remove: references to db collector

Remove final references to the deprecated database metric collector.
Remove counter for db connection errors.

BREAKING CHANGE: Remove `-db` CLI flag.

src/cfg/cfg.go

@@ -29,9 +29,6 @@ func Parse() *AppSettings {
 	flag.BoolVar(&appSettings.FileCollectorEnabled, "collector.textfile", false, "enable the textfile collector")
 	flag.StringVar(&appSettings.FileCollectorPath, "collector.textfile.directory", "", "directory to read text files with metrics from")
 
-	// deprecated: to be removed in next version
-	_ = flag.String("db", "", "path to the fail2ban sqlite database (removed)")
-
 	flag.Parse()
 	appSettings.validateFlags()
 	return appSettings

src/collector/f2b/collector.go

@@ -11,7 +11,6 @@ type Collector struct {
 	socketPath                 string
 	exporterVersion            string
 	lastError                  error
-	dbErrorCount               int
 	socketConnectionErrorCount int
 	socketRequestErrorCount    int
 }
@@ -21,7 +20,6 @@ func NewExporter(appSettings *cfg.AppSettings, exporterVersion string) *Collecto
 		socketPath:                 appSettings.Fail2BanSocketPath,
 		exporterVersion:            exporterVersion,
 		lastError:                  nil,
-		dbErrorCount:               0,
 		socketConnectionErrorCount: 0,
 		socketRequestErrorCount:    0,
 	}

src/collector/f2b/socket.go

@@ -69,9 +69,6 @@ var (
 )
 
 func (c *Collector) collectErrorCountMetric(ch chan<- prometheus.Metric) {
-	ch <- prometheus.MustNewConstMetric(
-		metricErrorCount, prometheus.CounterValue, float64(c.dbErrorCount), "db",
-	)
 	ch <- prometheus.MustNewConstMetric(
 		metricErrorCount, prometheus.CounterValue, float64(c.socketConnectionErrorCount), "socket_conn",
 	)