http_request resource¶

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Use the http_request resource to send an HTTP request (GET, PUT, POST, DELETE, HEAD, or OPTIONS) with an arbitrary message. This resource is often useful when custom callbacks are necessary.

Syntax¶

A http_request resource block sends HTTP requests with an arbitrary message. For example, send a DELETE request to 'http://www.chef.io/some_page?message=please_delete_me'.

http_request 'please_delete_me' do
  url 'http://www.chef.io/some_page'
  action :delete
end

The full syntax for all of the properties that are available to the http_request resource is:

http_request 'name' do
  headers                    Hash
  message                    Object # defaults to 'name' if not specified
  notifies                   # see description
  subscribes                 # see description
  url                        String
  action                     Symbol # defaults to :get if not specified
end

where:

http_request 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.
headers, message, and url 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 http_request resource has the following actions:

:delete

Send a DELETE request.

:get

Default. Send a GET request.

Changed in Chef Client 12.0 to deprecate the hard-coded query string from earlier versions. Cookbooks that rely on this string need to be updated to manually add it to the URL as it is passed to the resource.

:head

Send a HEAD request.

:nothing

Define this resource block to do nothing until notified by another resource to take action. When this resource is notified, this resource block is either run immediately or it is queued up to be run at the end of the Chef Client run.

:options

Send an OPTIONS request.

:post

Send a POST request.

:put

Send a PUT request.

Properties¶

The http_request resource has the following properties:

headers

Ruby Type: Hash

A Hash of custom headers.

ignore_failure

Ruby Type: true, false | Default Value: false

Continue running a recipe if a resource fails for any reason.

message

Ruby Type: Object

The message that is sent by the HTTP request. Default value: the name of the resource block. See “Syntax” section above for more information.

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 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: 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

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).

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.

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

url

Ruby Type: String

The URL to which an HTTP request is sent.

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.

Send a GET request

http_request 'some_message' do
  url 'http://example.com/check_in'
end

The message is sent as http://example.com/check_in?message=some_message.

Send a POST request

To send a POST request as JSON data, convert the message to JSON and include the correct content-type header. For example:

http_request 'posting data' do
  action :post
  url 'http://example.com/check_in'
  message ({:some => 'data'}.to_json)
  headers({'AUTHORIZATION' => "Basic #{
    Base64.encode64('username:password')}",
    'Content-Type' => 'application/data'
  })
end

Transfer a file only when the remote source changes

remote_file '/tmp/couch.png' do
  source 'http://couchdb.apache.org/img/sketch.png'
  action :nothing
end

http_request 'HEAD http://couchdb.apache.org/img/sketch.png' do
  message ''
  url 'http://couchdb.apache.org/img/sketch.png'
  action :head
  if ::File.exist?('/tmp/couch.png')
    headers 'If-Modified-Since' => File.mtime('/tmp/couch.png').httpdate
  end
  notifies :create, 'remote_file[/tmp/couch.png]', :immediately
end