puppet-tell

Tell external parties about changes to resources.

Sometimes it's quite handy to be able to know when things on your systems change, in real-time. A good example is upgrading your Linux system kernel. Typically you don't want puppet to blindly reboot your machine to get the new kernel running, but you do want to know that the system has a kernel update installed, and waiting to be rebooted to.

Depending on your implementation and how your organization works, you will have different requirements on how to handle these types of events. If you are managing some test systems, or some development systems, or just a local sandbox of machines, maybe you want them to automatically restart themselves. In contrast, maybe you are managing production systems, and you want just a notification of your resource change event.

How it works

This module currently provides two ways of externalizing puppet resource changes:

• By email
• Using a web hook (way more interesting)

It will expose any resource change by sending the resource data to the external party. The resource data is simply the pson data directly from the changed resource, encoded in a format specified by the user. This is collected by looking it up in the relationship graph from the running catalog.

This module follows almost the same logic as the 'exec' resource type utilizing 'refreshonly'. It is implemented slightly different, where 'false' is the default value (since this module isn't very useful if you are just triggering it from Class[main] all the time). You can still specify refreshonly => false, even though there probably isn't a valid use case for it, at least not yet...

Web hooks

While using web hooks, the default behavior is to simply make a GET request to the URL you specify in the 'dest' parameter with no request parameters. If you specify one of 'get' or 'post', a respective query will be sent to the url specified by 'dest', and additionally, the resource that triggered the tell resource will be encoded and sent by the parameter name specified. See below for a better explanation.

Example

In this example, the vim-enhanced package changes to 'latest' from 'absent'. The example results would be POST'ed to a web service via HTTP if you are using a web hook, or an email would have been sent through the default system relay if you are 'telling' an email address about the resource change.

Puppet DSL:

Package {
    notify => [
        Tell['package_updated_email'],
        Tell['package_updated_webhook']
    ]
}

package { "vim-enhanced": ensure => "latest" }

tell {
    'package_updated_email':
        dest => '[email protected]';

    'package_updated_webhook':
        dest => 'http://rest.example.com/v1/package-update-notifications',
        post => 'packagedata';
}

When you run it, you will see something like this:

/Stage[main]//Package[vim-enhanced]/ensure: created
/Stage[main]//Tell[package_updated_webhook]: Triggered 'refresh' from 1 events
/Stage[main]//Tell[package_updated_email]/returns: Successfully told [email protected]
/Stage[main]//Tell[package_updated_email]: Triggered 'refresh' from 1 events
Finished catalog run in 8.26 seconds

Results in the default YAML format:

---
  - exported: false
    title: vim-enhanced
    parameters:
      !ruby/sym configfiles: !ruby/sym keep
      !ruby/sym ensure: "7.2.411-1.8.el6"
      !ruby/sym provider: !ruby/sym yum
      !ruby/sym loglevel: !ruby/sym notice
      !ruby/sym notify:
        - Tell[package_updated]
    type: Package
    tags:
      - package
      - vim-enhanced
      - class
  - exported: false
    title: Main
    parameters:
      !ruby/sym name: admissible_Class[Main]
      !ruby/sym loglevel: !ruby/sym notice
    type: Admissible_class
    tags:
      - admissible_class
      - main

Results in JSON format (requires 'json' rubygem)

[
  {
    "title": "vim-enhanced",
    "type": "Package",
    "parameters": {
      "ensure": "7.2.411-1.8.el6",
      "configfiles": "keep",
      "provider": "yum",
      "loglevel": "notice",
      "notify": [
        "Tell[package_updated]"
      ]
    },
    "exported": false,
    "tags": [
      "package",
      "vim-enhanced",
      "class"
    ]
  },
  {
    "title": "Main",
    "type": "Admissible_class",
    "parameters": {
      "name": "admissible_Class[Main]",
      "loglevel": "notice"
    },
    "exported": false,
    "tags": [
      "admissible_class",
      "main"
    ]
  }
]

In the near future

• Further extending webhooks support to support remaining HTTP methods and HTTPS
• SNMP support?