custom metrics paths, configurable timeouts, newer alpine base, and d…

…ocker user change

json logging, WebIdentity, merge ordering, remote_read fixes, and COR…

…S support

alpine base, log for slow config load, default compression to serverg…

…roups, and fix empty result merging

support only servergroup label matchers

subquery support

swap glog implementation

fix rules reloading

Fix lookbackDelta and offset for VectorSelectors