ksh resource¶
Use the ksh resource to execute scripts using the Korn shell (ksh) interpreter. This resource may also use any of the actions and properties that are available to the execute resource. 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. New in Chef Client 12.6.
Note
The ksh script resource (which is based on the script resource) is different from the ruby_block resource because Ruby code that is run with this resource is created as a temporary file and executed like other script resources, rather than run inline.
Syntax¶
A ksh resource block executes scripts using ksh:
ksh 'hello world' do
code <<-EOH
echo "Hello world!"
echo "Current directory: " $cwd
EOH
end
where
code
specifies the command to run
The full syntax for all of the properties that are available to the ksh resource is:
ksh 'name' do
code String
creates String
cwd String
environment Hash
flags String
group String, Integer
notifies # see description
path Array
returns Integer, Array
subscribes # see description
timeout Integer, Float
user String, Integer
umask String, Integer
action Symbol # defaults to :run if not specified
end
where:
ksh
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.code
,creates
,cwd
,environment
,flags
,group
,path
,returns
,timeout
,user
, andumask
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¶
The ksh resource has the following actions:
:nothing
- Prevent a command from running. This action is used to specify that a command is run only when another resource notifies it.
:run
- Default. Run a script.
Properties¶
This resource has the following properties:
code
Ruby Type: String
A quoted (” “) string of code to be executed.
creates
Ruby Type: String
Prevent a command from creating a file when that file already exists.
cwd
Ruby Type: String
The current working directory.
environment
Ruby Type: Hash
A Hash of environment variables in the form of
({"ENV_VARIABLE" => "VALUE"})
. (These variables must exist for a command to be run successfully.)flags
Ruby Type: String
One or more command line flags that are passed to the interpreter when a command is invoked.
group
Ruby Type: String, Integer
The group name or group ID that must be changed before running a command.
ignore_failure
Ruby Type: true, false | Default Value:
false
Continue running a recipe if a resource fails for any reason.
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.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
path
Ruby Type: Array
An array of paths to use when searching for a command. These paths are not added to the command’s environment $PATH. The default value uses the system path.
Warning
For example:
ksh 'mycommand' do environment 'PATH' => "/my/path/to/bin:#{ENV['PATH']}" end
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).
returns
Ruby Type: Integer, Array | Default Value:
0
The return value for a command. This may be an array of accepted values. An exception is raised when the return value(s) do not match.
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 thenginx
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 examplenginx
) 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
timeout
Ruby Type: Integer, Float | Default Value:
3600
The amount of time (in seconds) a command is to wait before timing out.
user
Ruby Type: String, Integer
The user name or user ID that should be changed before running a command.
umask
Ruby Type: String, Integer
The file mode creation mask, or umask.
Guards¶
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:
- 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 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
- Prevent a resource from executing when the condition returns
true
. only_if
- Allow a resource to execute only if the condition returns
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
Examples¶
None.