The knife tool in The Chef Development Kit is a great time saver. Here are some useful tricks which I have gleaned from various sources and put in one place for reference.

Find out when chef-client last updated a node

knife status

4 minutes ago, test2-inf-mongo-01, centos 6.6.
4 minutes ago, test-hyb-man-01, centos 6.6.
4 minutes ago, stg-hyb-sol-02, centos 6.6.
4 minutes ago, test2-node-api-02, centos 6.6.
4 minutes ago, test-inf-redis-02, centos 6.6.
4 minutes ago, test2-inf-mongo-03, centos 6.6.
3 minutes ago, stg-inf-redis-02, centos 6.6.
3 minutes ago, test2-hyb-solr-01, centos 6.6.
3 minutes ago, con-inf-db-01, centos 6.6.
2 minutes ago, uat-inf-mongo-01, centos 6.6.
1 minute  ago, stg-inf-mongo-02, centos 6.6.
1 minute  ago, stg-inf-gfs-01, centos 6.6.
0 minutes ago, uat-inf-db-06, centos 6.6.
0 minutes ago, solopt-node-mgmt-01, centos 6.7.
0 minutes ago, stg-inf-db-03, centos 6.6.

Find all nodes in an environment

knife search node chef_environment:<environment name>

Find all nodes which contain a role

knife search node role(s):<role name>

knife search node "role:web_frontend" -a hostname

You should use ‘roles’ plural when looking in the expanded run list.

Find all nodes which contain a recipe

# Looks for elkstack::default
knife search node "recipes:elk_stack"

#not the use of \:\ to escape the double colon
knife search node "recipe:windows\:\reboot_handler"

Find all non 64-bit nodes

knife search node "(NOT kernel_machine:x86_64)"

knife search node "name:*" -a chef_packages.chef.version

This returns the chef_packages.chef.version attribute from all nodes in the Chef Organisation.

Add a role to all nodes in an environment

# First, run it like this to run without saving the results back to the Chef server.
knife exec -E 'nodes.transform("chef_environment:uat") {|n| puts n.run_list << "role[hosts_file]" }'

knife exec -E 'nodes.transform("Chef_environment:uat") {|n| puts n.run_list << "role[hosts_file]"; n.save}'

To be on the safe side, run the command above without the n.save so results aren’t saved back to the Chef server. When you are sure about the command, run it with n.save to save the results back to the Chef server.

Add a role to all nodes in an Environment which does not contain the given role

knife exec -E 'nodes.find("chef_environment:uat") {|n| puts.n.run_list << "role[base]" unless n.run_list.include?("role[base]"); n.save }'

Remove a recipe from all nodes in an Environment

knife exec -E 'nodes.transform("chef_environment:uat") {|n| puts n.run_list.remove("recipe[chef-client::upgrade]""); n.save }'

Remove all nodes from a given role

knife exec -E 'nodes.find("role:web-frontend") {|n| n.run_list.remove("role(web-frontend)"); n.save }'

Set a node’s run_list back to a single item

knife exec -E 'nodes.transform("name:webserver-01.domain.com") {|n| n.run_list(["role[base]"])}'