How to use Packer Salt provisioner to create docker images?

Question

How to use Packer Salt provisioner to create docker images ?

here is my packer.json file. I will comment inline below

{
  "builders": [
    {
      "type": "docker",
      "image": "enonic/docker-salt-masterless-ubuntu",
      "export_path": "cassandra.tar" // Not sure what this is doing?
    }
  ],
  "provisioners": [
    {
      "type": "file",
      "source": "/srv/salt/cassandra", // This is where the cassandra directory is on my host machine which is ubuntu
      "destination": "/srv/salt/cassandra" // This is where I expect the cassandra directory on my host machine gets copied to inside a docker container
    },
    {
      "type": "salt-masterless",
      "local_state_tree": "/srv/salt/cassandra",
      "custom_state": "/srv/salt/cassandra/init.sls",
      "disable_sudo": true
    }
  ]
}

sudo docker build packer.json

I get the following error

Build 'docker' errored: Failed to upload to '/srv/salt/cassandra' in container: Error response from daemon: lstat /var/lib/docker/aufs/mnt/0c6a422400a073624a66b00580a6b9e5551e82a06495c46b1f840b38ca55699d/srv/salt: no such file or directory
. exit status 1.

==> Some builds didn't complete successfully and had errors:
--> docker: Failed to upload to '/srv/salt/cassandra' in container: Error response from daemon: lstat /var/lib/docker/aufs/mnt/0c6a422400a073624a66b00580a6b9e5551e82a06495c46b1f840b38ca55699d/srv/salt: no such file or directory

It would be great if I can get a simple working example on how to use salt state files from host machine and build a docker image using packer. My cassandra state files are same as https://github.com/salt-formulas/salt-formula-cassandra

My top.sls file looks like this

base:
  'client*-es-*':
    - roles-elasticsearch
  'client*-cassandra-*':
    - roles-cassandra


  'P@os:(Debian|Ubuntu) and P@roles:(elasticsearch|cassandra)':
    - match: compound
    - deb-common

  'roles:elasticsearch':
    - match: grain
    - disk-raid0-3volumes
    - disk-elasticsearch
    - elasticsearch
    - elasticsearch.cerebro
  'roles:cassandra':
    - match: grain
    - disk-raid0-3volumes
    - disk-cassandra
    - cassandra

I just want to build a docker container image only for cassandra but not for everything in my top.sls. so how do I do that?

Answer 1

I adjusted your example to be simpler and just install Apache 2.

The shell provisioner is just because I don't know salt and din't spend any time on howto do apt-get update.

First of all the base image already have salt installed so use skip_bootstrap. You shouldn't upload the state directory to the guest (Docker container) since this is done automatically, all this is in the documentation Packer - Salt Masterless. local_state_tree should point at the base of your salt state tree i.g. /srv/salt in you case.

A working example:

Tree

.
├── salt
│   ├── apache
│   │   └── init.sls
│   └── top.sls
└── template.json

Template.json

{
  "builders": [
    {
      "type": "docker",
      "image": "enonic/docker-salt-masterless-ubuntu",
      "export_path": "apache2.tar"
    }
  ],
  "provisioners": [
    {
      "type": "shell",
      "inline": [
        "apt-get update"
      ]
    },
    {
      "type": "salt-masterless",
      "local_state_tree": "salt",
      "skip_bootstrap": true,
      "disable_sudo": true
    }
  ]
}

top.sls

base:
  '*':
    - apache

apache/init.sls

apache2:
  pkg.installed: []
  service.running:
    - require:
      - pkg: apache2