build: add pull flag to force image pulling

Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com>
Upstream-commit: 054e57a622e6a065c343806e7334920d17a03c5b
Component: engine

components/engine/builder/dispatchers.go

@@ -115,6 +115,12 @@ func from(b *Builder, args []string, attributes map[string]bool, original string
 	name := args[0]
 
 	image, err := b.Daemon.Repositories().LookupImage(name)
+	if b.Pull {
+		image, err = b.pullImage(name)
+		if err != nil {
+			return err
+		}
+	}
 	if err != nil {
 		if b.Daemon.Graph().IsNotExist(err) {
 			image, err = b.pullImage(name)

components/engine/builder/evaluator.go

@@ -90,6 +90,7 @@ type Builder struct {
 	// controls how images and containers are handled between steps.
 	Remove      bool
 	ForceRemove bool
+	Pull        bool
 
 	AuthConfig     *registry.AuthConfig
 	AuthConfigFile *registry.ConfigFile

components/engine/builder/job.go

@@ -35,6 +35,7 @@ func (b *BuilderJob) CmdBuild(job *engine.Job) engine.Status {
 		noCache        = job.GetenvBool("nocache")
 		rm             = job.GetenvBool("rm")
 		forceRm        = job.GetenvBool("forcerm")
+		pull           = job.GetenvBool("pull")
 		authConfig     = &registry.AuthConfig{}
 		configFile     = &registry.ConfigFile{}
 		tag            string
@@ -111,6 +112,7 @@ func (b *BuilderJob) CmdBuild(job *engine.Job) engine.Status {
 		UtilizeCache:    !noCache,
 		Remove:          rm,
 		ForceRemove:     forceRm,
+		Pull:            pull,
 		OutOld:          job.Stdout,
 		StreamFormatter: sf,
 		AuthConfig:      authConfig,