ZabbixSender: match zabbix_sender command line tool behaviour regarding metric 'host' attribute

[m-khvoinitsky]

• ZabbixSender: add agent_hostname option, read it from config if enabled
• if ZabbixMetric host attribute is None or '-', use aforementioned value from ZabbixSender

Related zabbix_sender documentation (see -i, --input-file input-file paragraph).

[coveralls]

Pull Request Test Coverage Report for Build 343

• 8 of 8 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 90.062%

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Totals
Change from base Build 331:	0.2%
Covered Lines:	290
Relevant Lines:	322

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💛 - Coveralls

[m-khvoinitsky]

Anyone?

[adubkov]

Thanks for your contribution. I reviewed your pull request and I don't think we should add agent_hostname as separate class attribute. It should be set up as part of use_config. Otherwise this may break code for many people.

What we should do is following:

1. Modify _load_from_config function to set properties directly via self and return not None value on error.
2. Update __init__ to:

self.agent_hostname = None
self.zabbix_uri = [(zabbix_server, zabbix_port)]

if use_config:
   assert self._load_from_config(use_config) == None, "error occurred during loading zabbix agent config"

3. When formatting metrics use agent_hostname only if metric hostname is '' and if it was loaded from config:

for m in metrics:
    if m.host == '' and self.agent_hostname:
        m.host = self.agent_hostname
 ....