This is an old thread, but incase anybody finds it and has a similar need here is a solution that worked for me that got posted here
pm.sendRequest({
url: "https://ssm.eu-central-1.amazonaws.com",
method: "POST",
header: {
'Content-Type': 'application/x-amz-json-1.1',
'X-Amz-Target': 'AmazonSSM.GetParameter'
},
auth: {
type: "awsv4",
"awsv4": {
"accessKey": "$ACCESSKEY",
"secretKey": "$SECRET",
"region": "eu-central-1",
"service": "ssm",
"sessionToken": "$SESSION_TOKEN"
}
},
body: .....
}, function (err, response) {
....
});