Add goal/design thoughts

README.md

 # lumberjack
 
 Collect logs locally in preparation for processing elsewhere!
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+Problem: logstash jar releases are too fat for constrained systems.
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+Goal: Something small, fast, and light-weight to ship local logs externally.
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+## Design
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+* minimal resources
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+Simple inputs only:
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+* follow files, respect rename/truncation conditions
+* local sockets
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+Simple outputs only:
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+* custom wire event protocol (TBD)