[Pulp-list] Feedback on sync_repo() result reporting for v2 plugins

[Nick Coghlan]

Based on the current status of the v2 APIs, I now have some working 
rsync-based importer plugins up and running:

http://git.fedorahosted.org/git/?p=pulpdist.git;a=blob;f=src/pulpdist/pulp_plugins/importers/pulpdist_importers/importer.py

(If you want to look at the code for the sync operations themselves, 
they're in pulpdist.core: 
http://git.fedorahosted.org/git/?p=pulpdist.git;a=blob;f=src/pulpdist/core/sync_trees.py)

However, I think the error reporting API leaves a bit to be desired as 
it currently stands. I'd like to be able to raise an exception to 
indicate a problem, but provide additional details in the result as 
structured data.

Currently, I jam everything I want to report into an exception message:

     except:
         et, ev, tb = sys.exc_info()
         msg_format = (
             "exception: {0}\n"
             "error_message: {1}\n"
             "traceback:\n{2}\n"
             "log_details:\n{3}\n"
         )
         raise RuntimeError(msg.format(et, ev,
                            traceback.format_tb(tb),
                            sync_log.getvalue()))

I'd prefer it if I could do something more like what I'm able to do in 
the success case via sync_conduit.build_report():

     except:
         et, ev, tb = sys.exc_info()
         err_summary = {
             "result": command.SYNC_FAILED
             "exception": str(et)
             "message": str(ev)
         }
         err_details = {
             "sync_log": sync_log.getvalue()
             "traceback": traceback.format_tb(tb)
         }
         raise sync_conduit.sync_error(err_summary, err_details)

If I had that richer API, I could also correctly report SYNC_PARTIAL as 
an error without losing data by replacing the current build_report() 
call with the following:

     if result == command.SYNC_PARTIAL:
         raise sync_conduit.sync_error(summary, details)
     else:
         report = sync_conduit.build_report(summary, details)

Regards,
Nick.

-- 
Nick Coghlan
Red Hat Engineering Operations, Brisbane