chef_gem Resource
This page is generated from the Chef Infra Client source code.To suggest a change, edit the chef_gem.rb file and submit a pull request to the Chef Infra Client repository.
Use the chef_gem resource to install a gem only for the instance of Ruby that is dedicated to the Chef Infra Client. When a gem is installed from a local file, it must be added to the node using the remote_file or cookbook_file resources.
The chef_gem resource works with all of the same properties and options as the gem_package resource, but does not
accept the gem_binary
property because it always uses the CurrentGemEnvironment
under which the chef-client
is
running. In addition to performing actions similar to the gem_package resource, the chef_gem resource does the
following:
- Runs its actions immediately, before convergence, allowing a gem to be used in a recipe immediately after it is installed.
- Runs
Gem.clear_paths
after the action, ensuring that gem is aware of changes so that it can be required immediately after it is installed.
Warning
The chef_gem and gem_package resources are both used to install Ruby gems. For any machine on which Chef Infra Client is installed, there are two instances of Ruby. One is the standard, system-wide instance of Ruby and the other is a dedicated instance that is available only to Chef Infra Client. Use the chef_gem resource to install gems into the instance of Ruby that is dedicated to Chef Infra Client. Use the gem_package resource to install all other gems (i.e. install gems system-wide).
Syntax
The full syntax for all of the properties that are available to the chef_gem resource is:
chef_gem 'name' do
clear_sources true, false
gem_binary String
include_default_source true, false
options String, Hash, Array
package_name String
source String, Array
timeout String, Integer
version String
action Symbol # defaults to :install if not specified
end
where:
chef_gem
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.clear_sources
,gem_binary
,include_default_source
,options
,package_name
,source
,timeout
, andversion
are the properties available to this resource.
Actions
The chef_gem resource has the following actions:
:install
- Install a gem. If a version is specified, install the specified version of the gem. (default)
: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.
:purge
- Purge a gem. This action typically removes the configuration files as well as the gem.
:reconfig
- Reconfigure a gem. This action requires a response file.
:remove
- Remove a gem.
:upgrade
- Install a gem and ensure that a gem is the latest version.
Properties
The chef_gem resource has the following properties:
clear_sources
- Ruby Type: true, false | Default Value:
false unless `clear_gem_sources` set to true in the `client.rb` config.
Set to
true
to download a gem from the path specified by thesource
property (and not from RubyGems).
gem_binary
- Ruby Type: String | Default Value:
The `gem` binary included with Chef Infra Client.
The path of a gem binary to use for the installation. By default, the same version of Ruby that is used by Chef Infra Client will be used.
include_default_source
- Ruby Type: true, false
Set to
false
to not includeChef::Config[:rubygems_url]
in the sources.New in Chef Client 13.0
options
- Ruby Type: String, Hash, Array
Options for the gem install, either a Hash or a String. When a hash is given, the options are passed to
Gem::DependencyInstaller.new
, and the gem will be installed via the gems API. When a String is given, the gem will be installed by shelling out to the gem command. Using a Hash of options with an explicit gem_binary will result in undefined behavior.
package_name
- Ruby Type: String
An optional property to set the package name if it differs from the resource block’s name.
source
- Ruby Type: String, Array
Optional. The URL, or list of URLs, at which the gem package is located. This list is added to the source configured in
Chef::Config[:rubygems_url]
(see also include_default_source) to construct the complete list of rubygems sources. Users in an ‘airgapped’ environment should set Chef::Config[:rubygems_url] to their local RubyGems mirror.
timeout
- Ruby Type: String, Integer
The amount of time (in seconds) to wait before timing out.
version
- Ruby Type: String
The version of a package to be installed or upgraded.
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 chef_gem resource in recipes:
Compile time vs. converge time installation of gems
To install a gem while Chef Infra Client is configuring the node (the converge phase), set the compile_time
property to false
:
chef_gem 'loofah' do
compile_time false
action :install
end
To install a gem while the resource collection is being built (the compile phase), set the compile_time
property to true
:
chef_gem 'loofah' do
compile_time true
action :install
end
Install MySQL gem into Chef Infra Client*
apt_update
build_essential 'install compilation tools' do
compile_time true
end
chef_gem 'mysql'