generic_base.json

{
    "variables": {
      "aws_access_key": "{{env `AWS_ACCESS_KEY_ID`}}",
      "aws_secret_key": "{{env `AWS_SECRET_ACCESS_KEY`}}",
      "region": "{{env `AWS_DEFAULT_REGION`}}"
    },
    "builders": [
      {
        "type": "amazon-ebs",
        "ami_name": "packer-ubuntu-base-{{timestamp}}",
        "instance_type": "c5n.large",
        "access_key": "{{user `aws_access_key`}}",
        "secret_key": "{{user `aws_secret_key`}}",
        "region": "{{user `region`}}",
        "source_ami_filter": {
          "filters": {
            "virtualization-type": "hvm",
            "name": "ubuntu/images/*ubuntu-bionic-18.04-amd64-server-*",
            "root-device-type": "ebs"
          },
          "owners": ["099720109477"],
          "most_recent": true
        },
        "ssh_username": "ubuntu"
      }
    ],
    "provisioners": [
      {
        "type": "shell",
        "script": "./generic_base/base_setup.sh"
      },
      {
        "type": "shell",
        "script": "./generic_base/zsh_setup.sh"
      }
    ],
    "post-processors": [
      {
        "type": "manifest",
        "output": "manifest.json",
        "strip_path": true
      },
      {
        "type": "shell-local",
        "scripts": ["./common/post-process.sh"]
      }
    ]
  }