Now that we have a mechanism of automating the generation of temporary session credentials, assuming that your packer.json file and Makefile are in the root of your packer-ecs repository, let's test out building your Packer image by running make build:
> export AWS_PROFILE=docker-in-aws> make buildEnter MFA code for arn:aws:iam::385605022855:mfa/justin.menga: ******packer build packer.jsonamazon-ebs output will be in this color.==> amazon-ebs: Prevalidating AMI Name: docker-in-aws-ecs 1518934269 amazon-ebs: Found Image ID: ami-5e414e24==> amazon-ebs: Creating temporary keypair: packer_5a8918fd-018d-964f-4ab3-58bff320ead5==> amazon-ebs: Creating temporary security group for this instance: packer_5a891904-2c84-aca1-d368-8309f215597d ...