Add exprfilterprocessor skeleton

[pmcollins]

Description: Adds an exprfilterprocessor skeleton.

Testing: Unit tests added.

[codecov]

Codecov Report

Merging #1844 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1844      +/-   ##
==========================================
- Coverage   91.29%   91.29%   -0.01%     
==========================================
  Files         273      275       +2     
  Lines       16365    16387      +22     
==========================================
+ Hits        14940    14960      +20     
- Misses        998      999       +1     
- Partials      427      428       +1     

Impacted Files	Coverage Δ
processor/exprfilterprocessor/factory.go	100.00% <100.00%> (ø)
processor/exprfilterprocessor/processor.go	100.00% <100.00%> (ø)
translator/internaldata/resource_to_oc.go	87.23% <0.00%> (-2.13%)	⬇️

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[pmcollins]

contribtest failure appears unrelated to this change

[pmcollins]

Any thoughts on a name for this package and processor @keitwb and @jrcamp? typeStr filter and package filterprocessor are taken. Do we want to use labelfilter/labelfilterprocessor or use something else like expfilter/expfilterprocessor?

[keitwb]

It should also be able to filter on metric name so I would avoid calling it label anything. Also this is basically a datapoint filter in the end right or would it also be expanded to work with logs/traces?

[pmcollins]

It should also be able to filter on metric name so I would avoid calling it label anything. Also this is basically a datapoint filter in the end right or would it also be expanded to work with logs/traces?

Yeah I have the same reservations about label. It's just a datapoint filter and I'm not aware of plans to expand to logs or traces, or whether it would be useful to have a multi-purpose filter. So... datapointfilter? :-) cc: @bogdandrutu @tigrannajaryan

[pmcollins]

Renamed to exprfilter.

[rmfitzpatrick]

Would you be able to provide a readme with what this intends to accomplish/provide? Is this an implementation of #560?

edit: see it was removed w/ 4ecdce3. I think providing some context in this diff would be helpful though.

[tigrannajaryan]

@pmcollins yes, please provide the context of the change, what's the goal. Also, if this is a POC I suggest to move this to contrib repo.

[pmcollins]

Would you be able to provide a readme with what this intends to accomplish/provide? Is this an implementation of #560?

edit: see it was removed w/ 4ecdce3. I think providing some context in this diff would be helpful though.

Yeah, we're going in a different direction than the proposal in the first readme so I deleted it. The design has been somewhat in flux but I'll capture what we have in a new readme.

[pmcollins]

@pmcollins yes, please provide the context of the change, what's the goal. Also, if this is a POC I suggest to move this to contrib repo.

Have been working with Ben and Jay who know the context, but will add a readme and move to contrib.