log

Use the log resource to create log entries. The log resource behaves like any other resource: built into the resource collection during the compile phase, and then run during the execution phase. (To create a log entry that is not built into the resource collection, use Chef::Log instead of the log resource.)

Note

By default, every log resource that executes will count as an updated resource in the updated resource count at the end of a Chef run. You can disable this behavior by adding count_log_resource_updates false to your Chef client.rb configuration file.

Syntax

A log resource block adds messages to the log file based on events that occur during the chef-client run:

log 'message' do
  message 'A message add to the log.'
  level :info
end

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

log 'name' do
  level                      Symbol
  message                    String # defaults to 'name' if not specified
  notifies                   # see description
  provider                   Chef::Provider::ChefLog
  subscribes                 # see description
  action                     Symbol # defaults to :write if not specified
end

where

  • log is the resource
  • name is the name of the resource block
  • message is the log message to write
  • :action identifies the steps the chef-client will take to bring the node into the desired state
  • level, message, and provider are properties of this resource, with the Ruby type shown. See “Properties” section below for more information about all of the properties that may be used with this resource.

Actions

This resource has the following actions:

:nothing
Define this resource block to do nothing until notified by another resource to take action. When this resource is notified, this resource block is either run immediately or it is queued up to be run at the end of the chef-client run.
:write
Default. Write to log.

Properties

This resource has the following properties:

ignore_failure

Ruby Types: TrueClass, FalseClass

Continue running a recipe if a resource fails for any reason. Default value: false.

level

Ruby Type: Symbol

The level of logging that is to be displayed by the chef-client. The chef-client uses the mixlib-log (https://github.com/chef/mixlib-log) to handle logging behavior. Options (in order of priority): :debug, :info, :warn, :error, and :fatal. Default value: :info.

message

Ruby Type: String

The message to be added to a log file. Default value: the name of the resource block See “Syntax” section above for more information.

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 notifiy more than one resource; use a notifies statement for each resource to be notified.

A timer specifies the point during the chef-client run at which a notification is run. The following timers are available:

:delayed
Default. Specifies that a notification should be queued up, and then executed at the very end of the chef-client run.
:immediate, :immediately
Specifies that a notification should be run immediately, per resource notified.

The syntax for notifies is:

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

Ruby Type: Chef Class

Optional. Explicitly specifies a provider.

retries

Ruby Type: Integer

The number of times to catch exceptions and retry the resource. Default value: 0.

retry_delay

Ruby Type: Integer

The retry delay (in seconds). Default value: 2.

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.

A timer specifies the point during the chef-client run at which a notification is run. The following timers are available:

:delayed
Default. Specifies that a notification should be queued up, and then executed at the very end of the chef-client run.
:immediate, :immediately
Specifies that a notification should be run immediately, per resource notified.

The syntax for subscribes is:

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

Providers

Where a resource represents a piece of the system (and its desired state), a provider defines the steps that are needed to bring that piece of the system from its current state into the desired state.

The chef-client will determine the correct provider based on configuration data collected by Ohai at the start of the chef-client run. This configuration data is then mapped to a platform and an associated list of providers.

Generally, it’s best to let the chef-client choose the provider, and this is (by far) the most common approach. However, in some cases, specifying a provider may be desirable. There are two approaches:

  • Use a more specific short name—yum_package "foo" do instead of package "foo" do, script "foo" do instead of bash "foo" do, and so on—when available
  • Use the provider property within the resource block to specify the long name of the provider as a property of a resource. For example: provider Chef::Provider::Long::Name

This resource has the following providers:

Chef::Provider::Log::ChefLog, log
The default provider for all platforms.

Examples

The following examples demonstrate various approaches for using resources in recipes. If you want to see examples of how Chef uses resources in recipes, take a closer look at the cookbooks that Chef authors and maintains: https://github.com/chef-cookbooks.

Set default logging level

log 'a string to log'

Set debug logging level

log 'a debug string' do
  level :debug
end

Add a message to a log file

log 'message' do
  message 'This is the message that will be added to the log.'
  level :info
end

Use Chef::Log to create a log entry

The following example shows two log entries, one created using Chef::Log and the other using the log resource. Only the log entry created by the log resource is built into the resource collection.

...

client_bin = find_chef_client
Chef::Log.debug("Found chef-client in #{client_bin}")
node.default['chef_client']['bin'] = client_bin
create_directories

log 'Using winsw_service on this Chef version is deprecated; use windows_service' do
  level :warn
  only_if { Gem::Requirement.new('>= 11.5').satisfied_by?(Gem::Version.new(::Chef::VERSION)) }
end

...