Redfish EventService Implementation

[Ratan Gupta]

Hi James/Apparao/Brad,

I am inclining towards having a separate application for Redfish 
Logs(like: phosphor-sel-logger),
This application does the following.

1) Have the mapping info from Redfish resources to Dbus Resources
      * This is needed as webserver have to provide the event filtering 
through Resource Type
      * eg : Redfish Client may ask as the client is interested in 
"Account" Resource type
             i.e all the user account related updates should be given to 
redfish client.
             which suggest that there should be mapping from Redfish 
Resource to Dbus Resource

2) Have the reverse mapping from Dbus Resources to Redfish Resources
      * This is needed to send the Redfish event if there is any changes 
in the
        corresponding D-bus resources. eg BMC state change/network 
change etc.

3) This application monitors the D-bus event and Log the event in the 
journal like below
     eg:
         sd_journal_send("MESSAGE=%s", "Account Modified",
             "PRIORITY=%i", LOG_INFO, "REDFISH_MESSAGE_ID=%s",
"REDFISH_RESOURCE_PATH=/redfish/v1/AccountService/accounts/<id>",
             "REDFISH_RESOURCE_TYPE=ComputerSystem"
             "REDFISH_REGISTRY_PREFIX=Task/Base/Resource/Oem",
             "REDFISH_MESSAGE_ARGS=%s", "Off", NULL);

4) rsyslogd will put all these logs from journal into "/var/log/redfish" 
file.

5) bmcweb/webserver would inotify this file location and on notification 
it will send redfish event

6) Event filtering would be done at the bmcweb/webserver side.


We already have the infrastructure for seq no 4 and seq no 5 and we 
wanted to leverage this infrastructure.

Please let me know if there is any concern with this approach.

Ratan

On 6/9/20 6:28 AM, James Feist wrote:
> On 6/8/2020 2:08 PM, Brad Bishop wrote:
>> On Sat, 2020-02-01 at 02:23 +0530, RAJESWARAN THILLAIGOVINDAN wrote:
>>> Hi,
>>>
>>> I am going through the bmcweb code for implementing Redfish
>>> EventService based on the design document
>>> https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/24749. This design
>>> is hooked to the journal based Redfish Event Logging.
>>
>> Would anyone else be willing to opine on whether or not they think
>> journal based event schemes are what we want going forward for OpenBMC?
>>
>> My feeling is that they are not - as an alternative IPC mechanism don't
>> we end up re-implementing things that DBus already does? Doesn't it
>> require us to raise the same event twice everywhere (Once with DBus, and
>> once in the journal)?  What does journal based eventing do that DBus
>> signals don't do?
>
> We don't host log events on DBus at all, so there is no duplicate. The 
> journal gives built in persistence and rotating of logs for large 
> number of events. I know when this came up the last time one of the 
> big issues was supporting thousands of logs wouldn't work well on DBus.
>
>
>>
>> Please poke holes.
>>
>> thx - brad
>>