mgmt: hawkbit: define attributes in the user application

[maass-hamburg]

Attributes can now be defined in the user application by the use of a callback function.
Resolves: #37640

[maass-hamburg]

ping

[maass-hamburg]

ping @ycsin

[maass-hamburg]

just a rebase to the current main

[ycsin]

I haven't really looked at this in details yet but it seems to expose a little too much to the public than I would like, i.e. all the structs and stuff that used to be internal.

I wonder if it is possible to just have a mechanism for hawkBit to get the formatted json of the attributes from the app in the form of a buffer and sent it to the server?

[maass-hamburg]

I haven't really looked at this in details yet but it seems to expose a little too much to the public than I would like, i.e. all the structs and stuff that used to be internal.

they are needed if the user wants to define its own config callback. but maybe they could be put in a seperate header file and not in include/zephyr/mgmt/hawkbit.h maybe include/zephyr/mgmt/hawkbit_config.h or create a new folder include/zephyr/mgmt/hawkbit/ which contains include/zephyr/mgmt/hawkbit/hawkbit.h and include/zephyr/mgmt/hawkbit/config.h ?

I wonder if it is possible to just have a mechanism for hawkBit to get the formatted json of the attributes from the app in the form of a buffer and sent it to the server?

It might be, but then we can't use the json library to encode struct json_obj_descr json_cfg_descr, only for struct json_obj_descr json_cfg_data_descr. As it is currently not possible to add a already encoded object to a json_obj_descr.

[maass-hamburg]

I wonder if it is possible to just have a mechanism for hawkBit to get the formatted json of the attributes from the app in the form of a buffer and sent it to the server?

@ycsin with a change of the json lib it is possible

[maass-hamburg]

The approach in this PR should work, I just wonder if we can keep the default implementation simple (only send device_id) but provide more flexibility by having a mechanism (another step or public function, if enabled) to "merge" any custom attributes to the record in the server, i.e. the reason of last reboot (reset cause), die temp, stack watermark, ...

This problem is that the device attributes are only send to the server if the server requests it. This normally only happens once. the hawkBit server will only request it again, if you go in the user interface and click there on Request attributes update. It could be done to send it without the server requesting but that's outside of the scope of this PR .

[ycsin]

This patch works - Have you considered doing this kind of one time configurations during hawkbit_init by extending it to accept an config struct? The same idea can also applies to #68806

[maass-hamburg]

This patch works - Have you considered doing this kind of one time configurations during hawkbit_init by extending it to accept an config struct? The same idea can also applies to #68806

I would prefer to not do it that way, as most subsystems in zephyr are also using this separate approach when it comes to setting callbacks.

[ycsin]

The doc can use some improvements, LGTM in general

[maass-hamburg]

rebased to resolve conflicts

[ycsin]

Re-ack

[carlescufi]

LGTM