add build_args_from_env parameter

docker.go

@@ -43,6 +43,7 @@ type (
 		Context     string   // Docker build context
 		Tags        []string // Docker build tags
 		Args        []string // Docker build args
+		ArgsEnv     []string // Docker build args from env
 		Squash      bool     // Docker build squash
 		Pull        bool     // Docker build pull
 		Compress    bool     // Docker build compress
@@ -194,6 +195,9 @@ func commandBuild(build Build) *exec.Cmd {
 	if build.Pull {
 		args = append(args, "--pull=true")
 	}
+	for _, arg := range build.ArgsEnv {
+		addProxyValue(&build, arg)
+	}
 	for _, arg := range build.Args {
 		args = append(args, "--build-arg", arg)
 	}