search_helpers

search_helpers is a chef library cookbook designed to streamline common tasks in
Chef that require search.

[Changelog](CHANGELOG.md)

See CHANGELOG.md for additional information about changes to this stack over time.

Supported Platforms

• Ubuntu 12.04
• CentOS 6.5

Usage

Place a dependency on the search_helpers cookbook in your cookbook's metadata.rb

depends 'search_helpers'

Then, in a recipe:

discovery 'my_cookbook_mysql_master' do
  tags ['mysql', 'master']
  action :search
end

Resource

discovery

Provides a rudimentary discovery mechanism on top of chef search, based on a tag
model. Note that while the default implementation relies on underlying Chef
tags, future implementations might not necessarily do so.

The discovery resource and provider provides generic actions for applying tags
to any Chef node, as well as enumerating other Chef nodes with a given tag or
running a provided block on all nodes that have specific tags.

Parameters

• tags - List of tags to apply or search for.

• block

The block attribute, by default, is nil. This means
node.run_state["discovery_#{new_resource.name}"] will contain an array
of nodes returned from the search. You may also pass a block to data and that
block will be executed for each node returned from the search, in addition to
the node.run_state being set.

If you return a value from your block (instead of nil),
node.run_state["discovery_#{new_resource.name}"] will be populated with an
array of objects returned from the block.

Actions

• :search - Default action, Find a node with a particular array of tags
• :add - Apply tags to a node
• :remove: Remove tags from a node

Examples

Search and store the result in a run_state attribute :

discovery 'my_cookbook_mysql_master' do
  tags ['mysql', 'master']
  action :search
end
found_master = node.run_state['discovery_my_cookbook_mysql_master'].first
if found_master
  Chef::Log.info("Found mysql master #{found_master}")
else
  Chef::Log.info('No mysql master was found')
end

Use the search result in a block to find nodes IPs :

discovery 'find a mysql master' do
  tags ['master', 'mysql']
  block do |node|
    node_ip = best_ip_for(node)
    Chef::Log.warn("#{node.name} was found as a mysql master at #{node_ip}")
    node_ip
  end
  action :search
end

Apply tags to a node

discovery 'add mysql master tag' do
  tags ['master', 'mysql']
  action :add
end

Remove tags from a node

discovery 'no longer consider this node a mysql master' do
  tags ['mysql', 'master']
  action :remove
end

Contributing

1. Fork the repository on Github
2. Create a named feature branch (i.e. add-new-recipe)
3. Write your change
4. Write tests for your change (if applicable)
5. Run the tests, ensuring they all pass
6. Submit a Pull Request

Authors

Author:: Rackspace (devops-chef@rackspace.com)

License

# Copyright 2015, Rackspace Hosting
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#