log Resource
This page is generated from the Chef Infra Client source code.To suggest a change, edit the log.rb file and submit a pull request to the Chef Infra Client repository.
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 a Chef Infra 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 Chef Infra Client will take to bring the node into the desired state.level
andmessage
are the properties available to this resource.
Actions
The log resource has the following actions:
:nothing
- This resource block does not 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.
:write
- (default)
Properties
The log resource has the following properties:
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 | Default Value:
The resource block's name
The message to be added to a log file. Default value: the
name
of the resource block. See “Syntax” section above for more information.
Log Entries
Chef::Log
will print log entries to the default logger that is configured for the machine on which Chef Infra Client is running. (To create a log entry that is built into the resource collection, use the log resource instead of Chef::Log
.)
Supported log levels
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') |
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 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
...
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 (theconverge phase
).ignore_failure
Ruby Type: true, false, :quiet | Default Value:
false
Continue running a recipe if a resource fails for any reason.
:quiet
will not 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 is not 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 anotifies
statement for each resource to be notified.If the referenced resource does not exist, an error is raised. In contrast,
subscribes
will not fail if the source resource is not 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
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.
If the other resource does not exist, the subscription will not raise an
error. Contrast this with the stricter semantics of notifies
, which
will raise an error if the other resource does not 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 is not applied. String guards in a powershell_script run Windows PowerShell commands and may returntrue
in addition to0
. - A block is executed as Ruby code that must return either
true
orfalse
. If the block returnstrue
, the guard property is applied. If the block returnsfalse
, the guard property is not 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 is being executed, and then if the desired state is present, for Chef Infra Client to do nothing.
PropertiesThe following properties can be used to define a guard that is 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 log resource in recipes:
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