sr cleanup is too dangerous

[benlapETS]

This option is dangerous if involuntary triggered in an operational environment, we may want to add a switch.

[petersilva]

this bug mostly affects pxatx, which is running 2.17 or earlier... all other systems have explicit protection for xpublic, which is the biggest problem. However sr.py is rewritten in #174, and in there, there is no implementation of sr cleanup (it has been removed.)

losing the function is actually an intermediate step. The rewritten sr.py creates a global state data structure, which makes it possible to do a safe version of cleanup (because it looks at all configurations, not just one at a time) and will delete only if none of the configs reference the exchange. This will help with exchanges that don´t have a special name, like xwinnow, etc... that might fall victim to the same symptom.

So there are some necessary steps to making sr cleanup safe, using the new implementation:

• add/ensure there is a means (in admin.conf?) to declare exchanges that are not used by any local configs to protect them from clean up declare exchange hoho in admin.conf should protect it.

• add parsing of exchanges to the parser in the new sr.py, to know which exchanges should exist.

• add interrogation of state of broker to sr.py to get a global broker state in one data structure (all exchanges, queues, and bindings.)

[petersilva]

note we have had two occurrences of deletion of bindings on xpublic on important pumps, and this caused considerable havoc. however current versions explicitly exclude xpublic from cleanup. so the severity of the defect at this time is not high.

[petersilva]

The declare should likely also use the logic above... the current implementation from #174 still spawns processes to do declare, getting global state as above would allow for a much improved declare.

[petersilva]

implemented new config parse for sr.py on issue187 branch.

[petersilva]

dev for this is on https://github.com/MetPX/sarracenia/tree/issue187

[petersilva]

• --dangerWillRobinson=X must match number of configs to change... what should sr3 --dangerWillRobinson remove do? #827
• deleting exchanges only happens when there are no bindings now sr cleanup deleting exchanges when it should not. #382