first.json

{
  "variables": {
    "aws_access_key": "",
    "aws_secret_key": ""
  },
  "builders": [
    {
      "type": "amazon-ebs",
      "access_key": "{{user `aws_access_key`}}",
      "secret_key": "{{user `aws_secret_key`}}",
      "region": "ap-southeast-2",
      "source_ami": "ami-1f117325",
      "instance_type": "t1.micro",
      "ssh_username": "ubuntu",
      "ami_name": "packer-{{timestamp}}"
    }
  ],
  "provisioners": [
    {
      "type": "shell",
      "only": ["amazon-ebs"],
      "inline": ["mkdir -p /home/ubuntu/.ssh/"]
    },
    {
      "type": "file",
      "only": ["amazon-ebs"],
            "source": "/Users/kikitux/.ssh/id_rsa.pub",
            "destination": "/home/ubuntu/.ssh/authorized_keys"
    },
    {
      "type": "shell",
      "only": ["amazon-ebs"],
      "inline": ["sudo chmod -R 0600 /home/ubuntu/.ssh/; sudo chmod 0700 /home/ubuntu/.ssh/"]
    }
  ]
}

first.log

amazon-ebs output will be in this color.

==> amazon-ebs: Inspecting the source AMI...
==> amazon-ebs: Creating temporary keypair: packer 545ff0f5-9174-6895-327d-44be0be1f424
==> amazon-ebs: Creating temporary security group for this instance...
==> amazon-ebs: Authorizing SSH access on the temporary security group...
==> amazon-ebs: Launching a source AWS instance...
    amazon-ebs: Instance ID: i-1bfe75d4
==> amazon-ebs: Waiting for instance (i-1bfe75d4) to become ready...
==> amazon-ebs: Waiting for SSH to become available...
==> amazon-ebs: Connected to SSH!
==> amazon-ebs: Provisioning with shell script: /var/folders/zg/dw2mgnh135l9976wfs62tsmh0000gp/T/packer-shell985537322
    amazon-ebs:
    amazon-ebs:
    amazon-ebs:
    amazon-ebs:
    amazon-ebs:
    amazon-ebs:
    amazon-ebs:
==> amazon-ebs: Uploading /Users/kikitux/.ssh/id_rsa.pub => /home/ubuntu/.ssh/authorized_keys
==> amazon-ebs: Provisioning with shell script: /var/folders/zg/dw2mgnh135l9976wfs62tsmh0000gp/T/packer-shell246848067
==> amazon-ebs: Stopping the source instance...
==> amazon-ebs: Waiting for the instance to stop...
==> amazon-ebs: Creating the AMI: packer-1415573748
    amazon-ebs: AMI: ami-9d81eea7
==> amazon-ebs: Waiting for AMI to become ready...
==> amazon-ebs: Terminating the source AWS instance...
==> amazon-ebs: Deleting temporary security group...
==> amazon-ebs: Deleting temporary keypair...
Build 'amazon-ebs' finished.

==> Builds finished. The artifacts of successful builds are:
--> amazon-ebs: AMIs were created:

ap-southeast-2: ami-9d81eea7

second.json

{
  "variables": {
    "aws_access_key": "",
    "aws_secret_key": "",
    "ssh_private_key_file": "/Users/kikitux/.ssh/id_rsa"
  },
  "builders": [
    {
      "type": "amazon-ebs",
      "access_key": "{{user `aws_access_key`}}",
      "secret_key": "{{user `aws_secret_key`}}",
      "region": "ap-southeast-2",
      "ssh_private_key_file": "{{user `ssh_private_key_file`}}",
      "source_ami": "ami-9d81eea7",
      "instance_type": "t1.micro",
      "ssh_username": "ubuntu",
      "ami_name": "packer-{{timestamp}}"
    }
  ],
  "provisioners": [
    {
      "type": "shell",
      "only": ["amazon-ebs"],
      "inline": ["touch second base"]
    }
  ]
}

second.log

amazon-ebs output will be in this color.

==> amazon-ebs: Inspecting the source AMI...
==> amazon-ebs: Creating temporary security group for this instance...
==> amazon-ebs: Authorizing SSH access on the temporary security group...
==> amazon-ebs: Launching a source AWS instance...
    amazon-ebs: Instance ID: i-7dfc77b2
==> amazon-ebs: Waiting for instance (i-7dfc77b2) to become ready...
==> amazon-ebs: Waiting for SSH to become available...
==> amazon-ebs: Connected to SSH!
==> amazon-ebs: Provisioning with shell script: /var/folders/zg/dw2mgnh135l9976wfs62tsmh0000gp/T/packer-shell241255542
==> amazon-ebs: Stopping the source instance...
==> amazon-ebs: Waiting for the instance to stop...
==> amazon-ebs: Creating the AMI: packer-1415574159
    amazon-ebs: AMI: ami-db81eee1
==> amazon-ebs: Waiting for AMI to become ready...
==> amazon-ebs: Terminating the source AWS instance...
==> amazon-ebs: Deleting temporary security group...
Build 'amazon-ebs' finished.

==> Builds finished. The artifacts of successful builds are:
--> amazon-ebs: AMIs were created:

ap-southeast-2: ami-db81eee1