train-rest - Train transport

Provides a transport to communicate easily with RESTful APIs.

Requirements

• Gem rest-client in Version 2.1

Installation

You will have to build this gem yourself to install it as it is not yet on Rubygems.Org. For this there is a rake task which makes this a one-liner:

rake install:local

Transport parameters

Option	Explanation	Default
endpoint	Endpoint of the REST API	required
verify_ssl	Check certificate and chain	true
auth_type	Authentication type	anonymous
debug_rest	Enable debugging of HTTP traffic	false
logger	Alternative logging class

Authenticators

Anonymous

Identifier: auth_type: :anonymous

No actions for authentication, logging in/out or session handing are made. This assumes a public API.

Basic Authentication

Identifier: auth_type: :basic

Option	Explanation	Default
username	Username for basic authentication	required
password	Password for basic authentication	required

If you supply a username and a password, authentication will automatically switch to basic.

Redfish

Identifier: auth_type: :redfish

Option	Explanation	Default
username	Username for redfish authentication	required
password	Password for redfish authentication	required

For access to integrated management controllers on standardized server hardware. The Redfish standard is defined in http://www.dmtf.org/standards/redfish and this handler does initial login, reuses the received session and logs out when closing the transport cleanly.

Known vendors which implement RedFish based management for their systems include HPE, Dell, IBM, SuperMicro, Lenovo, Huawei and others.

Debugging and use in Chef

You can activate debugging by setting the debug_rest flag to `true'. Please note, that this will also log any confidential parts of HTTP traffic as well.

For better integration into Chef custom resources, all REST debug output will be printed on info level. This allows debugging Chef resources without crawling through all other debug output:

train  = Train.create('rest', {
            endpoint:   'https://api.example.com/v1/',
            debug_rest: true,
            logger:     Chef::Log
         })

Request Methods

This transport does not implement the run_command method, as there is no line-based protocol to execute commands against. Instead, it implements its own custom methods which suit REST interfaces. Trying to call this method will throw an Exception.

Generic Request

The request methods allows to send free-form requests against any defined or custom methods.

request(path, method = :get, request_parameters: {}, data: nil, headers: {}, json_processing: true)

• path: The path to request, which will be appended to the endpoint
• method: The HTTP method in Ruby Symbol syntax
• request_parameters: A hash of parameters to the rest-client request method for additional settings
• data: Data for actions like :post or :put. Not all methods accept a data body.
• headers: Additional headers for the request
• json_processing: If the response is a JSON and you want to receive a processed Hash/Array instead of text

For request_parameters and headers, there is data mixed in to add authenticator responses, JSON processing etc. Please check the implementation in connection.rb for details.

Convenience Methods

Simplified wrappers are generated for the most common request types:

• delete(path, request_parameters: {}, headers: {}, json_processing: true)
• head(path, request_parameters: {}, headers: {}, json_processing: true)
• get(path, request_parameters: {}, headers: {}, json_processing: true)
• post(path, request_parameters: {}, data: nil, headers: {}, json_processing: true)
• put(path, request_parameters: {}, data: nil, headers: {}, json_processing: true)
• patch(path, request_parameters: {}, data: nil, headers: {}, json_processing: true)

Example use

require 'train-rest'

train  = Train.create('rest', {
            endpoint: 'https://api.example.com/v1/',

            logger:   Logger.new($stdout, level: :info)
         })
conn   = train.connection

# Get some hypothetical data
data   = conn.get('device/1/settings')

# Modify + Patch
data['disabled'] = false
conn.patch('device/1/settings', data)

conn.close

Example for basic authentication:

require 'train-rest'

# This will immediately do a login and add headers
train  = Train.create('rest', {
            endpoint: 'https://api.example.com/v1/',

            auth_type: :basic,
            username: 'admin',
            password: '*********'
         })
conn   = train.connection

# ... do work, each request will resend Basic authentication headers ...

conn.close

Example for logging into a RedFish based system. Please note that the RedFish authentication handler will append redfish/v1 to the endpoint automatically, if it is not present.

Due to this, you can use RedFish systems either with a base URL like in the example below or with a full one. Your own code needs to match the style you choose.

require 'train-rest'

# This will immediately do a login and add headers
train  = Train.create('rest', {
            endpoint: 'https://10.20.30.40',
            verify_ssl: false,

            auth_type: :redfish,
            username: 'iloadmin',
            password: '*********'
         })
conn   = train.connection

# ... do work ...

# Handles logout as well
conn.close

Use with Redfish, Your Custom Resources and Chef Target Mode

1. Set up a credentials file under ~/.chef/credentials or /etc/chef/credentials:

   ['10.0.0.1']
   endpoint = 'https://10.0.0.1/redfish/v1/'
   username = 'user'
   password = 'pass'
   verify_ssl = false
   auth_type = 'redfish'

1. Configure Chef to use the REST transport in client.rb:

   target_mode.protocol = "rest"

1. Write your custom resources for REST APIs
2. Mark them up using the REST methods for target mode:

   provides :rest_resource, target_mode: true, platform: 'rest'

1. Run against the defiend targets via Chef Target Mode:

   chef-client --local-mode --target 10.0.0.1 --runlist 'recipe[my-cookbook::setup]'

Use with Prerecorded API responses

For testing during and after development, not all APIs can be used to verify your solution against. The VCR gem offers the possibility to hook into web requests and intercept them to play back canned responses.

Please read the documentation of the VCR gem on how to record your API and the concepts like "cassettes", "libraries" and matchers.

The following options are available in train-rest for this:

Option	Explanation	Default
vcr_cassette	Name of the response file	nil
vcr_library	Directory to search responses in	vcr
vcr_match_on	Elements to match request by	method uri
vcr_record	Recording mode	none
vcr_hook_into	Base library for intercepting	webmock

VCR will only be required as a Gem and activated, if you supply a cassette name.

You can use all these settings in your Chef Target Mode credentials file as well.