Merge pull request #3532 from justinsb/warn_if_no_docker_version

Automatic merge from submit-queue.

nodeup: warn if no docker version matched

nodeup/pkg/model/docker.go

@@ -472,12 +472,15 @@ func (b *DockerBuilder) Build(c *fi.ModelBuilderContext) error {
 
 	// Add packages
 	{
+		count := 0
 		for i := range dockerVersions {
 			dv := &dockerVersions[i]
 			if !dv.matches(b.Architecture, dockerVersion, b.Distribution) {
 				continue
 			}
 
+			count++
+
 			c.AddTask(&nodetasks.Package{
 				Name:    dv.Name,
 				Version: s(dv.Version),
@@ -494,6 +497,10 @@ func (b *DockerBuilder) Build(c *fi.ModelBuilderContext) error {
 
 			// Note we do _not_ stop looping... centos/rhel comprises multiple packages
 		}
+
+		if count == 0 {
+			glog.Warningf("Did not find docker package for %s %s %s", b.Distribution, b.Architecture, dockerVersion)
+		}
 	}
 
 	dockerSemver, err := semver.ParseTolerant(dockerVersion)