NAME¶

knife-exec - The man page for the knife exec subcommand. The knife exec subcommand uses the Knife configuration file to execute Ruby scripts in the context of a fully configured chef-client. This subcommand is most often used to run scripts that will only access server one time (or otherwise very infrequently). Use this subcommand any time that an operation does not warrant full usage of the Knife subcommand library. Authenticated API Requests The knife exec subcommand can be used to make authenticated API requests to the server using the following methods:

Method	Description
api.delete	Use to delete an object from the server.
api.get	Use to get the details of an object on the server.
api.post	Use to add an object to the server.
api.put	Use to update an object on the server.

These methods are used with the -E option, which executes that string locally on the workstation using chef-shell. These methods have the following syntax:

$ knife exec -E 'api.method(/endpoint)'

where:
For example, to get the data for a node named "Example_Node":

$ knife exec -E 'puts api.get("/nodes/Example_Node")'

and to ensure that the output is visible in the console, add the puts in front of the API authorization request:

$ knife exec -E 'puts api.get("/nodes/Example_Node")'

where puts is the shorter version of the $stdout.puts predefined variable in Ruby. The following example shows how to add a client named "IBM305RAMAC" and the /clients endpoint, and then return the private key for that user in the console:

$ client_desc = {
    "name"  => "IBM305RAMAC",
    "admin" => false
  }

  new_client = api.post("/clients", client_desc)
  puts new_client["private_key"]

Syntax This argument has the following syntax:

$ knife exec SCRIPT (options)

Options This subcommand has the following options:
Examples There are three ways to use knife exec to run Ruby script files. For example:

$ knife exec /path/to/script_file

Or:

$ knife exec -E 'RUBY CODE'

Or:

$ knife exec
RUBY CODE
^D

To check the status of Knife using a Ruby script named "status.rb" (which looks like):

printf "%-5s %-12s %-8s %s\n", "Check In", "Name", "Ruby", "Recipes"
nodes.all do |n|
   checkin = Time.at(n['ohai_time']).strftime("%F %R")
   rubyver = n['languages']['ruby']['version']
   recipes = n.run_list.expand(_default).recipes.join(", ")
   printf "%-20s %-12s %-8s %s\n", checkin, n.name, rubyver, recipes
end

and is located in a directory named "scripts", enter:

$ knife exec scripts/status.rb

To show the available free memory for all nodes, enter:

$ knife exec -E 'nodes.all {|n| puts "#{n.name} has #{n.memory.total} free memory"}'

To list all of the available search indexes, enter:

$ knife exec -E 'puts api.get("search").keys'

To query a node for multiple attributes using a Ruby script named search_attributes.rb (which looks like):

% cat scripts/search_attributes.rb
query = ARGV[2]
attributes = ARGV[3].split(",")
puts "Your query: #{query}"
puts "Your attributes: #{attributes.join(" ")}"
results = {}
search(:node, query) do |n|
   results[n.name] = {}
   attributes.each {|a| results[n.name][a] = n[a]}
end

puts results
exit 0

enter:

% knife exec scripts/search_attributes.rb "hostname:test_system" ipaddress,fqdn

to return something like:

Your query: hostname:test_system
Your attributes: ipaddress fqdn
{"test_system.example.com"=>{"ipaddress"=>"10.1.1.200", "fqdn"=>"test_system.example.com"}}

AUTHOR¶

Chef