This tool will request and set temporary credentials in your shell environment variables for a given role.

Installation

If you have a working Go 1.19 environment:

$ go install github.com/90poe/assume-role@v1.0.0

Configuration

Setup a profile for each role you would like to assume in ~/.aws/config.

For example:

~/.aws/config:

[profile usermgt]
region = us-east-1

[profile stage]
# Stage AWS Account.
region = us-east-1
role_arn = arn:aws:iam::1234:role/SuperUser
source_profile = usermgt

[profile prod]
# Production AWS Account.
region = us-east-1
role_arn = arn:aws:iam::9012:role/SuperUser
mfa_serial = arn:aws:iam::5678:mfa/eric-holmes
source_profile = usermgt

~/.aws/credentials:

[usermgt]
aws_access_key_id = AKIMYFAKEEXAMPLE
aws_secret_access_key = wJalrXUtnFEMI/K7MDENG/MYxFAKEYEXAMPLEKEY

Reference: https://docs.aws.amazon.com/cli/latest/userguide/cli-roles.html

In this example, we have three AWS Account profiles:

• usermgt
• stage
• prod

Each member of the org has their own IAM user and access/secret key for the usermgt AWS Account. The keys are stored in the ~/.aws/credentials file.

The stage and prod AWS Accounts have an IAM role named SuperUser. The assume-role tool helps a user authenticate (using their keys) and then assume the privilege of the SuperUser role, even across AWS accounts!

Usage

Perform an action as the given IAM role:

$ assume-role stage aws iam get-user

The assume-role tool sets AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_SESSION_TOKEN environment variables and then executes the command provided.

If the role requires MFA, you will be asked for the token first:

$ assume-role prod aws iam get-user
MFA code: 123456

If no command is provided, assume-role will output the temporary security credentials:

$ assume-role prod
export AWS_ACCESS_KEY_ID="ASIAI....UOCA"
export AWS_SECRET_ACCESS_KEY="DuH...G1d"
export AWS_SESSION_TOKEN="AQ...1BQ=="
export AWS_SECURITY_TOKEN="AQ...1BQ=="
export ASSUMED_ROLE="prod"
# Run this to configure your shell:
# eval $(assume-role prod)

Or windows PowerShell:

$env:AWS_ACCESS_KEY_ID="ASIAI....UOCA"
$env:AWS_SECRET_ACCESS_KEY="DuH...G1d"
$env:AWS_SESSION_TOKEN="AQ...1BQ=="
$env:AWS_SECURITY_TOKEN="AQ...1BQ=="
$env:ASSUMED_ROLE="prod"
# Run this to configure your shell:
# assume-role.exe prod | Invoke-Expression

If you use eval $(assume-role) frequently, you may want to create a alias for it:

• zsh

alias assume-role='function(){eval $(command assume-role $@);}'

• bash

function assume-role { eval $( $(which assume-role) $@); }

TODO

• Cache credentials.