placement

type Config struct {
	Constraints []*Constraint
}

type Constraint struct {
	Function string   // One of "count", "label_values", "count_leader", "isolation_level".
	Filters  []Filter // "key:value" formed parameters.
	Labels   []string // "key" formed parameters.
	Op       string   // One of "<", "<=", "=", ">=", ">".
	Value    int      // Expected expression evaluate value.
}

type Filter struct {
	Key, Value string
}