knife-exec - Online in the Cloud

PROGRAM:

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 Chef 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 Chef
server using the following methods:

┌───────────┬──────────────────────────────────┐
│Method │ Description │
├───────────┼──────────────────────────────────┤
│api.delete │ Use to delete an object from the │
│ │ Chef server. │
├───────────┼──────────────────────────────────┤
│api.get │ Use to get the details of an │
│ │ object on the Chef server. │
├───────────┼──────────────────────────────────┤
│api.post │ Use to add an object to the Chef │
│ │ server. │
├───────────┼──────────────────────────────────┤
│api.put │ Use to update an object on the │
│ │ Chef 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:

· api.method is the corresponding authentication method --- api.delete, api.get, api.post,
or api.put

· /endpoint is an endpoint in the Chef server API

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 subcommand has the following syntax:

$ knife exec SCRIPT (options)

Options

This subcommand has the following options:

-c CONFIG_FILE, --config CONFIG_FILE
The configuration file to use.

--chef-zero-port PORT
The port on which chef-zero will listen.

--[no-]color
Use to view colored output.

-d, --disable-editing
Use to prevent the $EDITOR from being opened and to accept data as-is.

--defaults
Use to have knife use the default value instead of asking a user to provide one.

-E CODE, --exec CODE
A string of code that will be executed.

-e EDITOR, --editor EDITOR
The $EDITOR that is used for all interactive commands.

--environment ENVIRONMENT
The name of the environment. When this option is added to a command, the command
will run only against the named environment.

-F FORMAT, --format FORMAT
The output format: summary (default), text, json, yaml, and pp.

-h, --help
Shows help for the command.

-k KEY, --key KEY
The private key that knife will use to sign requests made by the API client to the
Chef server.

-p PATH:PATH, --script-path PATH:PATH
A colon-separated path at which Ruby scripts are located.

--print-after
Use to show data after a destructive operation.

-s URL, --server-url URL
The URL for the Chef server.

-u USER, --user USER
The user name used by knife to sign requests made by the API client to the Chef
server. Authentication will fail if the user name does not match the private key.

-v, --version
The version of the chef-client.

-V, --verbose
Set for more verbose outputs. Use -VV for maximum verbosity.

-y, --yes
Use to respond to all confirmation prompts with "Yes". knife will not ask for
confirmation.

-z, --local-mode
Use to run the chef-client in local mode. This allows all commands that work
against the Chef server to also work against the local chef-repo.

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"}}

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