set AWS Access Token Environments by sts:AssumeRole on AWS

awsu.bash

#!/bin/bash

# description:
#   this is a printer to set environments for AWS Access Token gotten by sts:AssumeRole.
#   cf. https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp_use-resources.html
#   the IAM Role MUST be configured to be able to assume it by your account.
# practical usage:
#   $ eval $(awsu.bash <ROLE_ARN>)

TARGET_ROLE_ARN="$1"


function Aws::Sts::get_session_token () {
    aws sts assume-role \
        --role-arn "$1" \
        --role-session-name "$(uuidgen)" \
        --query 'Credentials'
}


unset AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY AWS_SESSION_TOKEN

credential_json=$(mktemp)

Aws::Sts::get_session_token "${TARGET_ROLE_ARN}" \
    >"${credential_json}"

echo "export AWS_ACCESS_KEY_ID=$(jq -r '.AccessKeyId' ${credential_json})"
echo "export AWS_SECRET_ACCESS_KEY=$(jq -r '.SecretAccessKey' ${credential_json})"
echo "export AWS_SESSION_TOKEN=$(jq -r '.SessionToken' ${credential_json})"

rm -f "${credential_json}"