add additional scrape from the CONFIG_DIRS

[Munchery-DavidMichon]

I tried unsuccessfully to add additional scrape from the CONFIG_DIRS following this documentation

It seems that this method InsertScrapesFromDir is never called.
https://github.com/vfarcic/docker-flow-monitor/blob/0a4cc1de4d15f3fbd06fbfd99d9b4eecf824dcaa/prometheus/config.go#L142

[thomasjpfan]

@Munchery-DavidMichon Thanks for bringing this up. I am looking into it.

[thomasjpfan]

The CONFIGS_DIR feature is added in dockerflow/docker-flow-monitor:2-18.05.31-4.

[Munchery-DavidMichon]

@thomasjpfan Thanks it fixes the issue and it's working properly. There's however an error appearing in the log, and this for every file_sd_configs.

level=error ts=2018-05-31T14:38:08.049286094Z caller=file.go:328
component="discovery manager scrape" discovery=file msg="Error reading file"
path=/etc/prometheus/file_sd/monitor_node-exporter.json err="unexpected end of JSON input"