train-rest - Train transport

Provides a transport to communicate easily with RESTful APIs.

Requirements

• Gem rest-client in Version 2.1
• Gem awssig-v4

Installation

The gem can be installed from RubyGems or built locally with an included Rake task:

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.

Authtype Apikey

This will inject a HTTP header Authorization: Apikey xxxx with the passed API key into requests.

Identifier: auth_type: :authtype_apikey

Option	Explanation	Default
apikey	API Key for authentication	required

AWS Signature v4

Identifier: auth_type: :awsv4

Option	Explanation	Default
credentials	Type of credentials to use	access_keys
access_key	ID of the access key	ENV: ACCESS_KEY_ID
secret_access_key	Secret part of the access key	ENV: SECRET_ACCESS_KEY

Only access_keys are supported as a credential currently. Support for other types, like EC2 roles, is planned.

Access key and secret access key are pulled from the mentioned environment variables, if they are not provided.

Basic (RFC 2617)

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.

Bearer (RFC 7650)

This will inject a HTTP header Authorization: Bearer xxxx with the passed token into requests.

Identifier: auth_type: :bearer

Option	Explanation	Default
token	Token to pass	required

Header-based

This will inject an additional HTTP header with the passed value. If no name for the header is passed, it will default to X-API-Key.

Identifier: auth_type: :header

Option	Explanation	Default
apikey	API Key for authentication	required
header	Name of the HTTP header to include	X-API-Key

HMAC Signature

Identifier: auth_type: :hmac_signature

Option	Explanation	Default
hmac_secret	Shared secret to use for signing on	required
header	Name of header to add	X-Signature
digest	OpenSSL Digest type supported by Ruby	SHA256

This will use the request body (payload) and sign it using HMAC. For a full list of supported digest, look at the Ruby documentation

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 Infra

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 Infra custom resources, all REST debug output will be printed on info level. This allows debugging Chef Infra 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 method allows sending 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 Infra 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'

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

   target_mode.protocol = "rest"

3. Write your custom resources for REST APIs

4. Mark them up using the REST methods for target mode:

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

5. Run against the defined targets via Chef Infra 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 playback 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 Infra Target Mode credentials file as well.