Add utf8-strict-mode flag for mimirtool (#7227)

* Add utf8-strict-mode flag for mimirtool

This commit adds a new flag to mimirtool called utf8-strict-mode.
It is the client version the utf8-strict-mode-enabled flag in Mimir.

The default mode of mimirtool is to first use the new parser for
UTF-8 matchers, and if it fails, fallback to the classic parser.
If this happens, it also logs a warning to stdout.

It is possible to disable the fallback, and use just the UTF-8 parser,
with the -utf8-strict-mode flag. This will help operators ensure their
configurations are compatible with the new parser going forward.

pkg/mimirtool/commands/alerts.go

@@ -19,9 +19,13 @@ import (
 	"time"
 
 	"github.com/alecthomas/kingpin/v2"
+	gokitlog "github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/grafana/dskit/cancellation"
 	"github.com/pkg/errors"
 	"github.com/prometheus/alertmanager/config"
+	"github.com/prometheus/alertmanager/featurecontrol"
+	"github.com/prometheus/alertmanager/matchers/compat"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -41,6 +45,7 @@ type AlertmanagerCommand struct {
 	DisableColor           bool
 	ValidateOnly           bool
 	OutputDir              string
+	UTF8StrictMode         bool
 
 	cli *client.MimirClient
 }
@@ -71,6 +76,8 @@ func (a *AlertmanagerCommand) Register(app *kingpin.Application, envVars EnvVarN
 	alertCmd.Flag("tls-key-path", "TLS client certificate private key to authenticate with the Grafana Mimir API as part of mTLS; alternatively, set "+envVars.TLSKeyPath+".").Default("").Envar(envVars.TLSKeyPath).StringVar(&a.ClientConfig.TLS.KeyPath)
 	alertCmd.Flag("tls-insecure-skip-verify", "Skip TLS certificate verification; alternatively, set "+envVars.TLSInsecureSkipVerify+".").Default("false").Envar(envVars.TLSInsecureSkipVerify).BoolVar(&a.ClientConfig.TLS.InsecureSkipVerify)
 	alertCmd.Flag("auth-token", "Authentication token bearer authentication; alternatively, set "+envVars.AuthToken+".").Default("").Envar(envVars.AuthToken).StringVar(&a.ClientConfig.AuthToken)
+	alertCmd.Flag("utf8-strict-mode", "Enable UTF-8 strict mode. Allows UTF-8 characters in the matchers for routes and inhibition rules, in silences, and in the labels for alerts.").Default("false").BoolVar(&a.UTF8StrictMode)
+
 	// Get Alertmanager Configs Command
 	getAlertsCmd := alertCmd.Command("get", "Get the Alertmanager configuration that is currently in the Grafana Mimir Alertmanager.").Action(a.getConfig)
 	getAlertsCmd.Flag("disable-color", "disable colored output").BoolVar(&a.DisableColor)
@@ -93,6 +100,22 @@ func (a *AlertmanagerCommand) Register(app *kingpin.Application, envVars EnvVarN
 }
 
 func (a *AlertmanagerCommand) setup(_ *kingpin.ParseContext) error {
+	// The default mode for mimirtool is to first use the new parser for UTF-8 matchers,
+	// and if it fails, fallback to the classic parser. If this happens, it also logs a
+	// warning to stdout. It is possible to disable to fallback, and use just the UTF-8
+	// parser, with the -utf8-strict-mode flag. This will help operators ensure their
+	// configurations are compatible with the new parser going forward.
+	l := level.NewFilter(gokitlog.NewLogfmtLogger(os.Stdout), level.AllowInfo())
+	features := ""
+	if a.UTF8StrictMode {
+		features = featurecontrol.FeatureUTF8StrictMode
+	}
+	flags, err := featurecontrol.NewFlags(l, features)
+	if err != nil {
+		return err
+	}
+	compat.InitFromFlags(l, compat.RegisteredMetrics, flags)
+
 	cli, err := client.New(a.ClientConfig)
 	if err != nil {
 		return err