Validate tags

builder/digitalocean/config.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"regexp"
 	"time"
 
 	"github.com/hashicorp/packer/common"
@@ -125,6 +126,13 @@ func NewConfig(raws ...interface{}) (*Config, []string, error) {
 	if c.Tags == nil {
 		c.Tags = make([]string, 0)
 	}
+	tagRe := regexp.MustCompile("^[[:alnum:]:_-]{1,255}$")
+
+	for _, t := range c.Tags {
+		if !tagRe.MatchString(t) {
+			errs = packer.MultiErrorAppend(errs, errors.New(fmt.Sprintf("invalid tag: %s", t)))
+		}
+	}
 
 	if errs != nil && len(errs.Errors) > 0 {
 		return nil, nil, errs