Feature: show Alpine version at start

cmd/gluetun/main.go

@@ -144,6 +144,7 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 	fmt.Println(gluetunLogging.Splash(buildInfo))
 
 	printVersions(ctx, logger, map[string]func(ctx context.Context) (string, error){
+		"Alpine":   alpineConf.Version,
 		"OpenVPN":  ovpnConf.Version,
 		"Unbound":  dnsConf.Version,
 		"IPtables": firewallConf.Version,

internal/alpine/alpine.go

@@ -2,12 +2,15 @@
 package alpine
 
 import (
+	"context"
+
 	"github.com/qdm12/golibs/os"
 	"github.com/qdm12/golibs/os/user"
 )
 
 type Configurator interface {
 	CreateUser(username string, uid int) (createdUsername string, err error)
+	Version(ctx context.Context) (version string, err error)
 }
 
 type configurator struct {

internal/alpine/version.go

@@ -0,0 +1,27 @@
+package alpine
+
+import (
+	"context"
+	"io"
+	"os"
+	"strings"
+)
+
+func (c *configurator) Version(ctx context.Context) (version string, err error) {
+	file, err := c.openFile("/etc/alpine-release", os.O_RDONLY, 0)
+	if err != nil {
+		return "", err
+	}
+
+	b, err := io.ReadAll(file)
+	if err != nil {
+		return "", err
+	}
+
+	if err := file.Close(); err != nil {
+		return "", err
+	}
+
+	version = strings.ReplaceAll(string(b), "\n", "")
+	return version, nil
+}