Author: Piotr Matuszczak piotr.matuszczak@intel.com
Primary assignee: Piotr Matuszczak
Other contributors: Pawel Rapkiewicz pawel.rapkiewicz@intel.com , Kamil Kowalski kamil.kowalski@intel.com
Created: 2019-08-07
The BMC on server platform gathers lots of telemetry data, which has to be exposed in clean, human readable and standardized format. This document focuses on telemetry over the Redfish, since it is standard API for platform manageability.
Redfish Telemetry Model shall implement Telemetry Service with the following collection resources:
OpenBMC telemetry architecture is shown on the diagram below.
+--------------+ +----------------+ +-----------------+ |hwmon| | |Dbus sensors| | |Telemetry| | +-----/ | +------------/ | +---------/ | | +--filesystem---> | | | | | | | | | +--------------+ +--------^-------+ +--------^--------+ | | | | <------------------------------------------v-----^--DBus----------v-----------> | | +-------+---------------------------------------------------------------------+ |bmcweb | | | +-------/ | | | | | | +--------+-------------------------------------v--------------------------+ | | |Redfish | | | | +--------/ +---------+-------+ | | | | |Existing | | | | | | +------------------------------------------------+ |Redfish | | | | | | |Telemetry Service| | |resources| | | | | | +----------------+/ | +---------/ | | | | | | +----------+ +-----------+ +-------------+ | | +---------+ | | | | | | | Metric | | Metric | |Metric report| | | | Redfish | | | | | | | | triggers | |definitions| |definitions <---------+ sensors | | | | | | | | | | | | | | | | | | | | | | | +----+-----+ +-----+-----+ +------+------+ | | +---------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-----v-----+ | | | | | | | | | | | Metric | | | | | | | | | | +--------> report <---------+ | | | | | | | | | | | | | | | | | | +-----------+ | | | | | | | | | | | | | | | +------------------------------------------------+ +-----------------+ | | | | | | | +-------------------------------------------------------------------------+ | | | +-----------------------------------------------------------------------------+
The telemetry service component is a part of Redfish and implements the DMTF's Redfish Telemetry Model. Metric report definitions uses Redfish sensors URIs for metric report creation. Those sensors are also used to get URI->D-Bus sensor mapping. Redfish Telemetry Service acts as presentation layer for the telemetry, while Telemetry service is responsible for gathering metrics from D-Bus sensors and exposing them as D-Bus objects. Telemetry service supports different monitoring modes (periodic, on change and on demand) along with aggregated operations:
The time period for calculating aggregated is taken from the Redfish Metric Definition resource for each sensor's metric.
Telemetry service supports creating and managing metric report, which may contain single or multiple metrics from sensors. This metric report is mapped to Metric Report for the Redfish Telemetry Service.
The diagram below shows the flows for creation and update of metric report.
+----+ +------+ +---------+ +-------+ |User| |bmcweb| |Telemetry| | D-Bus | +-+--+ +--+---+ +----+----+ |Sensors| | | | +---+---+ | | | | +-----------------------------------------------------------------------------+ |Metric report definition flow| | | | +-----------------------------+ | | | | | | | | | | | | | | | | | POST request | | | | | | with metric | | | | | | report | | | | | | definition | | | | | +--------------------> Invoke AddReport | Register for D-Bus | | | | | method on D-Bus | sensors | | | | +-----------------------> PropertiesChanged | | | | | | signals | | | | | +--------------------------> | | | | |--------------------------> | | | | +--------------------------> | | | | | | | | | HTTP response | +-+Create Report | | | | code 201 with | Return created | |D-Bus object | | | | Metric Report | Report D-Bus path <-+ | | | | Definition's URI <-----------------------+ | | | <--------------------+ | | | | | | | | | | | | | | | +-----------------------------------------------------------------------------+ | | | | +-----------------------------------------------------------------------------+ |Periodic metric report update flow| | | | +----------------------------------+ +-+Metric report | | | | | | |timer triggers | | | | | <-+report update | | | | | | | | +----------------------------------Optional-----------------------------------+ | | | | | | | | Send report as SSE or push-style event | | | | | using Redfish Event Service (not shown | | | | | here) if configured to do so. | | | | <--------------------------------------------+ | | | | | | | | +-----------------------------------------------------------------------------+ | | GET on Metric | | | | | | Report URI | | Sensor's Properties- | | | +--------------------> | Changed signal | | | | +-+Map report's URI <--------------------------+ | | | | |to D-Bus path | | | | | <-+ | +----------------------+ | | | | | Invoke GetAll method | |Note that sensor's | | | | | | on report D-Bus | |PropertiesChanged | | | | | | object | |signal is asynchronous| | | | | +-----------------------> |to metric report timer| | | | | | | |This timer is the only| | | | | Return metric | Return report data | |thing that triggers | | | | | report in JSON <-----------------------+ |metric report update | | | | | format | | +----------------------+ | | | <--------------------+ | | | | | | | | | +-----------------------------------------------------------------------------+ | | | | +-----------------------------------------------------------------------------+ |On change metric report update flow| | Sensor's Properties- | | +-----------------------------------+ | Changed signal | | | | | <--------------------------+ | | | | | | | | | | +-+Sensor's signal | | | | | | |triggers report | | | | | <-+update | | | | | | | | +----------------------------------Optional-----------------------------------+ | | | | | | | | Send report as SSE or push-style event | | | | | using Redfish Event Service (not shown | | | | | here) if configured to do so. | | | | <--------------------------------------------+ | | | | | | | | +-----------------------------------------------------------------------------+ | | GET on Metric | | | | | | Report URI | | | | | +--------------------> | | | | | +-+Map report's URI | | | | | | |to D-Bus path | +----------------------+ | | | | <-+ | |Note that sensor's | | | | | | Invoke GetAll method | |PropertiesChanged | | | | | | on report D-Bus | |signal triggers the | | | | | | object | |report update. It is | | | | | +-----------------------> |sufficient that the | | | | | | | |signal from only one | | | | | Return metric | Return report data | |sensor triggers report| | | | | report in JSON <-----------------------+ |update. | | | | | format | | +----------------------+ | | | <--------------------+ | | | | | | | | | +-----------------------------------------------------------------------------+ | | | | +-+--------------------+------------------------------------------------------+ |On demand metric report update flow| | | | +-+--------------------+------------+ | | | | | | | | | | | GET on Metric | | | | | | Report URI | | | | | +--------------------> | | | | | +-+Map report's URI | | | | | | |to D-Bus path | | | | | <-+ | | | | | | | | | | | | Invoke the Update | | | | | | method for report | | | | | | D+Bus object | | | | | +-----------------------> | | | | | +-+Update method triggers | | | | | | |report to be updated | | | | | | |with the latest known | | | | | | |sensor's readings. | | | | | | |No additional sensor | | | | | <-+readings are performed. | | +----------------------------------Optional-----------------------------------+ | | | | | | | | Send report as SSE or push-style event | | | | | using Redfish Event Service (not shown | | | | | here) if configured to do so. | | | | <--------------------------------------------+ | | | | | | | | +-----------------------------------------------------------------------------+ | | | Update method call | | | | | | result | | | | | <-----------------------+ | | | | | | | | | | | Invoke GetAll method | | | | | | on report D-Bus | | | | | | object | | | | | +-----------------------> | | | | | | | | | | Return metric | Return report data | | | | | report in JSON <-----------------------+ | | | | format | | | | | <--------------------+ | | | | | | | | | +-----------------------------------------------------------------------------+ | | | |
The Redfish implementation in bmcweb is stateless, thus it is not able to store metric reports. All operations on metric reports shall be done in the Telemetry service. Sending metric report as SSE or push-style events shall be done via the Redfish Event Service. It is marked as optional because metric report does not have to be configured for pushing its data through the event.
In case of on demand metric report update, Telemetry service performs no additional sensor readings because it already has the latest values, since they are updated on PropertiesChanged signal from the D-Bus sensors.
Telemetry service on D-Bus
Telemetry service exposes specific interfaces on D-Bus. One of them will be used for reading report management. The second one will be used for triggers management.
Reading report management
The reading report management D-Bus object:
xyz.openbmc_project.Telemetry.ReportsManagement /xyz/openbmc_project/Telemetry/Reports
The ReportsManagement supports the following interface apart from standard D-Bus interface.
| Name | Type | Signature | Result/Value | Flags |
|---|---|---|---|---|
xyz.openbmc_project.Telemetry.ReportsManagement | interface | - | - | - |
.AddReport | method | ssuas | s | - |
.MaxReports | property | u | 50 | emits-change |
.PollRateResolution | property | u | 100 | emits-change |
The AddReport method is used to create metric report. The report may contain single or multiple sensor readings. It is stored in the BMC's volatile memory. The method has the following arguments:
| Argument | Type | Description |
|---|---|---|
| Prefix | string | Defines prefix for report so it will be "<prefix><randomString>" i.e.: for prefix "test" -> testqrapndyY |
| ReportingType | string | Reporting type: "xyz.openbmc_project.Telemetry.Metric.Periodic" - For periodic update "xyz.openbmc_project.Telemetry.Metric.OnChange" - For update when value changes "xyz.openbmc_project.Telemetry.Metric.OnRequest" - For update when user requests data |
| ScanPeriod | uint32_t | Scan period used when Periodic type is set (in milliseconds) |
| MetricsParams | array of structures | Collection of metric parameters. |
The MetricParams array entry is a structure containing: | Field | Type | Description | |----------|------|-------------| | Sensor's path | object | D-Bus path, path to the sensor providing readings. | | Operation's type | enum | {SINGLE, MAX, MIN, AVG, SUM} - information about aggregated operation. | | Metric id | string | Contains unique metric id, that can be mapped to Redfish MetricId. |
The ScanPeriod is defined per report, thus all sensors listed in the MetricsParams collection will be scanned wit the same frequency. Also the ReportingType is defined per report. In case when xyz.openbmc_project.Telemetry.Metric.OnChange ReportingType was defined, metric report will emit signal when at least one reading has changed.
The AddReport method returns:
String for created report - ie. '/xyz/openbmc_project/Telemetry/Reports/testqrapndyY'
Such created metric report implements the following interfaces, methods and properties (apart from standard D-Bus interface):
| Name | Type | Signature | Result/Value | Flags |
|---|---|---|---|---|
xyz.openbmc_project.Object.Delete | interface | - | - | - |
.Delete | method | - | - | - |
xyz.openbmc_project.Telemetry.Report | interface | - | - | - |
.Update | method | - | - | - |
.ReadingParameters | property | a(sos) | 1 "/" | emits-change writable |
.Readings | property | a(svs) | 0 | emits-change read-only |
.ReportingType | property | s | One of reporting type strings | emits-change writable |
.ScanPeriod | property | u | 100 | emits-change writable |
The Update method is defined for the on demand metric report update. It shall trigger the Readings property to be updated and send PropertiesChanged signal.
The ReadingParameters property contains an array of structures containing unique metric id, D-Bus sensor path and aggregated operation type. This property is made writable in order to support metric report modifications.
| Field Type | Field Description |
|---|---|
| string | Unique metric id |
| object path | D-Bus sensor's path |
| string | Aggregated operation type |
The Readings property contains the array of the structures containing metric unique id, sensor's reading value and reading timestamp.
| Field Type | Field Description |
|---|---|
| string | Unique metric id |
| variant | Sensor's reading value |
| string | Sensor's reading timestamp |
The ScanPeriod property has single value for the whole metric report. The Delete method results in deleting the whole metric report.
The MaxReports property of the xyz.openbmc_project.Telemetry.ReportsManagement interface contains the max number of metric reports supported by the Telemetry service. This property is added to be compliant with the Redfish Telemetry Service schema, that contains MaxReports property.
Trigger management
The trigger management D-Bus object:
xyz.openbmc_project.Telemetry.TriggersManagement /xyz/openbmc_project/Telemetry/Triggers
The TriggersManagement supports the following interface apart from standard D-Bus interface.
| Name | Type | Signature | Result/Value | Flags |
|---|---|---|---|---|
xyz.openbmc_project.Telemetry.TriggersManagement | interface | - | - | - |
.AddTrigger | method | sssv(os) | s | - |
The AddTrigger method shall be used to create new trigger for the certain metric. Triggers are stored in BMC's volatile memory. The method has the following arguments:
| Argument | Type | Description |
|---|---|---|
| Prefix | string | Defines prefix for report so it will be "<prefix><randomString>" i.e.: for prefix "test" -> trigger0dfvAgVt6 |
| ActionType | string | Action type: "xyz.openbmc_project.Telemetry.Trigger.Log" - For logging to log service "xyz.openbmc_project.Telemetry.Trigger.Event" - For sending Redfish event "xyz.openbmc_project.Telemetry.Trigger.Update" - For trigger metric report update |
| MetricType | string | Metric type: "xyz.openbmc_project.Telemetry.Trigger.Discrete" - for discrete sensors "xyz.openbmc_project.Telemetry.Trigger.Numeric" - for numeric sensors |
| TriggerParams | variant | Variant containing structure with either discrete triggers or numeric thresholds. |
| MetricParam | structure | Structure containing D-Bus sensor's path and unique metric Id and optional D-Bus path to metric report to trigger. |
The TriggerParams is variant type, which shall contain structure depending on the MetricType value. In case when MetricType contains the xyz.openbmc_project.Telemetry.Trigger.Discrete value, TriggerParams shall contain structure with discrete triggers. When MetricType contains the xyz.openbmc_project.Telemetry.Trigger.Numeric value, TriggerParams shall contain structure with numeric thresholds.
Discrete triggers structure:
| Field | Type | Description |
|---|---|---|
| TriggerCondition | string | Discrete trigger condition: "xyz.openbmc_project.Telemetry.Trigger.Discrete.Changed" - trigger ocurs when value of metric has changed; "xyz.openbmc_project.Telemetry.Trigger.Discrete.Specified" - trigger occurs when value of metric becomes one of the values listed in the discrete triggers. |
| DiscreteTriggers | array of structures | Array of discrete trigger structures. |
Member of DiscreteTriggers array:
| Field | Type | Description |
|---|---|---|
| TriggerId | string | Unique trigger Id |
| Severity | string | Severity: "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.OK" - normal, "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.Warning" - requires attention, "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.Critical" - requires immediate attention |
| Value | variant | Value of discrete metric, that constitutes a trigger event. |
| DwellTime | uint64 | Time in milliseconds that a trigger occurrence persists before the action defined in the ActionType is performed. |
Numeric thresholds structure shall contain up to 4 thresholds: upper warning, upper critical, lower warning and lower critical. Thus it will contain up to 4 structures shown below:
| Field | Type | Description |
|---|---|---|
| ThresholdType | string | Numeric trigger type: "xyz.openbmc_project.Telemetry.Trigger.Numeric.UpperCritical","xyz.openbmc_project.Telemetry.Trigger.Numeric.UpperWarning","xyz.openbmc_project.Telemetry.Trigger.Numeric.LowerCritical","xyz.openbmc_project.Telemetry.Trigger.Numeric.LowerWarning" |
| DwellTime | uint64 | Time in milliseconds that a trigger occurrence persists before the action defined in the ActionType is performed. |
| Activation | string | Indicates direction of crossing the threshold value that trigger the threshold's action: "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Increasing", "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Decreasing", "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Either" |
| ThresholdValue | variant | Value of reading that will trigger the threshold |
The numeric threshold trigger type meaning:
The numeric threshold activation meaning:
The MetricParam structure contains the following data:
| Field | Type | Description |
|---|---|---|
| SensorPath | object path | D-Bus path to sensor, for which trigger is defined. |
| MetricId | string | Contains unique metric id, that can be mapped to Redfish MetricId. |
| ReportPath | object path | D-Bus path to Telemetry's reading report which update shall be triggered when trigger condition occurs. This is optional and shall be filled when trigger's ActionType is set to "xyz.openbmc_project.Telemetry.Trigger.Update". |
The AddTrigger method returns:
String for created trigger - ie. '/xyz/openbmc_project/Telemetry/Triggers/trigger0dfvAgVt6'
Such created trigger implements the following interfaces, methods and properties (apart from standard D-Bus interface):
| Name | Type | Signature | Result/Value | Flags |
|---|---|---|---|---|
xyz.openbmc_project.Object.Delete | interface | - | - | - |
.Delete | method | - | - | - |
xyz.openbmc_project.Telemetry.Trigger | interface | - | - | - |
.MetricType | property | s | One of the MetricType strings | emits-change read-only |
.Triggers | property | {sa{ssvu64}} or a{su64sv} | The structure containing triggers. It depends on .MetricType property how the structure is defined. | emits-change writable |
.ActionType | property | s | One of ActionType strings | emits-change writable |
.Metric | property | (oso) | Structure containing details of metric, for which trigger is defined. | emits-change writable |
The .MetricType property contains information about metric type for which trigger was created. It can be either discrete or numeric. This property is read-only, thus created trigger cannot be changed from discrete to numeric or from numeric to discrete. This also determines how the .Triggers property looks like on D-Bus.
If .MetricType is equal to "xyz.openbmc_project.Telemetry.Trigger.Discrete" then .Triggers property contains discrete trigger that looks like this:
| Type | Description |
|---|---|
| string | Discrete trigger condition: "xyz.openbmc_project.Telemetry.Trigger.Discrete.Changed" - trigger ocurs when value of metric has changed; "xyz.openbmc_project.Telemetry.Trigger.Discrete.Specified" - trigger occurs when value of metric becomes one of the values listed in the discrete triggers. |
| array of structures | Array of discrete trigger structures. |
Member of DiscreteTriggers array:
| Type | Description |
|---|---|
| string | Unique trigger Id |
| string | Severity: "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.OK" - normal, "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.Warning" - requires attention, "xyz.openbmc_project.Telemetry.Trigger.Discrete.Severity.Critical" - requires immediate attention |
| variant | Value of discrete metric, that constitutes a trigger event. |
| uint64 | Time in milliseconds that a trigger occurrence persists before the action defined in the ActionType is performed. |
If .MetricType is equal to "xyz.openbmc_project.Telemetry.Trigger.Numeric" then .Triggers property contains numeric trigger that is an array of 4 structures presented below:
| Type | Description |
|---|---|
| string | Numeric trigger type: "xyz.openbmc_project.Telemetry.Trigger.Numeric.UpperCritical", "xyz.openbmc_project.Telemetry.Trigger.Numeric.UpperWarning", "xyz.openbmc_project.Telemetry.Trigger.Numeric.LowerCritical", "xyz.openbmc_project.Telemetry.Trigger.Numeric.LowerWarning" |
| uint64 | Time in milliseconds that a trigger occurrence persists before the action defined in the ActionType is performed. |
| string | Indicates direction of crossing the threshold value that trigger the threshold's action: "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Increasing", "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Decreasing", "xyz.openbmc_project.Telemetry.Trigger.Numeric.Activation.Either" |
| variant | Value of reading that will trigger the threshold |
The .Metric property stores the details about reading, for which trigger was defined. It is in a form of structure consisting of three fields.
| Field type | Description |
|---|---|
| object path | D-Bus path of sensor. This is a path to the sensor, for which reading trigger is defined. |
| string | Unique metric Id |
| object path | D-Bus path of existing reading report. This is required when trigger's action is to update metric report. This path shall point to existing reading report within the Telemetry service. |
Trigger operations
Triggers support three types of operation: Log, Event and Update. For each, there is a different way of proceeding.
+---------------------------+ |bmcweb| | +----------------------+ +------/ +-----------+-+ | |Telemetry| | | |Redfish | | | +---------/ | | |log service| | | | | | +-----------/ | | | | | | | | | | | | | | | | | +------^------+ | +-----------+----------+ +---------------------------+ | | | +----collect----+ event journal entry | (write to journal) | | +------------------------------------+ | |systemd| | | | +-------/ +----------+ +---+------+ | | | |journal| | |libjournal| | | | +-------/ <--> <-------+ | | | +----------+ | | | | | | | | | | +----------+ | | | +------------------------------------+
For action Event, the Telemetry service shall send event using the Redfish Event Service either as push-style event or SSE.
For action Update, the Telemetry service will trigger the update of reading report pointed by it's D-Bus path contained in ReportPath property inside the .Metric structure. The update shall cause the reading report's D-Bus object to emit property change signal. This will cause Redfish Metric Report to be streamed out if it was configured to do so.
Redfish Telemetry Service API
Redfish Telemetry Service shall support 2019.1 Redfish schemas for telemetry resources. Metric report definitions determines which metrics are to be include in metric report. Metric definition is assigned to particular metric type and it describes how the metric should be interpreted. The following resource schemas shall be supported:
The following diagram shows relations between these resources.
+----------------------------------------------------------------------------+ | Service root | +----------------------------------+-------------------------------+---------+ | | | | | | +----------------------------------v-----------------+ +----------v---------+ | | |Chassis | | Telemetry Service | | | | | | | | | | +---------------+ | +---------+--------------+------------------+--------+ | | | | | | | | | Chassis 1 | | | | | | | | | | | | | +---------+-----+ | | | | | | | +----------v--+ +--------v----+ +----------v-----+ +--------------------+ |Triggers | |Metric | |Metric report | | | | |definition | | | | | | | +---------+ | | | Reads | | +---------+ | | |Reading | | | +-----------+ | ReadingVolts +--v------+ | | | | | |Volts <------+ +------------------> | | |Trigger 1| | | +---------+ | | | Metric | | | | | | | | | | | | report 1 | | Reads | Power | | | | | | +---------+ | | | | | PowerConsumed | | | | | | | | | | | | | | Watts | | | +--+---+--+ | | |Power <------+ +------------------> | | | | | | |Consumed | | | +-----^-----+ | +----^----+ | | | | | |Watts | | | | | | | | | | | +---------+ | | | | | | | | | | | | | | | +-------------+ +-------------+ +----------------+ | | | | | | | Triggers report update | | | | (when applicable) | | | +--------------------------------+ | | | | Monitors PowerConsumedWatts to check | | whether trigger value is exceeded | +------------------------------------------------------------------+
The diagram shows the relations between Redfish resources. Metric report is defined to be generated periodically, on demand or on change. Each metric in the Metric Report contains the URI to its metric definition and Redfish sensor, which reading value is presented. Nevertheless, under this presentation layer, Telemetry is gathering D-Bus sensors readings and exposing them in reading reports over D-Bus for the Telemetry Service. Each D-Bus sensor is mapped to Redfish sensor.
Below examples of Redfish resources for the Telemetry Service are shown.
The Telemetry Service Redfish resource example:
{ "@odata.type": "#TelemetryService.v1_1_2.TelemetryService", "Id": "TelemetryService", "Name": "Telemetry Service", "Status": { "State": "Enabled", "Health": "OK" }, "MinCollectionInterval": "T00:00:10s", "SupportedCollectionFunctions": [], "MaxReports": <max_no_of_reports>, "MetricDefinitions": { "@odata.id": "/redfish/v1/TelemetryService/MetricDefinitions" }, "MetricReportDefinitions": { "@odata.id": "/redfish/v1/TelemetryService/MetricReportDefinitions" }, "MetricReports": { "@odata.id": "/redfish/v1/TelemetryService/MetricReports" }, "Triggers": { "@odata.id": "/redfish/v1/TelemetryService/Triggers" }, "LogService": { "@odata.id": "/redfish/v1/Managers/<manager_name>/LogServices/Journal" }, "@odata.context": "/redfish/v1/$metadata#TelemetryService", "@odata.id": "/redfish/v1/TelemetryService" }
Sample metric report definition:
{ "@odata.type": "#MetricReportDefinition.v1_3_0.MetricReportDefinition", "Id": "SampleMetric", "Name": "Sample Metric Report Definition", "MetricReportDefinitionType": "Periodic", "Schedule": { "RecurrenceInterval": "T00:00:10" }, "ReportActions": [ "LogToMetricReportsCollection" ], "ReportUpdates": "Overwrite", "MetricReport": { "@odata.id": "/redfish/v1/TelemetryService/MetricReports/SampleMetric" }, "Status": { "State": "Enabled" }, "Metrics": [ { "MetricId": "Test", "MetricProperties": [ "/redfish/v1/Chassis/NC_Baseboard/Power#/PowerControl/0/PowerConsumedWatts" ] } ], "@odata.context": "/redfish/v1/$metadata#MetricReportDefinition.MetricReportDefinition", "@odata.id": "/redfish/v1/TelemetryService/MetricReportDefinitions/PlatformPowerUsage" }
Sample metric report:
{ "@odata.type": "#MetricReport.v1_2_0.MetricReport", "Id": "SampleMetric", "Name": "Sample Metric Report", "ReportSequence": "0", "MetricReportDefinition": { "@odata.id": "/redfish/v1/TelemetryService/MetricReportDefinitions/SampleMetric" }, "MetricValues": [ { "MetricDefinition": { "@odata.id": "/redfish/v1/TelemetryService/MetricDefinitions/SampleMetricDefinition" }, "MetricId": "Test", "MetricValue": "100", "Timestamp": "2016-11-08T12:25:00-05:00", "MetricProperty": "/redfish/v1/Chassis/Tray_1/Power#/0/PowerConsumedWatts" } ], "@odata.context": "/redfish/v1/$metadata#MetricReport.MetricReport", "@odata.id": "/redfish/v1/TelemetryService/MetricReports/AvgPlatformPowerUsage" }
Sample trigger, that will trigger metric report update:
{ "@odata.type": "#Triggers.v1_1_1.Triggers", "Id": "SampleTrigger", "Name": "Sample Trigger", "MetricType": "Numeric", "Links": { "MetricReportDefinitions": [ "/redfish/v1/TelemetryService/MetricReportDefinitions/SampleMetric" ] }, "Status": { "State": "Enabled" }, "TriggerActions": [ "RedfishMetricReport" ], "NumericThresholds": { "UpperCritical": { "Reading": 50, "Activation": "Increasing", "DwellTime": "PT0.001S" }, "UpperWarning": { "Reading": 48.1, "Activation": "Increasing", "DwellTime": "PT0.004S" } }, "MetricProperties": [ "/redfish/v1/Chassis/Tray_1/Power#/0/PowerConsumedWatts" ], "@odata.context": "/redfish/v1/$metadata#Triggers.Triggers", "@odata.id": "/redfish/v1/TelemetryService/Triggers/PlatformPowerCapTriggers" }
Performance tests
Performance test were conducted on the AST2500 system with 64 MB flash and 512 MB RAM. Flash consumption by the Telemetry service is 197.5 kB. The runtime statistics are shown in the table below. The reading report is mapped into single Metric Report. The runtime data is collected for the Telemetry component only. All reports was created with xyz.openbmc_project.Telemetry.Metric.OnChange property to maximize the workload. In the configuration with 50 reports and 50 sensors it is about 200 new readings per second, generating 200 reading reports per second. The table shows CPU usage and memory usage. The VSZ is the amount of memory mapped into the address space of the process. It includes pages backed by the process' executable file and shared libraries, its heap and stack, as well as anything else it has mapped.
| Telemetry service state | VSZ | %VSZ | %CPU |
|---|---|---|---|
| Idle (0 reports, 0 sensors) | 5188 B | 1% | 0% |
| 1 report, 1 sensor | 5188 B | 1% | 1% |
| 2 reports, 1 sensor | 5188 B | 1% | 1% |
| 2 reports, 2 sensors (1 sensor per report) | 5188 B | 1% | 1% |
| 1 report, 10 sensors | 5188 B | 1% | 1% |
| 10 reports, 10 sensors (same for each report) | 5320 B | 1% | 1-2% |
| 2 reports, 20 sensors (10 per report) | 5188 B | 1% | 1% |
| 30 reports, 30 sensors (10 per report) | 5444 B | 1% | 5-9% |
| 50 reports, 50 sensors (10 per report) | 5572 B | 1% | 11-14% |
The last two configurations use 10 sensors per reading report, which gives 3 or 5 distinctive configurations. Each such configuration is used to create 10 reading reports to obtain the desired amount of 30 or 50 reading reports.
In this architecture reading report is created every time when Redfish Metric Report Definition is posted (creating new Metric Report).
The framework based on collectd/librrd was considered as alternate design. Although it seems to be versatile and scalable solution, it has some drawbacks from our point of view:
Since this design assumes flexibility and modularity, there is no obstacles to use collectd in cooperation with Telemetry. The one of possible configurations is shown on the diagram below.
+-----------------+ +-----------------+ | D-Bus sensors | | Telemetry | +--------^--------+ +--------^--------+ | | | | | | <--------^--v-----------D-Bus--------v-^----------> | | | | | | +-------v------------+ +----------v--------+ | collectd metrics | | | | exposed as D-Bus | | bmcweb | | sensors | | (with Redfish | +---------^----------+ | Telemetry | | | Service) | | | | +------+-------+ +-------------------+ | | | collectd | | | +--------------+
Here collectd is used as the source of some set of metrics. It exposes them as the D-Bus sensors, which can easily be consumed either by the bmcweb and Telemetry service without any changes in their D-Bus interfaces. In such configuration Telemetry service provides metric reports and triggers management.
Other possible configuration is to use collectd without the Telemetry service, but in such case, collectd does not provide metric reports and triggers support compatible with the Redfish. In such case, Redfish Telemetry Service won't be supported or metric reports and triggers support has to be provided by the collectd.
This design impacts the architecture of the bmcweb component, since it adds the Redfish Telemetry Service implementation as a component for the existing Redfish API implementation.
This is the very high-level description of the proposed set of tests. Testing shall be done on three basic levels:
Unit tests
The Telemetry's code shall be covered by the unit tests. The preferred framework is the GTest/GMock. The unit tests shall be ran before code change is to be committed to make sure, that nothing is broken in existing functionality. Also, when new code is introduced, a new set of unit tests shall be committed with it according to test-driven development principle. Unit tests shall be also carefully reviewed.
Functional tests
Functional tests will be divided into two steps.
First step is for testing the Telemetry metric reports management. Test scenario shall contain creating metric report by POSTing proper metric report definition, reading metric report (using GET on proper URI) and deleting the metric report. The required configuration for such test is D-Bus sensors (at least some of them) and bmcweb with Redfish Telemetry Service implemented. The tests shall be performed on real hardware. For ease of metric testing, dummy D-Bus sensors may be provided to provide specifically prepared metrics. This configuration shall also enable testing aggregated operations (MIN, MAX, SUM, AVG).
Second step is to test triggers and events generation. This will require also Event Service to be implemented along with Log Service. Tests shall cover all scenarios with sending metric report as an event, triggering metric report update and logging events.
Performance tests
Performance tests shall be done using full OpenBMC configuration with all the required set of features. The tests shall create a lot of metric reports (up to maximum number) along with all possible triggers. Measurements shall cover the periodic metric report jitter, delays in event logging or sending, BMC's CPU utilization and the performance impact on other services.