Modern event logs in OpenBMC
Current Status
I’ve been working on implementations of revamped event log design and wanted to give an update as to the current implementation progress.
Currently, the definition of the YAML format and event logging has been
implemented through sdbusplus, phosphor-dbus-interfaces, and
phosphor-logging; new errors can be defined in PDI and phosphor-logging can be
called to record them. There is also a handy CLI tool written that allows users
to mock events.
The following items are to be worked in the near future:
- Allow-list / Block-list support in
phosphor-logging. - Changing
AdditionalDatato be a dictionary. - Generation of the Redfish Message Registry.
- Translation in
bmcwebofphosphor-loggingevents to proper RedfishLogEntryformat, including populatingMessageArgs. - Adding ‘Hint’ support in
Logging.Create.
Defining a new Event
Defining a new event requires writing an events.yaml file in PDI. Two decently
featured examples are currently available: Sensor Thresholds
(exclusively using standard Redfish events) and Leak Detector
(defining OpenBMC-specific events).
Rather than doing custom sanity parsing of these YAML files, as was done for the
sdbusplus interface definitions, I am leveraging JSON-Schema.
This allows pretty decent explanation when the YAML file doesn’t meet
expectations; I may add this capability to the interface YAML files at some
point.
From the YAML, sdbusplus will generate a C++ class for an event. This class
can either be thrown, which is useful for sdbusplus servers that want the event
to be sent back as part of the dbus response, or “committed” to
the phosphor-logging record. The commit APIs support both blocking and async
variants.
See this test-case as an example:
path = co_await lg2::commit(data->client_ctx,
LoggingCleared("NUMBER_OF_LOGS", 6));
In the above code it might be noticed that the event metadata is taken as
{string, data} pairs. There is compile-time checking to ensure the correct
metadata has been provided.
### Missing metadata
../test/log_manager_dbus_tests.cpp:131:32: error: no matching function for call to ‘sdbusplus::event::xyz::openbmc_project::Logging::Cleared::Cleared()’
131 | { throw LoggingCleared(); }, LoggingCleared);
### Incorrect metadata name
../subprojects/sdbusplus/include/sdbusplus/utility/consteval_string.hpp: In member function ‘virtual void phosphor::logging::test::TestLogManagerDbus_GenerateSimpleEvent_Test::TestBody()’:
../test/log_manager_dbus_tests.cpp:130:5: in ‘constexpr’ expansion of ‘sdbusplus::utility::consteval_string<sdbusplus::utility::details::consteval_string_holder<15>{"NUMBER_OF_LOGS"}>("LOGS")’
../subprojects/sdbusplus/include/sdbusplus/utility/consteval_string.hpp:41:25: error: call to non-‘constexpr’ function ‘static void sdbusplus::utility::consteval_string<V>::report_error(const char*) [with consteval_string_holder<...auto...> V = sdbusplus::utility::details::consteval_string_holder<15>{"NUMBER_OF_LOGS"}]’
41 | report_error("String mismatch; check parameter name.");
### Incorrect metadata type
../test/log_manager_dbus_tests.cpp:131:50: error: invalid conversion from ‘const char*’ to ‘uint64_t’ {aka ‘long unsigned int’} [-fpermissive]
131 | { throw LoggingCleared("NUMBER_OF_LOGS", "string"); }, LoggingCleared);
| ^~~~~~~~
| |
| const char*
Using the CLI
I also wrote a log-create CLI which is useful for testing events, which is now
installed by the phosphor-logging package. Running log-create --list will
enumerate all of the event types that phosphor-logging is aware of:
$ log-create --list
Known events:
xyz.openbmc_project.Logging.Cleared
xyz.openbmc_project.Sensor.Threshold.InvalidSensorReading
...
Individual events can be created by specifying the event name and passing the metadata as JSON (if any metadata is required):
$ log-create \
xyz.openbmc_project.Sensor.Threshold.ReadingAboveUpperSoftShutdownThreshold \
--json '{ "SENSOR_NAME": "Inlet Temperature", "READING_VALUE": 98.6, "UNITS": "xyz.openbmc_project.Sensor.Value.Unit.DegreesC", "THRESHOLD_VALUE": 40 }'
This will result in an event such as (some interfaces and fields pruned):
$ busctl --user introspect xyz.openbmc_project.Logging /xyz/openbmc_project/logging/entry/1 -l
xyz.openbmc_project.Logging.Entry interface - - -
.GetEntry method - h -
.AdditionalData property as 8 "READING_VALUE=98.6" "SENSOR_NAME=\"Inlet Temperature\"" "THRESHOLD_VALUE=40.0" "UNITS=\"xyz.openbmc_project.Sensor.Value.Unit.DegreesC\"" "_CODE_FILE=../log_create_main.cpp" "_CODE_FUNC=int generate_event(const std::string&, const nlohmann::json_abi_v3_11_2::json&)" "_CODE_LINE=34" "_PID=1931265" emits-change writable
.EventId property s "" emits-change writable
.Id property u 1 emits-change writable
.Message property s "xyz.openbmc_project.Sensor.Threshold.ReadingAboveUpperSoftShutdownThreshold" emits-change writable
.Resolution property s "" emits-change writable
.Resolved property b false emits-change writable
.ServiceProviderNotify property s "xyz.openbmc_project.Logging.Entry.Notify.NotSupported" emits-change writable
.Severity property s "xyz.openbmc_project.Logging.Entry.Level.Critical" emits-change writable
.Timestamp property t 1732137165521 emits-change writable
.UpdateTimestamp property t 1732137165521 emits-change writable