script resource¶
Use the script resource to execute scripts using a specified interpreter, such as Bash, csh, Perl, Python, or Ruby. 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.
Note
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.
This resource is the base resource for several other resources used for scripting on specific platforms. For more information about specific resources for specific platforms, see the following topics:
Changed in 12.19 to support windows alternate user identity in execute resources
Syntax¶
A script resource block typically executes scripts using a specified interpreter, such as Bash, csh, Perl, Python, or Ruby:
script 'extract_module' do
interpreter "bash"
cwd ::File.dirname(src_filepath)
code <<-EOH
mkdir -p #{extract_path}
tar xzf #{src_filename} -C #{extract_path}
mv #{extract_path}/*/* #{extract_path}/
EOH
not_if { ::File.exist?(extract_path) }
end
where
interpreter
specifies the command shell to usecwd
specifies the directory from which the command is runcode
specifies the command to run
It is more common to use the script-based resource that is specific to the command shell. Chef has shell-specific resources for Bash, csh, Perl, Python, and Ruby.
The same command as above, but run using the bash resource:
bash 'extract_module' do
cwd ::File.dirname(src_filepath)
code <<-EOH
mkdir -p #{extract_path}
tar xzf #{src_filename} -C #{extract_path}
mv #{extract_path}/*/* #{extract_path}/
EOH
not_if { ::File.exist?(extract_path) }
end
The full syntax for all of the properties that are available to the script resource is:
script 'name' do
code String
creates String
cwd String
environment Hash
flags String
group String, Integer
interpreter String
notifies # see description
path Array
returns Integer, Array
subscribes # see description
timeout Integer, Float
user String
password String
domain String
umask String, Integer
action Symbol # defaults to :run if not specified
end
where
script
is the resourcename
is the name of the resource blockcwd
is the location from which the command is runaction
identifies the steps the chef-client will take to bring the node into the desired statecode
,creates
,cwd
,environment
,flags
,group
,interpreter
,path
,returns
,timeout
,user
,password
,domain
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 script 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 attributes:
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.
interpreter
Ruby Type: String
The script interpreter to use during code execution.
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:
script '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
The user name of the user identity with which to launch the new process. Default value: nil. The user name may optionally be specified with a domain, i.e. domainuser or user@my.dns.domain.com via Universal Principal Name (UPN)format. It can also be specified without a domain simply as user if the domain is instead specified using the domain attribute. On Windows only, if this property is specified, the password property must be specified.
password
Ruby Type: String
Windows only: The password of the user specified by the user property. Default value: nil. This property is mandatory if user is specified on Windows and may only be specified if user is specified. The sensitive property for this resource will automatically be set to true if password is specified.
domain
Ruby Type: String
Windows only: The domain of the user user specified by the user property. Default value: nil. If not specified, the user name and password specified by the user and password properties will be used to resolve that user against the domain in which the system running Chef client is joined, or if that system is not joined to a domain it will resolve the user as a local account on that system. An alternative way to specify the domain is to leave this property unspecified and specify the domain as part of the user property.
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
Guard Interpreter¶
Any resource that passes a string command may also specify the interpreter that will be used to evaluate that string command. This is done by using the guard_interpreter
property to specify a script-based resource.
Attributes
The guard_interpreter
property may be set to any of the following values:
:bash
- Evaluates a string command using the bash resource.
:batch
- Evaluates a string command using the batch resource. Default value (within a batch resource block):
:batch
. :csh
- Evaluates a string command using the csh resource.
:default
- Default. Executes the default interpreter as identified by the chef-client.
:perl
- Evaluates a string command using the perl resource.
:powershell_script
- Evaluates a string command using the powershell_script resource. Default value (within a batch resource block):
:powershell_script
. :python
- Evaluates a string command using the python resource.
:ruby
- Evaluates a string command using the ruby resource.
Inheritance
The guard_interpreter
property is set to :default
by default for the bash, csh, perl, python, and ruby resources. When the guard_interpreter
property is set to :default
, not_if
or only_if
guard statements do not inherit properties that are defined by the script-based resource.
Warning
The batch and powershell_script resources inherit properties by default. The guard_interpreter
property is set to :batch
or :powershell_script
automatically when using a not_if
or only_if
guard statement within a batch or powershell_script resource, respectively.
For example, the not_if
guard statement in the following resource example does not inherit the environment
property:
bash 'javatooling' do
environment 'JAVA_HOME' => '/usr/lib/java/jdk1.7/home'
code 'java-based-daemon-ctl.sh -start'
not_if 'java-based-daemon-ctl.sh -test-started'
end
and requires adding the environment
property to the not_if
guard statement so that it may use the JAVA_HOME
path as part of its evaluation:
bash 'javatooling' do
environment 'JAVA_HOME' => '/usr/lib/java/jdk1.7/home'
code 'java-based-daemon-ctl.sh -start'
not_if 'java-based-daemon-ctl.sh -test-started', :environment => 'JAVA_HOME' => '/usr/lib/java/jdk1.7/home'
end
To inherit properties, add the guard_interpreter
property to the resource block and set it to the appropriate value:
:bash
for bash:csh
for csh:perl
for perl:python
for python:ruby
for ruby
For example, using the same example as from above, but this time adding the guard_interpreter
property and setting it to :bash
:
bash 'javatooling' do
guard_interpreter :bash
environment 'JAVA_HOME' => '/usr/lib/java/jdk1.7/home'
code 'java-based-daemon-ctl.sh -start'
not_if 'java-based-daemon-ctl.sh -test-started'
end
The not_if
statement now inherits the environment
property and will use the JAVA_HOME
path as part of its evaluation.
Example
For example, the following code block will ensure the command is evaluated using the default interpreter as identified by the chef-client:
resource 'name' do
guard_interpreter :default
# code
end
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.
Use a named provider to run a script
bash 'install_something' do
user 'root'
cwd '/tmp'
code <<-EOH
wget http://www.example.com/tarball.tar.gz
tar -zxf tarball.tar.gz
cd tarball
./configure
make
make install
EOH
end
Run a script
script 'install_something' do
interpreter 'bash'
user 'root'
cwd '/tmp'
code <<-EOH
wget http://www.example.com/tarball.tar.gz
tar -zxf tarball.tar.gz
cd tarball
./configure
make
make install
EOH
end
or something like:
bash 'openvpn-server-key' do
environment('KEY_CN' => 'server')
code <<-EOF
openssl req -batch -days #{node['openvpn']['key']['expire']} \
-nodes -new -newkey rsa:#{key_size} -keyout #{key_dir}/server.key \
-out #{key_dir}/server.csr -extensions server \
-config #{key_dir}/openssl.cnf
EOF
not_if { File.exist?('#{key_dir}/server.crt') }
end
where code
contains the OpenSSL command to be run. The not_if
property tells the chef-client not to run the command if the file already exists.
Install a file from a remote location using bash
The following is an example of how to install the foo123
module for Nginx. This module adds shell-style functionality to an Nginx configuration file and does the following:
- Declares three variables
- Gets the Nginx file from a remote location
- Installs the file using Bash to the path specified by the
src_filepath
variable
# the following code sample is similar to the ``upload_progress_module``
# recipe in the ``nginx`` cookbook:
# https://github.com/chef-cookbooks/nginx
src_filename = "foo123-nginx-module-v#{
node['nginx']['foo123']['version']
}.tar.gz"
src_filepath = "#{Chef::Config['file_cache_path']}/#{src_filename}"
extract_path = "#{
Chef::Config['file_cache_path']
}/nginx_foo123_module/#{
node['nginx']['foo123']['checksum']
}"
remote_file 'src_filepath' do
source node['nginx']['foo123']['url']
checksum node['nginx']['foo123']['checksum']
owner 'root'
group 'root'
mode '0755'
end
bash 'extract_module' do
cwd ::File.dirname(src_filepath)
code <<-EOH
mkdir -p #{extract_path}
tar xzf #{src_filename} -C #{extract_path}
mv #{extract_path}/*/* #{extract_path}/
EOH
not_if { ::File.exist?(extract_path) }
end
Install an application from git using bash
The following example shows how Bash can be used to install a plug-in for rbenv named ruby-build
, which is located in git version source control. First, the application is synchronized, and then Bash changes its working directory to the location in which ruby-build
is located, and then runs a command.
git "#{Chef::Config[:file_cache_path]}/ruby-build" do
repository 'git://github.com/sstephenson/ruby-build.git'
reference 'master'
action :sync
end
bash 'install_ruby_build' do
cwd '#{Chef::Config[:file_cache_path]}/ruby-build'
user 'rbenv'
group 'rbenv'
code <<-EOH
./install.sh
EOH
environment 'PREFIX' => '/usr/local'
end
To read more about ruby-build
, see here: https://github.com/sstephenson/ruby-build.
Store certain settings
The following recipe shows how an attributes file can be used to store certain settings. An attributes file is located in the attributes/
directory in the same cookbook as the recipe which calls the attributes file. In this example, the attributes file specifies certain settings for Python that are then used across all nodes against which this recipe will run.
Python packages have versions, installation directories, URLs, and checksum files. An attributes file that exists to support this type of recipe would include settings like the following:
default['python']['version'] = '2.7.1'
if python['install_method'] == 'package'
default['python']['prefix_dir'] = '/usr'
else
default['python']['prefix_dir'] = '/usr/local'
end
default['python']['url'] = 'http://www.python.org/ftp/python'
default['python']['checksum'] = '80e387...85fd61'
and then the methods in the recipe may refer to these values. A recipe that is used to install Python will need to do the following:
- Identify each package to be installed (implied in this example, not shown)
- Define variables for the package
version
and theinstall_path
- Get the package from a remote location, but only if the package does not already exist on the target system
- Use the bash resource to install the package on the node, but only when the package is not already installed
# the following code sample comes from the ``oc-nginx`` cookbook on |github|: https://github.com/cookbooks/oc-nginx
version = node['python']['version']
install_path = "#{node['python']['prefix_dir']}/lib/python#{version.split(/(^\d+\.\d+)/)[1]}"
remote_file "#{Chef::Config[:file_cache_path]}/Python-#{version}.tar.bz2" do
source "#{node['python']['url']}/#{version}/Python-#{version}.tar.bz2"
checksum node['python']['checksum']
mode '0755'
not_if { ::File.exist?(install_path) }
end
bash 'build-and-install-python' do
cwd Chef::Config[:file_cache_path]
code <<-EOF
tar -jxvf Python-#{version}.tar.bz2
(cd Python-#{version} && ./configure #{configure_options})
(cd Python-#{version} && make && make install)
EOF
not_if { ::File.exist?(install_path) }
end
Run a command as an alternate user
Note: When Chef is running as a service, this feature requires that the user that Chef runs as has ‘SeAssignPrimaryTokenPrivilege’ (aka ‘SE_ASSIGNPRIMARYTOKEN_NAME’) user right. By default only LocalSystem and NetworkService have this right when running as a service. This is necessary even if the user is an Administrator.
This right can be added and checked in a recipe using this example:
# Add 'SeAssignPrimaryTokenPrivilege' for the user
Chef::ReservedNames::Win32::Security.add_account_right('<user>', 'SeAssignPrimaryTokenPrivilege')
# Check if the user has 'SeAssignPrimaryTokenPrivilege' rights
Chef::ReservedNames::Win32::Security.get_account_right('<user>').include?('SeAssignPrimaryTokenPrivilege')
The following example shows how to run mkdir test_dir
from a chef-client run as an alternate user.
# Passing only username and password
script 'mkdir test_dir' do
interpreter "bash"
code "mkdir test_dir"
cwd Chef::Config[:file_cache_path]
user "username"
password "password"
end
# Passing username and domain
script 'mkdir test_dir' do
interpreter "bash"
code "mkdir test_dir"
cwd Chef::Config[:file_cache_path]
domain "domain-name"
user "username"
password "password"
end
# Passing username = 'domain-name\\username'. No domain is passed
script 'mkdir test_dir' do
interpreter "bash"
code "mkdir test_dir"
cwd Chef::Config[:file_cache_path]
user "domain-name\\username"
password "password"
end
# Passing username = 'username@domain-name'. No domain is passed
script 'mkdir test_dir' do
interpreter "bash"
code "mkdir test_dir"
cwd Chef::Config[:file_cache_path]
user "username@domain-name"
password "password"
end