Search

Search is used to run a query on chef-server.
To search for nodes, roles, environment and data bags.
Search patterns include exact, wildcards and range.
Search can be included within recipe or using knife CLI.

Replacing myhaproxy recipe

Instead of adding the additional web servers manually to the list of haproxy, we can use search inside recipe to perform that.
Now we can change the default recipe as follows
Path: sysfoo/cookbooks/myhaproxy/recipes/default.rb

all_web_nodes = search("node", "role:app")

members = [ ]

all_web_nodes.each do | web_node |

     member = {
        'hostname' => web_node['hostname'],
        'ipaddress' => web_node['ipaddress'],
        'port' => 8080,
        'ssl_port' => 8080
    }

  members.push(member)
end

node.default['haproxy']['members'] = members

node.default['haproxy']['incoming_port'] = 8080

include_recipe 'haproxy::default'

Now before uploading this to chef server we will change the version of cookbook by adding the version in metadata.
Change the version in sysfoo/cookbooks/myhaproxy/metadata.rb from 0.1.0 to 0.2.0.
Upload the myhaproxy cookbook.

Verifying Search Functionality

Now bootstrap node3 as web server using the role app.
Before bootstrap watch the haproxy.cfg file in node4(Load Balancer), which will be getting updated for every 60 seconds defined by chef-client process.

watch -n 1 tail /etc/haproxy/haproxy.cfg

Now bootstrap node3 from workstation,

knife bootstrap node3 -x devops --sudo -N "app3" -r "role[app]"

After a minute we can see the entry of new web-server node3 added to the load balancer configuration file.