launchd Resource

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Use the launchd resource to manage system-wide services (daemons) and per-user services (agents) on the macOS platform.

New in Chef Infra Client 12.8.

Syntax

The full syntax for all of the properties that are available to the launchd resource is:

launchd 'name' do
  abandon_process_group              true, false
  associated_bundle_identifiers      Array
  backup                             Integer, false
  cookbook                           String
  debug                              true, false
  disabled                           true, false # default value: false
  enable_globbing                    true, false
  enable_transactions                true, false
  environment_variables              Hash
  exit_timeout                       Integer
  group                              String, Integer
  hard_resource_limits               Hash
  inetd_compatibility                Hash
  init_groups                        true, false
  keep_alive                         true, false, Hash
  label                              String # default value: 'name' unless specified
  launch_events                      Hash
  launch_only_once                   true, false
  ld_group                           String
  limit_load_from_hosts              Array
  limit_load_to_hosts                Array
  limit_load_to_session_type         Array, String
  low_priority_io                    true, false
  mach_services                      Hash
  mode                               String, Integer
  nice                               Integer
  on_demand                          true, false
  owner                              String, Integer
  path                               String
  plist_hash                         Hash
  process_type                       String
  program                            String
  program_arguments                  Array
  queue_directories                  Array
  root_directory                     String
  run_at_load                        true, false
  session_type                       String
  sockets                            Hash
  soft_resource_limits               Array
  source                             String
  standard_error_path                String
  standard_in_path                   String
  standard_out_path                  String
  start_calendar_interval            Hash, Array
  start_interval                     Integer
  start_on_mount                     true, false
  throttle_interval                  Integer
  time_out                           Integer
  type                               String # default value: "daemon"
  username                           String
  wait_for_debugger                  true, false
  watch_paths                        Array
  working_directory                  String
  action                             Symbol # defaults to :create if not specified
end

where:

• launchd is the resource.
• name is the name given to the resource block.
• action identifies which steps Chef Infra Client will take to bring the node into the desired state.
• abandon_process_group, associated_bundle_identifiers, backup, cookbook, debug, disabled, enable_globbing, enable_transactions, environment_variables, exit_timeout, group, hard_resource_limits, inetd_compatibility, init_groups, keep_alive, label, launch_events, launch_only_once, ld_group, limit_load_from_hosts, limit_load_to_hosts, limit_load_to_session_type, low_priority_io, mach_services, mode, nice, on_demand, owner, path, plist_hash, process_type, program, program_arguments, queue_directories, root_directory, run_at_load, session_type, sockets, soft_resource_limits, source, standard_error_path, standard_in_path, standard_out_path, start_calendar_interval, start_interval, start_on_mount, throttle_interval, time_out, type, username, wait_for_debugger, watch_paths, and working_directory are the properties available to this resource.

Actions

The launchd resource has the following actions:

:create

Create a launchd property list. (default)

:create_if_missing

Create a launchd property list, if it does not already exist.

:delete

Delete a launchd property list. This will unload a daemon or agent, if loaded.

:disable

Disable a launchd property list.

:enable

Create a launchd property list, and then ensure that it is enabled. If a launchd property list already exists, but does not match, updates the property list to match, and then restarts the daemon or agent.

:nothing

This resource block doesn’t act unless notified by another resource to take action. Once notified, this resource block either runs immediately or is queued up to run at the end of a Chef Infra Client run.

:restart

Restart a launchd managed daemon or agent.

Properties

The launchd resource has the following properties:

abandon_process_group

Ruby Type: true, false

If a job dies, all remaining processes with the same process ID may be kept running. Set to true to kill all remaining processes.

associated_bundle_identifiers

Ruby Type: Array

This optional key indicates which bundles the Login Items Added by Apps panel associates with the helper executable.

backup

Ruby Type: Integer, false

The number of backups to be kept in /var/chef/backup. Set to false to prevent backups from being kept.

cookbook

Ruby Type: String

The name of the cookbook in which the source files are located.

debug

Ruby Type: true, false

Sets the log mask to LOG_DEBUG for this job.

disabled

Ruby Type: true, false | Default Value: false

Hints to launchctl to not submit this job to launchd.

enable_globbing

Ruby Type: true, false

Update program arguments before invocation.

enable_transactions

Ruby Type: true, false

Track in-progress transactions; if none, then send the SIGKILL signal.

environment_variables

Ruby Type: Hash

Additional environment variables to set before running a job.

exit_timeout

Ruby Type: Integer

The amount of time (in seconds) launchd waits before sending a SIGKILL signal.

group

Ruby Type: String, Integer

When launchd is run as the root user, this is the corresponding group to run the job as. If the username property is specified and this property is not, this value is set to the default group for the user.

hard_resource_limits

Ruby Type: Hash

A Hash of resource limits to be imposed on a job.

inetd_compatibility

Ruby Type: Hash

Specifies if a daemon expects to be run as if it were launched from inetd. Set to wait => true to pass standard input, output, and error file descriptors. Set to wait => false to call the accept system call on behalf of the job, and then pass standard input, output, and error file descriptors.

init_groups

Ruby Type: true, false

Specify if initgroups is called before running a job.

keep_alive

Ruby Type: true, false, Hash

Keep a job running continuously (true) or allow demand and conditions on the node to determine if the job keeps running (false).

New in Chef Client 12.14

label

Ruby Type: String | Default Value: The resource block's name

The unique identifier for the job.

launch_events

Ruby Type: Hash

Specify higher-level event types to be used as launch-on-demand event sources.

New in Chef Infra Client 15.1

launch_only_once

Ruby Type: true, false

Specify if a job can be run only one time. Set this value to true if a job cannot be restarted without a full machine reboot.

ld_group

Ruby Type: String

The group name.

limit_load_from_hosts

Ruby Type: Array

An array of hosts to which this configuration file does not apply, i.e. ‘apply this configuration file to all hosts not specified in this array’.

limit_load_to_hosts

Ruby Type: Array

An array of hosts to which this configuration file applies.

limit_load_to_session_type

Ruby Type: Array, String

The session type(s) to which this configuration file applies.

low_priority_io

Ruby Type: true, false

Specify if the kernel on the node should consider this daemon to be low priority during file system I/O.

mach_services

Ruby Type: Hash

Specify services to be registered with the bootstrap subsystem.

mode

Ruby Type: String, Integer

A quoted 3-5 character string that defines the octal mode. For example: ‘755’, ‘0755’, or 00755.

nice

Ruby Type: Integer

The program scheduling priority value in the range -20 to 19.

on_demand

Ruby Type: true, false

Keep a job alive. Only applies to macOS version 10.4 (and earlier); use keep_alive instead for newer versions.

owner

Ruby Type: String, Integer

A string or ID that identifies the group owner by user name, including fully qualified user names such as domain_user or user@domain. If this value is not specified, existing owners remain unchanged and new owner assignments use the current user (when necessary).

path

Ruby Type: String

The path to the directory. Using a fully qualified path is recommended, but is not always required.

plist_hash

Ruby Type: Hash

A Hash of key value pairs used to create the launchd property list.

New in Chef Client 12.19

process_type

Ruby Type: String

The intended purpose of the job: Adaptive, Background, Interactive, or Standard.

program

Ruby Type: String

The first argument of execvp, typically the file name associated with the file to be executed. This value must be specified if program_arguments is not specified, and vice-versa.

program_arguments

Ruby Type: Array

The second argument of execvp. If program is not specified, this property must be specified and will be handled as if it were the first argument.

queue_directories

Ruby Type: Array

An array of non-empty directories which, if any are modified, will cause a job to be started.

root_directory

Ruby Type: String

chroot to this directory, and then run the job.

run_at_load

Ruby Type: true, false

Launch a job once (at the time it is loaded).

session_type

Ruby Type: String

The type of launchd plist to be created. Possible values: system (default) or user.

sockets

Ruby Type: Hash

A Hash of on-demand sockets that notify launchd when a job should be run.

soft_resource_limits

Ruby Type: Array

A Hash of resource limits to be imposed on a job.

source

Ruby Type: String

The path to the launchd property list.

standard_error_path

Ruby Type: String

The file to which standard error (stderr) is sent.

standard_in_path

Ruby Type: String

The file to which standard input (stdin) is sent.

standard_out_path

Ruby Type: String

The file to which standard output (stdout) is sent.

start_calendar_interval

Ruby Type: Hash, Array

A Hash (similar to crontab) or an Array that defines the calendar frequency at which a job is started. For example: { Minute => "0", Hour => "20", Day => "*", Weekday => "1-5", Month => "*" } will run a job at 8:00 PM every day, Monday through Friday, every month of the year.

start_interval

Ruby Type: Integer

The frequency (in seconds) at which a job is started.

start_on_mount

Ruby Type: true, false

Start a job every time a file system is mounted.

throttle_interval

Ruby Type: Integer

The frequency (in seconds) at which jobs are allowed to spawn.

time_out

Ruby Type: Integer

The amount of time (in seconds) a job may be idle before it times out. If no value is specified, the default timeout value for launchd will be used.

type

Ruby Type: String | Default Value: daemon

The type of resource. Possible values: daemon (default), agent.

username

Ruby Type: String

When launchd is run as the root user, the user to run the job as.

wait_for_debugger

Ruby Type: true, false

Specify if launchd has a job wait for a debugger to attach before executing code.

watch_paths

Ruby Type: Array

An array of paths which, if any are modified, will cause a job to be started.

working_directory

Ruby Type: String

chdir to this directory, and then run the job.

Common Resource Functionality

Chef resources include common properties, notifications, and resource guards.

Common Properties

The following properties are common to every resource:

compile_time

Ruby Type: true, false | Default Value: false

Control the phase during which the resource is run on the node. Set to true to run while the resource collection is being built (the compile phase). Set to false to run while Chef Infra Client is configuring the node (the converge phase).

ignore_failure

Ruby Type: true, false, :quiet | Default Value: false

Continue running a recipe if a resource fails for any reason. :quiet won’t display the full stack trace and the recipe will continue to run if a resource fails.

retries

Ruby Type: Integer | Default Value: 0

The number of attempts to catch exceptions and retry the resource.

retry_delay

Ruby Type: Integer | Default Value: 2

The delay in seconds between retry attempts.

sensitive

Ruby Type: true, false | Default Value: false

Ensure that sensitive resource data isn’t logged by Chef Infra Client.

Notifications

notifies

Ruby Type: Symbol, 'Chef::Resource[String]'

A resource may notify another resource to take action when its state changes. Specify a 'resource[name]', the :action that resource should take, and then the :timer for that action. A resource may notify more than one resource; use a notifies statement for each resource to be notified.

If the referenced resource doesn’t exist, an error is raised. In contrast, subscribes won’t fail if the source resource isn’t found.

A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:

:before

Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.

:delayed

Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.

:immediate, :immediately

Specifies that a notification should be run immediately, for each resource notified.

The syntax for notifies is:

notifies :action, 'resource[name]', :timer

subscribes

Ruby Type: Symbol, 'Chef::Resource[String]'

A resource may listen to another resource, and then take action if the state of the resource being listened to changes. Specify a 'resource[name]', the :action to be taken, and then the :timer for that action.

Note that subscribes doesn’t apply the specified action to the resource that it listens to - for example:

file '/etc/nginx/ssl/example.crt' do
  mode '0600'
  owner 'root'
end

service 'nginx' do
  subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately
end

In this case the subscribes property reloads the nginx service whenever its certificate file, located under /etc/nginx/ssl/example.crt, is updated. subscribes doesn’t make any changes to the certificate file itself, it merely listens for a change to the file, and executes the :reload action for its resource (in this example nginx) when a change is detected.

If the other resource doesn’t exist, the subscription won’t raise an error. Contrast this with the stricter semantics of notifies, which will raise an error if the other resource doesn’t exist.

A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:

:before

Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.

:delayed

Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.

:immediate, :immediately

Specifies that a notification should be run immediately, for each resource notified.

The syntax for subscribes is:

subscribes :action, 'resource[name]', :timer

Guards

A guard property can be used to evaluate the state of a node during the execution phase of a Chef Infra Client run. Based on the results of this evaluation, a guard property is then used to tell Chef Infra Client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:

• A string is executed as a shell command. If the command returns 0, the guard is applied. If the command returns any other value, then the guard property isn’t applied. String guards in a powershell_script run Windows PowerShell commands and may return true in addition to 0.
• A block is executed as Ruby code that must return either true or false. If the block returns true, the guard property is applied. If the block returns false, the guard property isn’t applied.

A guard property is useful for ensuring that a resource is idempotent by allowing that resource to test for the desired state as it’s being executed, and then if the desired state is present, for Chef Infra Client to don’thing.

The following properties can be used to define a guard that’s evaluated during the execution phase of a Chef Infra Client run:

not_if

Prevent a resource from executing when the condition returns true.

only_if

Allow a resource to execute only if the condition returns true.

Examples

The following examples demonstrate various approaches for using the launchd resource in recipes:

Create a Launch Daemon from a cookbook file

launchd 'com.chef.every15' do
  source 'com.chef.every15.plist'
end

Create a Launch Daemon using keys

launchd 'call.mom.weekly' do
  program '/Library/scripts/call_mom.sh'
  start_calendar_interval 'Weekday' => 7, 'Hourly' => 10
  time_out 300
end

Remove a Launch Daemon

launchd 'com.chef.every15' do
  action :delete
end