit (SDK).

Code

const AWS = require('aws-sdk');

const ec2 = new AWS.EC2({ apiVersion: '2021-04-27', region: 'us-west-2' });

const params = {
    MaxResults: 100,
};

ec2.describeInstances(params, function(err, data) {
    if (err) {
        console.log("Error", err.stack);
    } else {
        let instances = [];
        data.Reservations.forEach((res) => {
            res.Instances.forEach((inst) => {
                instances.push({
                    InstanceId: inst.InstanceId,
                    InstanceType: inst.InstanceType,
                    LaunchTime: inst.LaunchTime,
                    Region: 'us-west-2',
                });
            });
        });
        console.log(JSON.stringify(instances, null, 2));
    }
});

Detailed Code Explanation

We start by requiring the aws-sdk module and creating a service object ec2 using the AWS.EC2 constructor, set to the us-west-2 region.

We then define the params object to specify the maximum number of instances that AWS.EC2.describeInstances should return.

The describeInstances method is then called with params. If an error occurs, we print the error; otherwise, we process the returned data.

We loop through each Reservation and Instance nested within, pushing an object containing the InstanceId, InstanceType, LaunchTime, and Region to the instances array.

Finally, we stringify the instances array into a pretty JSON format and log it to the console.

Expected Output Format

The expected output is an array of objects, each representing an instance, in JSON format.

[
    {
        "InstanceId": "i-0abcdef1234567890",
        "InstanceType": "t2.micro",
        "LaunchTime": "2021-04-27T14:00:00.000Z",
        "Region": "us-west-2"
    },
    {...}
]

Considerations & Caveats

• The returned information only includes instances for the specified region (in this case, us-west-2).
• You're only returning information about a maximum of 100 instances due to the MaxResults parameter.
• The describeInstances function used here retrieves information about instances whether they're running or stopped.

Required IAM Permissions and Example Policy

Your IAM user or role must have the ec2:DescribeInstances permission. Here's an example policy that grants this permission:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": "ec2:DescribeInstances",
            "Resource": "*"
        }
    ]
}

FAQ

Q: Why do I need the aws-sdk module?

A: The aws-sdk module allows your script to interact with AWS services.

Q: Can I use this script to get details from other AWS regions?

A: Yes, you can replace us-west-2 in region: 'us-west-2' with the desired region.

Q: What if I want more than 100 instances?

A: You can adjust MaxResults parameter accordingly but keep in mind AWS may limit the number of instances returned in one call for API throttling reasons.

Q: Can I filter the instances by their statuses?

A: Yes, you can add Filters to the params object to specify the instance state.