Read every setting through viper and rename the settings (closes #211)

Every setting of discriminator and rproxy is read through viper, in place
of the os.LookupEnv function Main passed down. NewViper turns AutomaticEnv
and AllowEmptyEnv on, so a setting that is set but empty reads as set. A
setting may also be given as a file, the _FILE form, which rproxy's
settings now have too; rproxy still writes nothing to disk.

The settings are renamed. Discriminator's take the prefix SWW_WAF_,
rproxy's take SWW_RPROXY_, and the shared SWW_COMMAND keeps SWW_. The Core
Rule Set's settings take SWW_WAF_CORE_RULE_SET_ rather than SWW_WAF_WAF_.
Every place a name appeared changed: the code, the viper keys, tests,
documents, examples, the README's settings table and the image files.

Model: deepseek-v4-pro

internal/discriminator/proxy.go

@@ -33,15 +33,15 @@ const adminPrefix = "/_sww/"
 const HealthPath = "/_sww/healthz"
 
 // MetricsPath is where the metrics are, for a request that carries
-// SWW_METRICS_TOKEN.
+// SWW_WAF_METRICS_TOKEN.
 const MetricsPath = "/_sww/metrics"
 
 // BansPath is where an admin lists and adds bans, and, followed by / and
-// a client's address, lifts them, with SWW_ADMIN_TOKEN.
+// a client's address, lifts them, with SWW_WAF_ADMIN_TOKEN.
 const BansPath = "/_sww/bans"
 
 // ClientsPath is where an admin asks what discriminator knows of a client, by
-// the client's address after it, with SWW_ADMIN_TOKEN.
+// the client's address after it, with SWW_WAF_ADMIN_TOKEN.
 const ClientsPath = "/_sww/clients/"
 
 // Params are what New needs.
@@ -54,16 +54,16 @@ type Params struct {
 	// ProcessLog receives the process's own messages.
 	ProcessLog *slog.Logger
 	// GeoJSURL is where clients' AS numbers and countries are looked up
-	// while SWW_LOOKUP_SOURCE is geojs, normally lookup.URL.
+	// while SWW_WAF_LOOKUP_SOURCE is geojs, normally lookup.URL.
 	GeoJSURL string
 	// AbuseIPDBURL is where clients are checked with AbuseIPDB while
-	// SWW_ABUSEIPDB_KEY is set, normally reputation.AbuseIPDBURL.
+	// SWW_WAF_ABUSEIPDB_KEY is set, normally reputation.AbuseIPDBURL.
 	AbuseIPDBURL string
 	// LookupFile is the lookup database they are looked up in while
-	// SWW_LOOKUP_SOURCE is file, and nil otherwise.
+	// SWW_WAF_LOOKUP_SOURCE is file, and nil otherwise.
 	LookupFile *lookup.File
 	// CoreRuleSet is what NewCoreRuleSet returns: what inspects requests
-	// while SWW_WAF_MODE is not off, and nil while it is.
+	// while SWW_WAF_CORE_RULE_SET_MODE is not off, and nil while it is.
 	CoreRuleSet *waf.CoreRuleSet
 	// Now tells the time by which requests are counted for the rate
 	// limits, bans are made and run out, and GeoJS's answers are kept,
@@ -76,14 +76,14 @@ type Params struct {
 	// permanent, for each count over an anomaly threshold, for each request
 	// whose client a blocklist, the CrowdSec decision list, a DNSBL zone or
 	// AbuseIPDB lists, for each request the Core Rule Set scores at or over
-	// SWW_WAF_ANOMALY_THRESHOLD, and for GeoJS failing, a fetch of a list
+	// SWW_WAF_CORE_RULE_SET_ANOMALY_THRESHOLD, and for GeoJS failing, a fetch of a list
 	// failing, a query to a DNSBL zone or a check with AbuseIPDB failing,
 	// or the day's AbuseIPDB checks used up.
 	Alerts *alerts.Queue
 }
 
 // Server is the server discriminator runs, with the parts whose state the state
-// files keep, the lookup database, nil unless SWW_LOOKUP_SOURCE is file, the
+// files keep, the lookup database, nil unless SWW_WAF_LOOKUP_SOURCE is file, the
 // lists fetched from URLs, which its Run fetches, the DNSBL zones' verdicts,
 // AbuseIPDB's scores and checks spent, and the metrics.
 type Server struct {
@@ -175,7 +175,7 @@ func newHandler(params Params) *handler {
 // newReputation returns the lists fetched from URLs, the DNSBL zones'
 // verdicts and AbuseIPDB's scores, as the settings in params name them,
 // with none fetched, asked for or checked yet, and adds their metrics to
-// m, AbuseIPDB's while SWW_ABUSEIPDB_KEY is set.
+// m, AbuseIPDB's while SWW_WAF_ABUSEIPDB_KEY is set.
 func newReputation(
 	params Params, m *metrics.Metrics,
 ) (*reputation.Lists, *reputation.DNSBL, *reputation.AbuseIPDB) {
@@ -207,11 +207,11 @@ func newReputation(
 	return lists, dnsbl, abuseIPDB
 }
 
-// NewCoreRuleSet returns the Core Rule Set at SWW_WAF_PARANOIA_LEVEL,
-// without the rules SWW_WAF_DISABLED_RULES switches off, reading bodies
-// up to SWW_WAF_BODY_LIMIT, with the exclusions in
-// SWW_CORE_RULE_SET_EXCLUSIONS_FILE, or nil while SWW_WAF_MODE is off. It
-// reads at most QuestionBodyMaxBytes less one byte: a question's body of
+// NewCoreRuleSet returns the Core Rule Set at SWW_WAF_CORE_RULE_SET_PARANOIA_LEVEL,
+// without the rules SWW_WAF_CORE_RULE_SET_DISABLED_RULES switches off, reading bodies
+// up to SWW_WAF_CORE_RULE_SET_BODY_LIMIT, with the exclusions in
+// SWW_WAF_CORE_RULE_SET_EXCLUSIONS_FILE, or nil while SWW_WAF_CORE_RULE_SET_MODE is
+// off. It reads at most QuestionBodyMaxBytes less one byte: a question's body of
 // QuestionBodyMaxBytes may be cut short, and the Core Rule Set does not read a
 // JSON or XML body over its limit. An exclusions file that waf.New refuses is
 // an error in every mode. While the mode is off, a set file is loaded with the
@@ -227,7 +227,7 @@ func NewCoreRuleSet(cfg *config.Config) (*waf.CoreRuleSet, error) {
 		ExclusionsFile: cfg.CoreRuleSetExclusionsFile,
 	})
 	if err != nil {
-		return nil, fmt.Errorf("SWW_CORE_RULE_SET_EXCLUSIONS_FILE: %w", err)
+		return nil, fmt.Errorf("SWW_WAF_CORE_RULE_SET_EXCLUSIONS_FILE: %w", err)
 	}
 
 	if cfg.WAFMode == config.WAFModeOff {