Dynamic Chef Solo (DCS)

Dynamic Chef Solo provides an easier to produce the JSON attributes used by Chef Solo.

DSC sets up a series of JSON-like files that are combined at build time to a JSON file suitable for use by Chef Solo. By building in concepts like environment, datacenter, purpose, and individual node attributes we can produce a richer and easier to use configuration system.

Installation

sudo pip install dcs

How it works

DCS combines attributes from multiple JSON files into a single JSON file which can be used by Chef Solo.

Attributes are combined (merged) in the following order:

1. product (directory: products/)
2. environment (directory: environments/)
3. region (directory: regions/)
4. data center (directory: datacenters/)
5. purpose (directory: purposes/)

An attribute which is treated specially is run_list. This attribute needs to be a list and when merging multiple files with this attributes, lists are concatenated together. For an example, see the "Example" section bellow.

Another directory which is special is nodes-info directory. This directory contains JSON files which contain server information (e.g. information obtained by ohai / facter). File names in this directory must match the server name. Attributes from this file are stored in the info attribute in the generated JSON file.

Main attributes are inferred from the node name which means the name needs to be in the following format:

^(?P<datacenter>\w+)(?P<datacenter_number>\d+)-(?P<product>\w+)-(?P<environment>\w+)-(?P<purpose>\w+)(?P<purpose_number>\d+)(\..*){0,1}$

Example attribute values using the name dfw1-maas-stage-api0 with a node file stored in nodes/dfw1-maas-stage-api0.k1k.me.dyp:

• region: dfw (file: regions/dfw.dyp)
• data center: dfw1 (file: datacenters/dfw1.dyp)
• product: maas (file: products/maas.dyp)
• environment: stage (file: environments/stage.dyp)
• purpose: api (file: purposes/api.dyp)

Running it

bin/dcs-builder.py [--validate] --source=<path to the directory with attributes files> --output=<output directory>

Example 1

For a machine with name ord1-maas-prod-api0, with the following files:

• environments/prod.dyp:

{
    "environment": "production",
    "auth_servers": [
        "https://identity.api.rackspacecloud.com/"
    ],
    "run_list": [
        "role[ele-base]"
    ]
}

• regions/ord1.dyp:

{
    "region": "ord1"
}

• purposes/api.dyp:

{
    "mail_relay": "smtp.sendgrid.com",
    "run_list": [
        "recipe[ele-base::api]"
    ]
}

• nodes/ord1-maas-prod-api0.k1k.me.dyp:

{
    "is_active": true
}

• nodes-info/ord1-maas-prod-api0.k1k.me.dyp

{
    "interfaces": {
        "eth1": {
            "ipv4": "10.180.1.1",
            "ipv6": null
        },
        "eth0": {
            "ipv4": "198.101.200.200",
            "ipv6": null
        }
    }
}

These sources would be compiled into a single ord1-maas-prod-api0.json suitable for use by chef-solo:

{
    "is_active": true,
    "mail_relay": "smtp.sendgrid.com",
    "region": "ord1",
    "environment": "production",
    "auth_servers": [
        "https://identity.api.rackspacecloud.com/"
    ],
    "run_list": [
        "role[ele-base]"
    ],
    "info": {
        "interfaces": {
            "eth0": {
                "ipv4": "198.101.220.207",
                "ipv6": null
            },
            "eth1": {
                "ipv4": "10.180.161.14",
                "ipv6": null
            }
        }
    }
}

Example 2

Another example can be found here.

To generate the output files, you can run the following command:

dcs-builder.py [--validate] --source=examples/example-1/ --output=out