Setup a working pipeline

* add tests to ensure function even after switching docker client api version
* switch docker client api version to remove import of Sirupsen and get rid of the casing workaround
* migrate from glide to dep to go modules
* rewrite ci workflow
  * only run publish on version tags
  * only run build on branches
  * update goreleaser config
  * disable automated latest tag push
* remove dependency to v2tec/docker-gobuilder
* remove dead code and files
* add golands .idea folder to gitignore
* add label to released docker images
* add test reporting, add some unit tests
* change test output dir
* fix goreleaser versions
* add debug output for circleci and goreleaser
* disable cgo

container/container.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
-
+	log "github.com/sirupsen/logrus"
 	"github.com/docker/docker/api/types"
 	dockercontainer "github.com/docker/docker/api/types/container"
 )
@@ -102,8 +102,9 @@ func (c Container) Links() []string {
 // identified by the presence of the "com.centurylinklabs.watchtower" label in
 // the container metadata.
 func (c Container) IsWatchtower() bool {
-	val, ok := c.containerInfo.Config.Labels[watchtowerLabel]
-	return ok && val == "true"
+	log.Debugf("Checking if %s is a watchtower instance.", c.Name())
+	wasWatchtower := ContainsWatchtowerLabel(c.containerInfo.Config.Labels)
+	return wasWatchtower
 }
 
 // StopSignal returns the custom stop signal (if any) that is encoded in the
@@ -182,3 +183,10 @@ func (c Container) hostConfig() *dockercontainer.HostConfig {
 
 	return hostConfig
 }
+
+// ContainsWatchtowerLabel takes a map of labels and values and tells
+// the consumer whether it contains a valid watchtower instance label
+func ContainsWatchtowerLabel(labels map[string]string) bool {
+	val, ok := labels[watchtowerLabel]
+	return ok && val == "true"
+}