Configure Locksmith

Before you can use Locksmith, you must create an IAM user and configure
Locksmith with its credentials. Locksmith can be both used stand-alone and
managed by a service. Here we show how to use Locksmith as a stand-alone tool.

Because of the nature how assuming a role works, it is important that you use
a personal account (i.e., an account that nobody else has access to) for
creating your IAM user!

It is strongly recommend creating a new account dedicated to holding this single
IAM user.

Create an IAM user

First, we are going to create an IAM user.
The only function this user is going to fulfil is assuming roles in other AWS
accounts. You MUST create this new IAM user in a new personal account, dedicated
to nothing else than holding this single IAM user. You must not do anything else
with this account (except enabling CloudTrail).

Create an IAM user:

Choose access type “Programmatic access” only
Do not select “AWS Management Console access”
Choose “Attach existing policies directly”
Click “Create policy”

Click “Create Your Own Policy”, and fill the fields as follows:

Policy Name: stsAssumeRole
Description: Allow assuming IAM Roles.

Policy Document:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "sts:AssumeRole",
      "Resource": "*"
    }
  ]
}

Click “Create Policy”
Return to the user creation, “Refresh” the list of policies
Select the “Customer managed” policy “stsAssumeRole” that was just created
Click “Next: Review”
Review the settings:
Click “Create user”
Safely store the credentials for this user,
we are going to need this later
Find the user that was just created, and open the “Security credentials” tab
Click the pencil icon next to “Assigned MFA device” to start configuring
an MFA token for this IAM user
Configure a virtual or hardware MFA device
Make at note of the ARN/serial number of the MFA device