# Functions

MergeLabels merges two maps of labels.
NewNginxCollector creates an NginxCollector.
NewNginxPlusCollector creates an NginxPlusCollector.
NewVariableLabels creates a new struct for VariableNames for the collector.

# Structs

NginxCollector collects NGINX metrics.
NginxPlusCollector collects NGINX Plus metrics.
VariableLabelNames holds all the variable label names for the different metrics.

# Interfaces

LabelUpdater updates the labels of upstream server and server zone metrics.