From ef09ca898794c9d7cd2bf6ecc518d3abf972f5c4 Mon Sep 17 00:00:00 2001
From: Anda Xu <anda.xu@docker.com>
Date: Mon, 6 Aug 2018 14:16:11 -0700
Subject: [PATCH] enable buildkit as builder from daemon; no env var needs to
 be set

Signed-off-by: Anda Xu <anda.xu@docker.com>
---
 cli/command/cli.go         |  2 ++
 cli/command/image/build.go | 11 ++---------
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/cli/command/cli.go b/cli/command/cli.go
index 25aaf64b5c..9d169e6727 100644
--- a/cli/command/cli.go
+++ b/cli/command/cli.go
@@ -208,6 +208,7 @@ func (cli *DockerCli) initializeFromClient() {
 	cli.serverInfo = ServerInfo{
 		HasExperimental: ping.Experimental,
 		OSType:          ping.OSType,
+		BuildkitEnabled: ping.Buildkit,
 	}
 	cli.client.NegotiateAPIVersionPing(ping)
 }
@@ -241,6 +242,7 @@ func (cli *DockerCli) NewContainerizedEngineClient(sockPath string) (containeriz
 type ServerInfo struct {
 	HasExperimental bool
 	OSType          string
+	BuildkitEnabled bool
 }
 
 // ClientInfo stores details about the supported features of the client
diff --git a/cli/command/image/build.go b/cli/command/image/build.go
index df67a7731f..8105341bfd 100644
--- a/cli/command/image/build.go
+++ b/cli/command/image/build.go
@@ -13,7 +13,6 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
-	"strconv"
 	"strings"
 
 	"github.com/docker/cli/cli"
@@ -181,14 +180,8 @@ func (out *lastProgressOutput) WriteProgress(prog progress.Progress) error {
 
 // nolint: gocyclo
 func runBuild(dockerCli command.Cli, options buildOptions) error {
-	if buildkitEnv := os.Getenv("DOCKER_BUILDKIT"); buildkitEnv != "" {
-		enableBuildkit, err := strconv.ParseBool(buildkitEnv)
-		if err != nil {
-			return errors.Wrap(err, "DOCKER_BUILDKIT environment variable expects boolean value")
-		}
-		if enableBuildkit {
-			return runBuildBuildKit(dockerCli, options)
-		}
+	if dockerCli.ServerInfo().BuildkitEnabled && dockerCli.ServerInfo().HasExperimental {
+		return runBuildBuildKit(dockerCli, options)
 	}
 
 	var (