wiki:CloudPlugin

Version 30 (modified by robguttman, 4 years ago) (diff)

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Orchestrates AWS cloud resources using boto and pychef

This fairly new plugin is now being used at juju.com. I welcome others to try it out and submit tickets for bugs and new features. - robguttman, 7 Feb 2011

Description

This plugin is meant to fill the coordination gap between AWS and Chef, especially:

  • Launch an ec2 instance and apply one or more chef roles
  • Terminate ec2 instances and delete its chef node (and client)

There are additional features and quite possibly more to come, but my intention is to keep the scope down to what's needed to orchestrate between AWS and Chef (and not re-implement either the AWS Management Console or the Chef Server webui).

This plugin is highly configurable but is opinionated in some ways. Some of these opinions could be relaxed (submit a ticket!) but they currently are:

  • Uses knife bootstrap to bootstrap instances - and so your instances' OS must support this method.
  • Assumes the same credentials and security (e.g., keypair) are used for all instances.
  • Allows one or more roles (but no recipes) to define a node's run_list.

This plugin relies heavily upon boto and pychef. Special thanks to coderanger for his work and responsiveness on pychef.

Configuration

  1. Install the plugin (after downloading and unzipping):
    cd cloudplugin/0.12
    sudo python setup.py bdist_egg
    sudo cp dist/TracCloud*.egg /your/trac/location/plugins/
    

See TracPlugins for more installation details and options. You'll likely need to restart Trac's web server after installation.

  1. Enable the plugin in trac.ini:
    [components]
    cloud.* = enabled
    

You can alternatively use the Trac Web Admin GUI to enable any or all rules.

  1. Ensure Trac's web server can support long-running requests. Launching an ec2 instance can take several minutes which may be longer than your web server's timeout depending on how you setup Trac. For example, for an apache2 and fcgi setup, you should add the following directive to your Trac's apache conf:
    FcgidIOTimeout 900
    
  1. Configure the main trac.ini section. A minimal configuration would look like this:
    [cloud]
    aws_key = <aws-access-key>
    aws_secret = <aws-secret-key>
    aws_keypair = <ec2-keypair-name>
    aws_keypair_pem = /path/to/keypair.pem
    aws_username = <ec2-username>
    chef_base_path = /path/to/.chef
    

AWS access configuration

The aws_* options (see example above) are for your AWS credentials and security information. For more info, see here and here.

Chef access configuration

Your Trac server must already have been configured using knife configure. For more info see here. Set the chef_base_path option to the standard chef directory that contains the knife.rb and client pem files needed to connect with the chef server. Common settings for this option are /etc/chef or /home/<username>/.chef. Be sure that the validation.pem file is located where the knife.rb file says it should be.

Bugs/Feature Requests

Existing bugs and feature requests for CloudPlugin are here.

If you have any issues, create a new ticket.

Download

Download the zipped source from here.

Source

You can check out CloudPlugin from here using Subversion, or browse the source with Trac.

Examples

This plugin is designed to support multiple AWS resource types, the most notable being ec2 instances.

Instances

The configuration for the ec2 instance resource type has reasonable defaults all of which can be overridden in its own trac.ini section:

[cloud.instance]
...

The different configuration options are broken out below.

Labels and such

[cloud.instance]
title = Instances
order = 1
label = Instance
description = AWS EC2 instances.

The title and order options are used for contextual navigation - see screenshot above. The order should start with 1. If order is set to an empty string then the resource will not be shown in the contextual menu (but is still accessible by its url). The label value is displayed in various buttons and forms for the name of a single resource item. The description option is displayed in the grid view - see screenshot above - much like a Trac report description.

Field Definitions

The fields shown in each view can be configured. Fields are first defined much like Trac custom fields but prefixed with field.:

[cloud.instance]
 ..
field.name = text
field.name.label = Name
field.name.handler = NameHandler
field.run_list = multiselect
field.run_list.label = Roles
field.run_list.databag = roles  # special token
field.run_list.handler = RunListHandler
field.ec2.placement_availability_zone = select
field.ec2.placement_availability_zone.label = Availability Zone
field.ec2.placement_availability_zone.options = No preference|us-east-1a|us-east-1b|us-east-1c|us-east-1d
 .. many more fields ..

Each field.* option must map exactly to its chef attribute name. For example, ec2.placement_availability_zone above maps to the ec2 attribute namespace and the placement_availability_zone attribute within that namespace in chef. It's defined as a select field with a display label and several options separated by a pipe (|) just like Trac custom fields. There are some important differences to Trac custom fields, however:

  • A field can define a data bag instead of options
  • A field can define a "field handler"
Data Bags for options

You may prefer to define a select (or multiselect) field's options by using a chef data bag instead of listing them in the trac.ini file. For example, a field defined like this:

[cloud.instance]
 ..
field.ec2.ami_id = select
field.ec2.ami_id.label = Image ID
field.ec2.ami_id.databag = ec2_ami_id

will query chef for and use the ec2_ami_id data bag items. The individual data bag items should be formatted like this:

{
  "id": "ami-xxxxxxxx",
  "value": "ami-xxxxxxxx",
  "name": "ami-xxxxxxxx (64-bit)",
  "order": 1
}

The name will be used as the option's displayed name and the value will be used as the option's value. If an order field is provided, it will be used to order the options accordingly (much like custom field ordering).

Specifying roles as a data bag has a special meaning (see the run_list field example above) - chef will be queried for the list of roles instead of a data bag.

Field handlers

A field handler converts a raw chef attribute value into something more human-readable and vice-versa. For example, the RunListHandler defined above for the run_list field extracts roles from a chef node's run_list and displays them in an easy-to-read way. It also converts data the other direction - i.e., it converts the list of roles from a web form into the correct format to set the node's run_list.

Other field handler examples include displaying a url to a web site at a specific port, converting epoch's to dates and times, etc. See handlers.py for the full list of provided field handlers and defaults.py for examples of which fields they're used for by default

Views

In addition to field definitions, you can define which fields should be viewed in which views, their order, and whether or not a field should be read-only in that view. Example:

[cloud.instance]
 ..
crud_view = name, ec2.instance_type, ohai_time, ..
crud_new = roles, created_by, created_at, ..
crud_edit = roles, created_by, created_at*, ..

grid_columns = name, ec2.instance_type, ohai_time, ..
grid_sort = ohai_time
grid_asc = 0

The crud_view, crud_new, crud_edit, and grid_columns options are lists of field names in the order to be displayed in their respective views. ("crud" stands for "create, read, update, delete".) An asterisk (*) appended to a field name (only applicable for crud_new and crud_edit) indicates that the field should be read-only in that view. All fields in the crud_new and crud_edit views will be used to set or update the chef resource item.

The grid_sort and grid_asc are for default sorting in the grid view.

Recent Changes

[14004] by rjollos on 2014-07-12 20:27:48
Correct license keyword argument in setup.py. Refs #11832.
[13996] by rjollos on 2014-06-25 02:56:32
Fixed author in COPYING file. Refs #11832.
[13994] by rjollos on 2014-06-25 02:51:36
Changed to 3-Clause BSD license with permission of author. Refs #11832.

Author/Contributors

Author: robguttman
Maintainer: robguttman
Contributors:

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