Introduction to Amazon Web Services Identity and Access Management

Using AWS Identity and Access Management you can create separate users and permissions to use any AWS service, for instance EC2, and avoid giving other people your Amazon username, password or private key.

You can set very granular permissions, on users, groups, specific resources, and a combination of them. It will become really complex soon! But there are several very common use cases, that IAM is useful for. For instance having a AWS account for a team of developers.

Getting started

You can go through the Getting Started Guide, but I’ll save you some time:

Download IAM command line tools

Store your AWS credentials in a file, ie. ~/account-key

AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE
AWSSecretKey=wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY

Configure environment variables

export AWS_IAM_HOME=<path_to_cli>
export PATH=$AWS_IAM_HOME/bin:$PATH
export AWS_CREDENTIAL_FILE=~/account-key

Creating an admin group

When you have IAM setup, the next step is to create an Admins group where you can add yourself

iam-groupcreate -g Admins

Create a policy in a file, ie. MyPolicy.txt

{
   "Statement":[{
      "Effect":"Allow",
      "Action":"*",
      "Resource":"*"
      }
   ]
}

Upload the policy

iam-groupuploadpolicy -g Admins -p AdminsGroupPolicy -f MyPolicy.txt

Creating an admin user

Create an admin user with

iam-usercreate -u YOUR_NAME -g Admins -k -v

The response looks similar to this:

AKIAIOSFODNN7EXAMPLE
wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY
arn:aws:iam::123456789012:user/YOUR_NAME
AIDACKCEVSQ6C2EXAMPLE

The first line is your Access Key ID; the second line is your Secret Access Key. You need to save these IDs.

Save your Access Key ID and your Secret Access Key to a file called for instance ~/YOUR_NAME_cred.txt. You can use those credentials from now on instead of the global AWS credentials for the whole account.

export AWS_CREDENTIAL_FILE=~/YOUR_NAME_cred.txt

Creating a dev group

Let’s create an example dev group where the users will have only read access to EC2 operations.

 iam-groupcreate -g dev

Now we need to set the group policy to allow all EC2 Describe* actions, which are the ones that allow users to see data, but not to change it. Create a file MyPolicy.txt with these contents

{
  "Statement": [
     {
       "Sid": "EC2AllowDescribe",
       "Action": [
         "ec2:Describe*"
       ],
       "Effect": "Allow",
       "Resource": "*"
     }
   ]
 }

Now upload the policy

iam-groupuploadpolicy -g dev -p devGroupPolicy -f MyPolicy.txt

Creating dev users

To create a new AWS user under the dev group

iam-usercreate -u username -g dev -k -v

Create a login profile for the user to log into the web console

iam-useraddloginprofile -u username -p password

The user can now access the AWS console at

https://your_AWS_Account_ID.signin.aws.amazon.com/console/ec2

Or you can make life easier by creating an alias

 iam-accountaliascreate -a maestrodev

and now the console is available at

https://maestrodev.signin.aws.amazon.com/console/ec2

About Policies

AWS policy files can be really complex. The AWS Policy Generator will help as a start point and see what actions can be used, but it won’t help you making them easier to read (using wildcards) or applying them to specific resources. Amazon could have provided a better generator tool allowing you to choose your own resources (users, groups, S3 buckets,…) from a easy to use interface and not having to lookup all sorts of crazy AWS identifiers. Hopefully they will be provide a comprehensive tool as part of the AWS Console.

There is more information available at the IAM User Guide.

Update

Just after I wrote this post Amazon has made IAM available in the AWS management console, which makes using IAM way easier.

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