shell script to ease MFA use with aws role assumption

assumeawsrole

#!/bin/bash

if [[ $# -ne 1 ]]; then
    echo "usage: $0 <rolename> (e.g. \`$0 EngineerProd\`)" > /dev/stderr
    exit 127
fi

if ! which jq 2>&1 > /dev/null ; then
    echo "$0 error: Please install 'jq'." > /dev/stderr
    exit 127
fi

if ! which aws 2>&1 > /dev/null ; then
    echo "$0 error: Please install 'awscli'." > /dev/stderr
    exit 127
fi


USERARN="$(aws --output json iam get-user | jq -r .User.Arn)"

if [[ -z "$USERARN" ]]; then
    echo "$0 error: unable to determine AWS IAM user.  Did you run 'aws configure'?" > \
        /dev/stderr
    exit 128
fi

IAMUSER="$(basename $USERARN)"
ACCOUNT="$(echo $USERARN | cut -d: -f5)"
REGION="us-east-1"
ROLEARN="arn:aws:iam::$ACCOUNT:role/$1"
MFAARN="arn:aws:iam::$ACCOUNT:mfa/$IAMUSER"

echo -n "Enter MFA token code for $MFAARN: "
read -s MFACODE
echo ""

RESP="$(aws --region $REGION sts assume-role \
    --role-arn $ROLEARN \
    --role-session-name assumption-$IAMUSER-$(date +%s) \
    --serial-number $MFAARN --token-code $MFACODE 2> /dev/null )"

AKI="$(echo $RESP | jq -r .Credentials.AccessKeyId)"

if [[ -z "$AKI" ]]; then
    echo "Failure." > /dev/null
    exit 129
fi
        
SAK="$(echo $RESP | jq -r .Credentials.SecretAccessKey)"
ST="$(echo $RESP | jq -r .Credentials.SessionToken)"

echo "export AWS_ACCESS_KEY_ID=\"$AKI\""
echo "export AWS_SECRET_ACCESS_KEY=\"$SAK\""
echo "export AWS_SESSION_TOKEN=\"$ST\""