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.)

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:

: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 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:

: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 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

Chef::Log Entries

Chef::Log extends Mixlib::Log and will print log entries to the default logger that is configured for the machine on which the chef-client is running. (To create a log entry that is built into the resource collection, use the log resource instead of Chef::Log.)

The following log levels are supported:

Log Level	Syntax
Debug	Chef::Log.debug('string')
Error	Chef::Log.error('string')
Fatal	Chef::Log.fatal('string')
Info	Chef::Log.info('string')
Warn	Chef::Log.warn('string')

The following example shows a series of fatal Chef::Log entries:

unless node['splunk']['upgrade_enabled']
  Chef::Log.fatal('The chef-splunk::upgrade recipe was added to the node,')
  Chef::Log.fatal('but the attribute `node["splunk"]["upgrade_enabled"]` was not set.')
  Chef::Log.fatal('I am bailing here so this node does not upgrade.')
  raise
end

service 'splunk_stop' do
  service_name 'splunk'
  supports :status => true
  provider Chef::Provider::Service::Init
  action :stop
end

if node['splunk']['is_server']
  splunk_package = 'splunk'
  url_type = 'server'
else
  splunk_package = 'splunkforwarder'
  url_type = 'forwarder'
end

splunk_installer splunk_package do
  url node['splunk']['upgrade']["#{url_type}_url"]
end

if node['splunk']['accept_license']
  execute 'splunk-unattended-upgrade' do
    command "#{splunk_cmd} start --accept-license --answer-yes"
  end
else
  Chef::Log.fatal('You did not accept the license (set node["splunk"]["accept_license"] to true)')
  Chef::Log.fatal('Splunk is stopped and cannot be restarted until the license is accepted!')
  raise
end

The full recipe is the upgrade.rb recipe of the chef-splunk cookbook that is maintained by Chef.

The following example shows using multiple Chef::Log entry types:

...

begin
  aws = Chef::DataBagItem.load(:aws, :main)
  Chef::Log.info("Loaded AWS information from DataBagItem aws[#{aws['id']}]")
rescue
  Chef::Log.fatal("Could not find the 'main' item in the 'aws' data bag")
  raise
end

...

The full recipe is in the ebs_volume.rb recipe of the database cookbook that is maintained by Chef.

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