Rename the settings whose names do not say what they control (closes #234)

Applies the setting renames of the naming audit under the SWW_WAF_ and
SWW_RPROXY_ prefixes, with sneak's names for the IP reputation cache
time and the two time limits, which now take milliseconds. The rproxy
log field default_disposition becomes waf_backend_no_answer, and
config.Config and config.FromEnvironment become config.WAF and
config.WAFFromEnvironment. Go fields, test names and prose follow. No
aliases; nothing reads the old names.

Model: opus-5-5

internal/metrics/metrics.go

@@ -61,12 +61,12 @@ type Metrics struct {
 }
 
 // New returns the metrics, with the Go runtime's and the process's own.
-// topN is how many countries and how many AS numbers get series of their
-// own (SWW_WAF_METRICS_TOP_N). Every metric carries instanceName
-// (SWW_WAF_INSTANCE_NAME) as its label instance.
+// busiestCount is how many countries and how many AS numbers get series of
+// their own (SWW_WAF_METRICS_BUSIEST_COUNTRIES_AND_ASNS). Every metric
+// carries instanceName (SWW_WAF_INSTANCE_NAME) as its label instance.
 //
 //nolint:funlen // a few lines for each metric, a list that grows with them
-func New(topN int, instanceName string) *Metrics {
+func New(busiestCount int, instanceName string) *Metrics {
 	byStatus := []string{"status_class", "action"}
 	byFile := []string{"file"}
 	registry := prometheus.NewRegistry()
@@ -102,7 +102,7 @@ func New(topN int, instanceName string) *Metrics {
 		}),
 		rateLimitHits: counterVec(
 			"sww_rate_limit_hits_total",
-			"Requests that broke a rate limit, a byte limit or the error burst, by "+
+			"Requests that broke a rate limit, a byte limit or the refusal limit, by "+
 				"its window and its kind, requests, bytes or refusals.",
 			[]string{"window", "kind"},
 		),
@@ -114,8 +114,8 @@ func New(topN int, instanceName string) *Metrics {
 				"and the rule's id.",
 			[]string{"mode", "rule_id"},
 		),
-		countries: newCountries(topN),
-		asns:      newASNs(topN),
+		countries: newCountries(busiestCount),
+		asns:      newASNs(busiestCount),
 		GeoJSRequests: prometheus.NewCounter(prometheus.CounterOpts{
 			Name: "sww_geojs_requests_total",
 			Help: "Requests to GeoJS.",
@@ -465,7 +465,7 @@ func (m *Metrics) RequestReported(
 }
 
 // LimitHit counts a request that broke a rate limit, a byte limit or the
-// error burst, by the window and the kind of hit.
+// refusal limit, by the window and the kind of hit.
 func (m *Metrics) LimitHit(hit ratelimit.Hit) {
 	m.rateLimitHits.WithLabelValues(hit.Window, hit.Kind).Inc()
 }