eskip: remove flowid dependency (#3065)

eskip package is generally useful without proxy or filters and therefore
ideally should have minimal number of dependencies.

This change deprecates GenerateIfNeeded which is only used by etcd dataclient and
reimplements it to remove dependency on github.com/zalando/skipper/filters/flowid

See 35ba6cc

Signed-off-by: Alexander Yastrebov <[email protected]>

Author: AlexanderYastrebov

eskip/eskip.go

@@ -5,13 +5,13 @@ package eskip
 import (
 	"errors"
 	"fmt"
+	"math/rand"
 	"net/url"
 	"regexp"
 	"strings"
 	"sync"
 
 	log "github.com/sirupsen/logrus"
-	"github.com/zalando/skipper/filters/flowid"
 )
 
 const duplicateHeaderPredicateErrorFmt = "duplicate header predicate: %s"
@@ -712,29 +712,28 @@ func ParsePredicates(p string) ([]*Predicate, error) {
 	return ps, nil
 }
 
-const randomIdLength = 16
-
-var routeIdRx = regexp.MustCompile(`\W`)
+const (
+	randomIdLength = 16
+	// does not contain underscore to produce compatible output with previously used flow id generator
+	alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+)
 
 // generate weak random id for a route if
 // it doesn't have one.
+//
+// Deprecated: do not use, generate valid route id that matches [a-zA-Z_] yourself.
 func GenerateIfNeeded(existingId string) string {
 	if existingId != "" {
 		return existingId
 	}
 
-	// using this to avoid adding a new dependency.
-	g, err := flowid.NewStandardGenerator(randomIdLength)
-	if err != nil {
-		return existingId
-	}
-	id, err := g.Generate()
-	if err != nil {
-		return existingId
+	var sb strings.Builder
+	sb.WriteString("route")
+
+	for i := 0; i < randomIdLength; i++ {
+		ai := rand.Intn(len(alphabet))
+		sb.WriteByte(alphabet[ai])
 	}
 
-	// replace characters that are not allowed
-	// for eskip route ids.
-	id = routeIdRx.ReplaceAllString(id, "x")
-	return "route" + id
+	return sb.String()
 }

etcd/etcd.go

@@ -493,6 +493,7 @@ func (c *Client) Delete(id string) error {
 
 func (c *Client) UpsertAll(routes []*eskip.Route) error {
 	for _, r := range routes {
+		//lint:ignore SA1019 due to backward compatibility
 		r.Id = eskip.GenerateIfNeeded(r.Id)
 		err := c.Upsert(r)
 		if err != nil {