Use the erl_call resource to connect to a node located within a distributed Erlang system. Commands that are executed with this resource are (by their nature) not idempotent, as they are typically unique to the environment in which they are run. Use not_if
and only_if
to guard this resource for idempotence.
Note
The erl_call
command needs to be on the path for this resource to work properly.
A erl_call resource block connects to a node located within a distributed Erlang system:
erl_call 'list names' do code 'net_adm:names().' distributed true node_name '[email protected]' end
The full syntax for all of the properties that are available to the erl_call resource is:
erl_call 'name' do code String cookie String distributed TrueClass, FalseClass name_type String node_name String notifies # see description provider Chef::Provider::ErlCall subscribes # see description action Symbol # defaults to :run if not specified end
where
erl_call
is the resourcename
is the name of the resource block:action
identifies the steps the chef-client will take to bring the node into the desired statecode
, cookie
, distributed
, name_type
, node_name
, 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.This resource has the following actions:
:nothing
:run
This resource has the following properties:
code
Ruby Type: String
The code to be executed on a node located within a distributed Erlang system. Default value: q()
.
cookie
Ruby Type: String
The magic cookie for the node to which a connection is made.
distributed
Ruby Types: TrueClass, FalseClass
The node is a distributed Erlang node. Default value: false
.
ignore_failure
Ruby Types: TrueClass, FalseClass
Continue running a recipe if a resource fails for any reason. Default value: false
.
name_type
Ruby Type: String
The node_name
property as a short node name (sname
) or a long node name (name
). A node with a long node name cannot communicate with a node with a short node name. Default value: sname
.
node_name
Ruby Type: String
The hostname to which the node is to connect. Default value: [email protected]
.
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
:delayed
:immediate
, :immediately
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
:delayed
:immediate
, :immediately
The syntax for subscribes
is:
subscribes :action, 'resource[name]', :timer
A guard property can be used to evaluate the state of a node during the execution phase of the chef-client run. Based on the results of this evaluation, a guard property is then used to tell the chef-client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:
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 return true
in addition to 0
.true
or false
. If the block returns true
, the guard property is applied. If the block returns false
, 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 the chef-client to do nothing.
Attributes
The following properties can be used to define a guard that is evaluated during the execution phase of the chef-client run:
not_if
true
.only_if
true
.Arguments
The following arguments can be used with the not_if
or only_if
guard properties:
:user
Specify the user that a command will run as. For example:
not_if 'grep adam /etc/passwd', :user => 'adam'
:group
Specify the group that a command will run as. For example:
not_if 'grep adam /etc/passwd', :group => 'adam'
:environment
Specify a Hash of environment variables to be set. For example:
not_if 'grep adam /etc/passwd', :environment => { 'HOME' => '/home/adam' }
:cwd
Set the current working directory before running a command. For example:
not_if 'grep adam passwd', :cwd => '/etc'
:timeout
Set a timeout for a command. For example:
not_if 'sleep 10000', :timeout => 10
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.
Run a command
erl_call 'list names' do code 'net_adm:names().' distributed true node_name '[email protected]' end
© Chef Software, Inc.
Licensed under the Creative Commons Attribution 3.0 Unported License.
The Chef™ Mark and Chef Logo are either registered trademarks/service marks or trademarks/servicemarks of Chef, in the United States and other countries and are used with Chef Inc's permission.
We are not affiliated with, endorsed or sponsored by Chef Inc.
https://docs-archive.chef.io/release/12-13/resource_erlang_call.html