Steps:
Open and login to https://impex.europe-west1.gcp.commercetools.com/ page
Click to API Playground and choose your project
Choose ‘Extensions’ in Endpoint field and ‘Create’ in Command

destination.arn - ARN of your Lambda function destination.access* - credentials created previously key - unique identificator of extension. Should be set by user
{
"destination": {
"type": "AWSLambda",
"arn": "arn:aws:lambda:eu-central-1:907001314987:function:ExtensionTaxLambda",
"accessKey": "*****",
"accessSecret": "******"
},
"triggers": [
{
"resourceTypeId": "cart",
"actions": [
"Create",
"Update"
]
}
],
"key": "tax-extension"
}
