Getting a taste of the AWS command line interface

In this article I'll briefly demonstrate how we can access the AWS command line interface from an EC2 instance.

I've launched an Amazon Linux AMI instance and attached a role to it. I won't go through the entire instance launch wizard but I'll show you the step where I specified the role which is step 3 (Configure instance).

I have created a role of the type Amazon EC2 and attached EC2FullAccess policy with this role as shown in the below screenshot:

This will allow the instance to have access to all EC2 related actions from the AWS command line interface.

I used an IAM role here because the instance I'm using resides in my EC2 environment. In case you want to use AWS cli from an on premises server then you could create an IAM, generate access keys for that user and attach the appropriate policies to that user. You can then install AWS cli on your on premises instance and use the IAM users' access keys for authentication to AWS while running commands.

I chose to build an instance from the Amazon Linux AMI because it comes pre-configured with the AWS cli. But we can install it on other Linux variants fairly easily via pip.


The syntax to run an AWS cli command is as follows:

aws <service> <action>

To use help you can type aws help to get information on available commands for all services or type aws ec2 help to get information on available EC2 related commands only.

Here are examples of the same:

[ec2-user@ip-172-31-23-118 ~]$ aws help | more
AWS()                                                                    AWS()



NAME
       aws -

DESCRIPTION
       The  AWS  Command  Line  Interface is a unified tool to manage your AWS
       services.

SYNOPSIS
          aws [options] <command> <subcommand> [parameters]

       Use aws command help for information on a  specific  command.  Use  aws
       help  topics  to view a list of available help topics. The synopsis for
       each command shows its parameters and their usage. Optional  parameters
       are shown in square brackets.

OPTIONS
       --debug (boolean)

       Turn on debug logging.

       --endpoint-url (string)

       Override command's default URL with the given URL.

       --no-verify-ssl (boolean)

       By  default, the AWS CLI uses SSL when communicating with AWS services.
       For each SSL connection, the AWS CLI will verify SSL certificates. This



[ec2-user@ip-172-31-23-118 ~]$ aws ec2 help | more
EC2()                                                                    EC2()



NAME
       ec2 -

DESCRIPTION
       Amazon  Elastic Compute Cloud (Amazon EC2) provides resizable computing
       capacity in the Amazon Web Services (AWS) cloud. Using Amazon EC2 elim-
       inates your need to invest in hardware up front, so you can develop and
       deploy applications faster.

AVAILABLE COMMANDS
       o accept-reserved-instances-exchange-quote

       o accept-vpc-peering-connection


Now, after viewing the help pages lets run describe-instances command for EC2.

[ec2-user@ip-172-31-23-118 ~]$ aws ec2 describe-instances
You must specify a region. You can also configure your region by running "aws configure".
[ec2-user@ip-172-31-23-118 ~]$

As you may observe from the output we need to run aws configure first to set a few parameters.

[ec2-user@ip-172-31-23-118 ~]$ aws configure
AWS Access Key ID [None]:
AWS Secret Access Key [None]:
Default region name [None]: US East
Default output format [None]:
[ec2-user@ip-172-31-23-118 ~]$ aws ec2 describe-instances

Invalid endpoint: https://ec2.US East.amazonaws.com

This throws an error because I wrote the region name incorrectly.
To correct this you could run aws configure again or edit the file ~/.aws/config.

[ec2-user@ip-172-31-23-118 .aws]$ ls
config
[ec2-user@ip-172-31-23-118 .aws]$ cat config
[default]
region = US East


[ec2-user@ip-172-31-23-118 ~]$ cd .aws/
[ec2-user@ip-172-31-23-118 .aws]$ cat config
[default]
region = us-east-1


Now when I run the describe-instances command I should get the desired output.

[ec2-user@ip-172-31-23-118 ~]$ aws ec2 describe-instances | more
{
    "Reservations": [
        {
            "OwnerId": "242386062125",
            "ReservationId": "r-02d7e6663b8d8dde5",
            "Groups": [],
            "Instances": [
                {
                    "Monitoring": {
                        "State": "disabled"
                    },
                    "PublicDnsName": "ec2-54-147-27-195.compute-1.amazonaws.com",
                    "State": {
                        "Code": 16,
                        "Name": "running"



Now lets view the AWS regions available to us:

[ec2-user@ip-172-31-23-118 ~]$ aws ec2 describe-regions
{
    "Regions": [
        {
            "Endpoint": "ec2.ap-south-1.amazonaws.com",
            "RegionName": "ap-south-1"
        },
        {
            "Endpoint": "ec2.eu-west-2.amazonaws.com",
            "RegionName": "eu-west-2"
        },
        {
            "Endpoint": "ec2.eu-west-1.amazonaws.com",
            "RegionName": "eu-west-1"
        },
        {
            "Endpoint": "ec2.ap-northeast-2.amazonaws.com",
            "RegionName": "ap-northeast-2"
        },
        {
            "Endpoint": "ec2.ap-northeast-1.amazonaws.com",
            "RegionName": "ap-northeast-1"
        },
        {
            "Endpoint": "ec2.sa-east-1.amazonaws.com",
            "RegionName": "sa-east-1"
        },
        {
            "Endpoint": "ec2.ca-central-1.amazonaws.com",
            "RegionName": "ca-central-1"
        },
        {
            "Endpoint": "ec2.ap-southeast-1.amazonaws.com",
            "RegionName": "ap-southeast-1"
        },
        {
            "Endpoint": "ec2.ap-southeast-2.amazonaws.com",
            "RegionName": "ap-southeast-2"
        },
        {
            "Endpoint": "ec2.eu-central-1.amazonaws.com",
            "RegionName": "eu-central-1"
        },
        {
            "Endpoint": "ec2.us-east-1.amazonaws.com",
            "RegionName": "us-east-1"
        },
        {
            "Endpoint": "ec2.us-east-2.amazonaws.com",
            "RegionName": "us-east-2"
        },
        {
            "Endpoint": "ec2.us-west-1.amazonaws.com",
            "RegionName": "us-west-1"
        },
        {
            "Endpoint": "ec2.us-west-2.amazonaws.com",
            "RegionName": "us-west-2"
        }
    ]
}


This concludes this brief but insightful introduction to the AWS command line interface.
I hope this article was helpful to you and I thank you for reading.