BUG/MEDIUM: fix haproxy version with multiple runtime clients

As haproxy version was a field of the client struct and the version set in a sync.Once function, the version was nil for all runtime clients except the first one. It could also happend that the first call was done with DoNotCheckRuntimeOnInit option and then, it could also happen that even the first one was nil.

.gitignore

@@ -2,3 +2,4 @@
 .idea/
 bin/golangci-lint
 bin/swagger
+.envrc

go.mod

@@ -18,6 +18,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/sirkon/dst v0.26.4
 	github.com/stretchr/testify v1.9.0
+	golang.org/x/sync v0.8.0
 	golang.org/x/text v0.19.0
 	golang.org/x/tools v0.26.0
 	gopkg.in/yaml.v3 v3.0.1
@@ -39,6 +40,5 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.mongodb.org/mongo-driver v1.17.1 // indirect
 	golang.org/x/mod v0.21.0 // indirect
-	golang.org/x/sync v0.8.0 // indirect
 	golang.org/x/sys v0.26.0 // indirect
 )

runtime/runtime_client.go

@@ -23,19 +23,18 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"sync"
 
 	native_errors "github.com/haproxytech/client-native/v6/errors"
 	"github.com/haproxytech/client-native/v6/misc"
 	"github.com/haproxytech/client-native/v6/models"
 	"github.com/haproxytech/client-native/v6/runtime/options"
+	"golang.org/x/sync/singleflight"
 )
 
 // Client handles multiple HAProxy clients
 type client struct {
-	haproxyVersion *HAProxyVersion
-	options        options.RuntimeOptions
-	runtime        *SingleRuntime
+	options options.RuntimeOptions
+	runtime *SingleRuntime
 }
 
 const (
@@ -90,50 +89,59 @@ func (c *client) GetInfo() (models.ProcessInfo, error) {
 	return result, nil
 }
 
-var versionSync sync.Once //nolint:gochecknoglobals
+var (
+	haproxyVersion *HAProxyVersion        //nolint:gochecknoglobals
+	versionKey     = "version"            //nolint:gochecknoglobals
+	versionSfg     = singleflight.Group{} //nolint:gochecknoglobals
+)
 
 // GetVersion returns info from the socket
 func (c *client) GetVersion() (HAProxyVersion, error) {
 	var err error
-	versionSync.Do(func() {
+	if haproxyVersion != nil {
+		return *haproxyVersion, nil
+	}
+	_, err, _ = versionSfg.Do(versionKey, func() (interface{}, error) {
 		version := &HAProxyVersion{}
 		var response string
 		response, err = c.runtime.ExecuteRaw("show info")
 		if err != nil {
-			return
+			return HAProxyVersion{}, err
 		}
 		for _, line := range strings.Split(response, "\n") {
 			if strings.HasPrefix(line, "Version: ") {
 				err = version.ParseHAProxyVersion(strings.TrimPrefix(line, "Version: "))
 				if err != nil {
-					return
+					return HAProxyVersion{}, err
 				}
-				c.haproxyVersion = version
-				return
+				haproxyVersion = version
+				return HAProxyVersion{}, err
 			}
 			// Starting with HAProxy 3.0, there is no more "Version:" prefix.
 			if len(line) > 0 && line[0] >= '3' && line[0] <= '9' {
 				err = version.ParseHAProxyVersion(line)
 				if err == nil {
-					c.haproxyVersion = version
+					haproxyVersion = version
 				}
-				return
+				return HAProxyVersion{}, err
 			}
 		}
 		err = errors.New("version data not found")
+		return HAProxyVersion{}, err // it's dereferenced in IsVersionBiggerOrEqual
 	})
 	if err != nil {
 		return HAProxyVersion{}, err
 	}
 
-	if c.haproxyVersion == nil {
+	if haproxyVersion == nil {
 		return HAProxyVersion{}, errors.New("version data not found")
 	}
-	return *c.haproxyVersion, err
+
+	return *haproxyVersion, err
 }
 
 func (c *client) IsVersionBiggerOrEqual(minimumVersion *HAProxyVersion) bool {
-	return IsBiggerOrEqual(minimumVersion, c.haproxyVersion)
+	return IsBiggerOrEqual(minimumVersion, haproxyVersion)
 }
 
 // Reloads HAProxy's configuration file. Similar to SIGUSR2. Returns the startup logs.
@@ -144,7 +152,7 @@ func (c *client) Reload() (string, error) {
 		return "", errors.New("cannot reload: not connected to a master socket")
 	}
 	if !c.IsVersionBiggerOrEqual(&HAProxyVersion{Major: 2, Minor: 7}) {
-		return "", errors.New("cannot reload: requires HAProxy 2.7 or later")
+		return "", fmt.Errorf("cannot reload: requires HAProxy 2.7 or later but current version is %v", haproxyVersion)
 	}
 
 	output, err := c.runtime.ExecuteMaster("reload")
@@ -218,7 +226,7 @@ func (c *client) AddServer(backend, name, attributes string) error {
 		return errors.New("no valid runtime found")
 	}
 	if !c.IsVersionBiggerOrEqual(&HAProxyVersion{Major: 2, Minor: 6}) {
-		return errors.New("this operation requires HAProxy 2.6 or later")
+		return fmt.Errorf("this operation requires HAProxy 2.6 or later but current version is %v", haproxyVersion)
 	}
 	err := c.runtime.AddServer(backend, name, attributes)
 	if err != nil {