Make default config option platform independent.

[ruflin]

Currently we have in libbeat platform specific code based on where to look for the log file: https://github.com/elastic/libbeat/blob/master/cfgfile/cfgfile.go#L32

I suggest that we set the same directory as the binary to the default location and configure platform specific directories with the -c flag in the startup service scripts.

This will make it possible to download a binary with a config and start it also without the -c flag by default. This is similar to elasticsearch which checks the file in the config directory.

For reference see also discussion here: https://github.com/elastic/libbeat/pull/341#issuecomment-160987964

[monicasarbu]

I think it's a good idea to solve the problem this way, by looking in the same directory (in the etc directory?) by default and set -c option in the startup service scripts. We can then delete the check from the cfgfile.go.

[monicasarbu]

Kibana & Elasticsearch keep the configuration files under config. We can also rename the etc directory to config to be similar.

[ruflin]

@monicasarbu I like the idea of renaming it to config especially as it is consistent elasticsearch. Renaming the etc. directory will bring naming conflicts but is definitively doable. The less nice part is that currently our download has 3 files, afterwards it would be 1 binary + folder with 2 files (config and template)? Still +1 on this change.

[andrewkroh]

The default config file location is now platform independent. It looks in the directory where the beat binary lives for a <beatname>.yml. No changes were made to add a config.