initialize metric mox_panic_total with 0, so the alerting rule also catches the first panic for a label

increase() and rate() don't seem to assume a previous value of 0 when a vector
gets a first value for a label. you would think that an increase() on a
first-value mox_panic_total{"..."}=1 would return 1, and similar for rate(), but
that doesn't appear to be the behaviour. so we just explicitly initialize the
count to 0 for each possible label value. mox has more vector metrics, but
panics feels like the most important, and it's too much code to initialize them
all, for all combinations of label values. there is probably a better way that
fixes this for all cases...

ctl.go

@@ -282,7 +282,7 @@ func servectl(ctx context.Context, log *mlog.Log, conn net.Conn, shutdown func()
 		}
 		log.Error("servectl panic", mlog.Field("err", x), mlog.Field("cmd", ctl.cmd))
 		debug.PrintStack()
-		metrics.PanicInc("ctl")
+		metrics.PanicInc(metrics.Ctl)
 	}()
 
 	defer conn.Close()

dkim/dkim.go

@@ -41,7 +41,7 @@ var (
 	metricDKIMSign = promauto.NewCounterVec(
 		prometheus.CounterOpts{
 			Name: "mox_dkim_sign_total",
-			Help: "DKIM messages signings.",
+			Help: "DKIM messages signings, label key is the type of key, rsa or ed25519.",
 		},
 		[]string{
 			"key",

imapserver/server.go

@@ -682,7 +682,7 @@ func serve(listenerName string, cid int64, tlsConfig *tls.Config, nc net.Conn, x
 		} else {
 			c.log.Error("unhandled panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("imapserver")
+			metrics.PanicInc(metrics.Imapserver)
 		}
 	}()
 

import.go

@@ -256,7 +256,7 @@ func importctl(ctx context.Context, ctl *ctl, mbox bool) {
 		if x != ctl.x {
 			ctl.log.Error("import error", mlog.Field("panic", fmt.Errorf("%v", x)))
 			debug.PrintStack()
-			metrics.PanicInc("import")
+			metrics.PanicInc(metrics.Import)
 		} else {
 			ctl.log.Error("import error")
 		}

metrics/panic.go

@@ -15,6 +15,59 @@ var metricPanic = promauto.NewCounterVec(
 	},
 )
 
-func PanicInc(pkg string) {
-	metricPanic.WithLabelValues(pkg).Inc()
+type Panic string
+
+const (
+	Ctl              Panic = "ctl"
+	Import           Panic = "import"
+	Serve            Panic = "serve"
+	Imapserver       Panic = "imapserver"
+	Mtastsdb         Panic = "mtastsdb"
+	Queue            Panic = "queue"
+	Smtpclient       Panic = "smtpclient"
+	Smtpserver       Panic = "smtpserver"
+	Dkimverify       Panic = "dkimverify"
+	Spfverify        Panic = "spfverify"
+	Upgradethreads   Panic = "upgradethreads"
+	Importmanage     Panic = "importmanage"
+	Importmessages   Panic = "importmessages"
+	Webadmin         Panic = "webadmin"
+	Webmailsendevent Panic = "webmailsendevent"
+	Webmail          Panic = "webmail"
+	Webmailrequest   Panic = "webmailrequest"
+	Webmailquery     Panic = "webmailquery"
+	Webmailhandle    Panic = "webmailhandle"
+)
+
+func init() {
+	// Ensure the panic counts are initialized to 0, so the query for change also picks
+	// up the first panic.
+	names := []Panic{
+		Ctl,
+		Import,
+		Serve,
+		Imapserver,
+		Mtastsdb,
+		Queue,
+		Smtpclient,
+		Smtpserver,
+		Dkimverify,
+		Spfverify,
+		Upgradethreads,
+		Importmanage,
+		Importmessages,
+		Webadmin,
+		Webmailsendevent,
+		Webmail,
+		Webmailrequest,
+		Webmailquery,
+		Webmailhandle,
+	}
+	for _, name := range names {
+		metricPanic.WithLabelValues(string(name)).Add(0)
+	}
+}
+
+func PanicInc(name Panic) {
+	metricPanic.WithLabelValues(string(name)).Inc()
 }

mtastsdb/refresh.go

@@ -112,7 +112,7 @@ func refreshDomain(ctx context.Context, db *bstore.DB, resolver dns.Resolver, pr
 			// Should not happen, but make sure errors don't take down the application.
 			log.Error("refresh1", mlog.Field("panic", x))
 			debug.PrintStack()
-			metrics.PanicInc("mtastsdb")
+			metrics.PanicInc(metrics.Mtastsdb)
 		}
 	}()
 

queue/queue.go

@@ -497,7 +497,7 @@ func deliver(resolver dns.Resolver, m Msg) {
 		if x != nil {
 			qlog.Error("deliver panic", mlog.Field("panic", x))
 			debug.PrintStack()
-			metrics.PanicInc("queue")
+			metrics.PanicInc(metrics.Queue)
 		}
 	}()
 

serve.go

@@ -44,7 +44,7 @@ func monitorDNSBL(log *mlog.Log) {
 		if x != nil {
 			log.Error("monitordnsbl panic", mlog.Field("panic", x))
 			debug.PrintStack()
-			metrics.PanicInc("serve")
+			metrics.PanicInc(metrics.Serve)
 		}
 	}()
 

smtpclient/client.go

@@ -457,7 +457,7 @@ func (c *Client) recover(rerr *error) {
 	}
 	cerr, ok := x.(Error)
 	if !ok {
-		metrics.PanicInc("smtpclient")
+		metrics.PanicInc(metrics.Smtpclient)
 		panic(x)
 	}
 	*rerr = cerr

smtpserver/server.go

@@ -595,7 +595,7 @@ func serve(listenerName string, cid int64, hostname dns.Domain, tlsConfig *tls.C
 		} else {
 			c.log.Error("unhandled panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("smtpserver")
+			metrics.PanicInc(metrics.Smtpserver)
 		}
 	}()
 
@@ -1903,7 +1903,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
 			if x != nil {
 				c.log.Error("dkim verify panic", mlog.Field("err", x))
 				debug.PrintStack()
-				metrics.PanicInc("dkimverify")
+				metrics.PanicInc(metrics.Dkimverify)
 			}
 		}()
 		defer wg.Done()
@@ -1939,7 +1939,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
 			if x != nil {
 				c.log.Error("spf verify panic", mlog.Field("err", x))
 				debug.PrintStack()
-				metrics.PanicInc("spfverify")
+				metrics.PanicInc(metrics.Spfverify)
 			}
 		}()
 		defer wg.Done()

store/account.go

@@ -855,7 +855,7 @@ func OpenAccountDB(accountDir, accountName string) (a *Account, rerr error) {
 			if x != nil {
 				xlog.Error("upgradeThreads panic", mlog.Field("err", x))
 				debug.PrintStack()
-				metrics.PanicInc("upgradeThreads")
+				metrics.PanicInc(metrics.Upgradethreads)
 				acc.threadsErr = fmt.Errorf("panic during upgradeThreads: %v", x)
 			}
 

webaccount/import.go

@@ -69,7 +69,7 @@ func ImportManage() {
 		if x := recover(); x != nil {
 			log.Error("import manage panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("importmanage")
+			metrics.PanicInc(metrics.Importmanage)
 		}
 	}()
 
@@ -342,7 +342,7 @@ func importMessages(ctx context.Context, log *mlog.Log, token string, acc *store
 		} else {
 			log.Error("import panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("importmessages")
+			metrics.PanicInc(metrics.Importmessages)
 		}
 	}()
 

webadmin/admin.go

@@ -367,7 +367,7 @@ func logPanic(ctx context.Context) {
 	log := xlog.WithContext(ctx)
 	log.Error("recover from panic", mlog.Field("panic", x))
 	debug.PrintStack()
-	metrics.PanicInc("webadmin")
+	metrics.PanicInc(metrics.Webadmin)
 }
 
 // return IPs we may be listening on.

webmail/eventwriter.go

@@ -84,7 +84,7 @@ func (ew *eventWriter) xsendEvent(ctx context.Context, log *mlog.Log, name strin
 				if x != nil {
 					log.WithContext(ctx).Error("writeEvent panic", mlog.Field("err", x))
 					debug.PrintStack()
-					metrics.PanicInc("webmail-sendEvent")
+					metrics.PanicInc(metrics.Webmailsendevent)
 				}
 			}()
 

webmail/view.go

@@ -568,7 +568,7 @@ func serveEvents(ctx context.Context, log *mlog.Log, w http.ResponseWriter, r *h
 		} else {
 			log.WithContext(ctx).Error("serveEvents panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("webmail")
+			metrics.PanicInc(metrics.Webmail)
 			panic(x)
 		}
 	}()
@@ -1216,7 +1216,7 @@ func viewRequestTx(ctx context.Context, log *mlog.Log, acc *store.Account, tx *b
 		if x != nil {
 			log.WithContext(ctx).Error("viewRequestTx panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("webmail-request")
+			metrics.PanicInc(metrics.Webmailrequest)
 		}
 	}()
 
@@ -1300,7 +1300,7 @@ func queryMessages(ctx context.Context, log *mlog.Log, acc *store.Account, tx *b
 			log.WithContext(ctx).Error("queryMessages panic", mlog.Field("err", x))
 			debug.PrintStack()
 			mrc <- msgResp{err: fmt.Errorf("query failed")}
-			metrics.PanicInc("webmail-query")
+			metrics.PanicInc(metrics.Webmailquery)
 		}
 
 		close(mrc)

webmail/webmail.go

@@ -381,7 +381,7 @@ func handle(apiHandler http.Handler, w http.ResponseWriter, r *http.Request) {
 		if !ok {
 			log.WithContext(ctx).Error("handle panic", mlog.Field("err", x))
 			debug.PrintStack()
-			metrics.PanicInc("webmail-handle")
+			metrics.PanicInc(metrics.Webmailhandle)
 			panic(x)
 		}
 		if strings.HasPrefix(err.Code, "user:") {