Page Comparison

Requirement

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Overview

DMTF’s Redfish is a standard API designed to deliver simple and secure management for converged, hybrid IT and the Software Defined Data Center (SDDC). Both human readable and machine capable, Redfish leverages common Internet and web services standards to expose information directly to the modern tool chain. Delivering both in‐band and out‐of‐band manageability, Redfish continues to expand to address customer use cases and technology for a holistic data center management experience.

Why Redfish?

Until Redfish, interoperable management standards were lacking for modern data center environments. As organizations shift to scale‐ out solutions, legacy standards are insufficient to successfully manage numerous simple and multi‐node servers or hybrid infrastructures. Legacy solutions has problems related to security and HW dependencies, lacking the agnostic nature thats needed for the modern datacenter.

An open industry standard specification and schema, Redfish specifies a RESTful interface and utilizes defined JSON payloads ‐ usable by existing client applications and browser‐based GUI.  

Why REST, HTTP and JSON?

Combining language support with the ubiquity of REST, HTTP and JSON, Redfish enables IT management tasks to be performed using the same skill set and tool chain as other IT and dev/ops tasks.RESTful protocols are rapidly replacing SOAP as the cloud ecosystem is adopting REST, and the web API community has followed suit. RESTful protocols are much quicker to learn than SOAP, and they have the simplicity of being a data pattern (as REST is not strictly a protocol) mapped to HTTP operations directly.

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Plugin configuration

The following configuration options should be supported by redfish collectd plugin:  

Here is an example of the plugin configuration section of collectd.conf file for the python based plugin module:

<Plugin python>

Import "redfish_sensors_plugin"

<Module "redfish_sensors_plugin">

Username "<username>"

Password "<password>"

Interval <poll-interval-seconds>

sensor ["fan:power:thermal"]

Address  "<ipaddress>"

Version  "[v1]"

Verbose false

Debug false

</Module>

</Plugin>

Note :  Plan is to move from python based plugin to C based plugin

Implementation details

To support the redfish based sensor monitoring, the standard redfish interfaces are used as mentioned in the DMTF. Idea is to use as much possible the standard REST API URLs to reach the sensor resources. In order to implement and utilize the redfish interfaces one must understand the concept of resoure maps in DMTF redfish architecture. 

The resource traversing for each elements can happen via well defined resource map. As described in the below diagram, These resource maps can be used directly to depict the REST URL to use GET or POST requests to certain resources. For the purpose of this plugin, the main focus is on the resources below /"redfish/v1/Chassis/<id>".   

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Resource Map in Redfish (courtsey : DMTF)

 Following :

<Plugin redfish>
  <Query "fans">
    Endpoint "/redfish/v1/Chassis/Chassis-1/Thermal"
    <Resource "Fans">
      <Property "ReadingRPM">
        PluginInstance "chassis-1"
        Type "rpm"
      </Property>
    </Resource>
  </Query>
  <Query "temperatures">
    Endpoint "/redfish/v1/Chassis/Chassis-1/Thermal"
    <Resource "Temperatures">
      <Property "ReadingCelsius">
        PluginInstance "chassis-1"
        Type "degrees"
      </Property>
    </Resource>
  </Query>
  <Query "voltages">
    Endpoint "/redfish/v1/Chassis/Chassis-1/Power"
    <Resource "Voltages">
      <Property "ReadingVolts">
        PluginInstance "chassis-1"
        Type "volts"
      </Property>
    </Resource>
  </Query>
  <Service "local">
    Host "127.0.0.1:5000"
    User "user"
    Passwd "passwd"
    Queries "fans" "voltages" "temperatures"
  </Service>
</Plugin>

Implementation details

To support the redfish based sensor monitoring, the standard redfish interfaces are used as mentioned in the DMTF. Idea is to use as much possible the standard REST API URLs to reach the sensor resources. In order to implement and utilize the redfish interfaces one must understand the concept of resource maps in DMTF redfish architecture. 

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Following redfish REST query outputs the current sensor status of Fan (for "Fan_SYS4_2" with member id 9) and its corresponding metadata. "ReadingRPM" parameters is the main value of concern here which shows the current Fanspeed.

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