expose vtbackup stats at --port /metrics (#11388)

* expose /metrics from vtbackup http --port

Signed-off-by: Max Englander <max@planetscale.com>

* -mathrand seed

Signed-off-by: Max Englander <max@planetscale.com>

Signed-off-by: Max Englander <max@planetscale.com>

go/cmd/vtbackup/plugin_prometheusbackend.go

@@ -0,0 +1,31 @@
+/*
+Copyright 2022 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+// This plugin imports Prometheus to allow for instrumentation
+// with the Prometheus client library
+
+import (
+	"vitess.io/vitess/go/stats/prometheusbackend"
+	"vitess.io/vitess/go/vt/servenv"
+)
+
+func init() {
+	servenv.OnRun(func() {
+		prometheusbackend.Init("vtbackup")
+	})
+}

go/cmd/vtbackup/vtbackup.go

@@ -64,7 +64,6 @@ import (
 	"math"
 	"math/big"
 	"os"
-	"os/signal"
 	"strings"
 	"syscall"
 	"time"
@@ -113,11 +112,12 @@ var (
 	initShard          string
 	concurrency        = 4
 	// mysqlctld-like flags
-	mysqlPort     = 3306
-	mysqlSocket   string
-	mysqlTimeout  = 5 * time.Minute
-	initDBSQLFile string
-	detachedMode  bool
+	mysqlPort        = 3306
+	mysqlSocket      string
+	mysqlTimeout     = 5 * time.Minute
+	initDBSQLFile    string
+	detachedMode     bool
+	keepAliveTimeout = 0 * time.Second
 )
 
 func registerFlags(fs *pflag.FlagSet) {
@@ -138,19 +138,36 @@ func registerFlags(fs *pflag.FlagSet) {
 	fs.DurationVar(&mysqlTimeout, "mysql_timeout", mysqlTimeout, "how long to wait for mysqld startup")
 	fs.StringVar(&initDBSQLFile, "init_db_sql_file", initDBSQLFile, "path to .sql file to run after mysql_install_db")
 	fs.BoolVar(&detachedMode, "detach", detachedMode, "detached mode - run backups detached from the terminal")
+	fs.DurationVar(&keepAliveTimeout, "keep-alive-timeout", keepAliveTimeout, "Wait until timeout elapses after a successful backup before shutting down.")
 
 	acl.RegisterFlags(fs)
 }
 
 func init() {
+	servenv.RegisterDefaultFlags()
+	dbconfigs.RegisterFlags(dbconfigs.All...)
+	mysqlctl.RegisterFlags()
 	servenv.OnParse(registerFlags)
 }
 
 func main() {
 	defer exit.Recover()
-	dbconfigs.RegisterFlags(dbconfigs.All...)
-	mysqlctl.RegisterFlags()
+
 	servenv.ParseFlags("vtbackup")
+	servenv.Init()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	servenv.OnClose(func() {
+		cancel()
+	})
+
+	defer func() {
+		servenv.ExitChan <- syscall.SIGTERM
+		<-ctx.Done()
+	}()
+
+	go servenv.RunDefault()
+
 	if detachedMode {
 		// this method will call os.Exit and kill this process
 		cmd.DetachFromTerminalAndExit()
@@ -163,16 +180,6 @@ func main() {
 		exit.Return(1)
 	}
 
-	// Catch SIGTERM and SIGINT so we get a chance to clean up.
-	ctx, cancel := context.WithCancel(context.Background())
-	sigChan := make(chan os.Signal, 1)
-	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
-	go func() {
-		sig := <-sigChan
-		log.Infof("Cancelling due to signal: %v", sig)
-		cancel()
-	}()
-
 	// Open connection backup storage.
 	backupStorage, err := backupstorage.GetBackupStorage()
 	if err != nil {
@@ -205,6 +212,15 @@ func main() {
 		log.Errorf("Couldn't prune old backups: %v", err)
 		exit.Return(1)
 	}
+
+	if keepAliveTimeout > 0 {
+		log.Infof("Backup was successful, waiting %s before exiting (or until context expires).", keepAliveTimeout)
+		select {
+		case <-time.After(keepAliveTimeout):
+		case <-ctx.Done():
+		}
+	}
+	log.Info("Exiting.")
 }
 
 func takeBackup(ctx context.Context, topoServer *topo.Server, backupStorage backupstorage.BackupStorage) error {

go/flags/endtoend/vtbackup.txt

@@ -81,6 +81,7 @@ Usage of vtbackup:
       --init_keyspace string                            (init parameter) keyspace to use for this tablet
       --init_shard string                               (init parameter) shard to use for this tablet
       --initial_backup                                  Instead of restoring from backup, initialize an empty database with the provided init_db_sql_file and upload a backup of that for the shard, if the shard has no backups yet. This can be used to seed a brand new shard with an initial, empty backup. If any backups already exist for the shard, this will be considered a successful no-op. This can only be done before the shard exists in topology (i.e. before any tablets are deployed).
+      --keep-alive-timeout duration                     Wait until timeout elapses after a successful backup before shutting down.
       --keep_logs duration                              keep logs for this long (using ctime) (zero to keep forever)
       --keep_logs_by_mtime duration                     keep logs for this long (using mtime) (zero to keep forever)
       --log_backtrace_at traceLocation                  when logging hits line file:N, emit a stack trace (default :0)
@@ -113,6 +114,7 @@ Usage of vtbackup:
       --mysql_server_version string                     MySQL server version to advertise.
       --mysql_socket string                             path to the mysql socket
       --mysql_timeout duration                          how long to wait for mysqld startup (default 5m0s)
+      --port int                                        port for the server
       --pprof strings                                   enable profiling
       --purge_logs_interval duration                    how often try to remove old logs (default 1h0m0s)
       --remote_operation_timeout duration               time to wait for a remote operation (default 30s)