log resource¶

[edit on GitHub]

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 # default value: info
  message      String # default value: 'name' unless specified
  action       Symbol # defaults to :write if not specified
end

where:

log is the resource.
name is the name given to the resource block.
action identifies which steps the chef-client will take to bring the node into the desired state.
level and message are the properties available to this resource.

Actions¶

The log 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¶

The log resource has the following properties:

ignore_failure

Ruby Type: true, false | Default Value: false

Continue running a recipe if a resource fails for any reason.

level

Ruby Type: Symbol | Default Value: :info

The logging level for displaying this message.. Options (in order of priority): :debug, :info, :warn, :error, and :fatal.

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 notify 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 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

retries

Ruby Type: Integer | Default Value: 0

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

retry_delay

Ruby Type: Integer | Default Value: 2

The retry delay (in seconds).

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 does not 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 does not 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.

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

Note

The parentheses are optional, e.g. Chef::Log.info 'string' may be used instead of Chef::Log.info('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
  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