little shell script which can be sourced to act on behalf of an IAM role in AWS.

assume-role.sh

#!/usr/bin/env sh

# this script will modify your environment
# so that you can work in the context of an assumed role in AWS

set -u

if [ -z ${ASSUME_ROLE_ARN+x} ]
then
  echo "NO ASSUME_ROLE_ARN variable configured in Environment.";
  exit 1;
fi

# fetch credentials
CREDENTIALS=$(aws sts assume-role --role-arn $ASSUME_ROLE_ARN --role-session-name ci-pipeline --output text | awk 'NR==2')

# set relevant env vars
export AWS_ACCESS_KEY_ID=$(echo $CREDENTIALS | cut -d " " -f 2);
export AWS_SECRET_ACCESS_KEY=$(echo $CREDENTIALS | cut -d " " -f 4);
export AWS_SESSION_TOKEN=$(echo $CREDENTIALS | cut -d " " -f 5);