Werk #12500: Call parse function even for empty data

Component Checks & agents
Title Call parse function even for empty data
Date Apr 6, 2021
Checkmk Editon Checkmk Raw (CRE)
Checkmk Version 2.1.0i1 2.0.0p2
Level Trivial Change
Class Bug Fix
Compatibility Incompatible - Manual interaction might be required

This change only affect users with own SNMP section plugins developed against the *new* API.

Previously the parse function of an SNMP section (or SNMP check plugin) has only been called if at least *some* data could be fetched from the host (the SNMP device).

In the old API (Checkmk version

The new API will *allways* call the parse function, if the sections raw data is present in the fetched data (even if it is empty). It is the programmers responsibility to deal with an potentially empty data set.

This allows for a subtle distiction: If the parse function returns `None`, no further processing is done, it is regarded as 'not present'. An empty return value could represent some valid information, such as an empty list of error messages.

Note that this behaviour is consistent with the TCP data sources' sections, where we also may encounter sections that are present, but empty.

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