Initial support for tagging with git desribe output

**What**
- Adds new GetGitDescribe ouput command, use this command in the build,
deploy, generate, and push commands.

Signed-off-by: Lucas Roesler <roesler.lucas@gmail.com>

schema/image.go

@@ -9,23 +9,32 @@ type BuildFormat int
 // DefaultFormat as defined in the YAML file or appending :latest
 const DefaultFormat BuildFormat = 0
 
+// SHAFormat uses "latest-<sha>" as the docker tag
 const SHAFormat BuildFormat = 1
 
+// BranchAndSHAFormat uses "latest-<branch>-<sha>" as the docker tag
 const BranchAndSHAFormat BuildFormat = 2
 
+// DescribeFormat uses the git-describe output as the docker tag
+const DescribeFormat BuildFormat = 3
+
 // BuildImageName builds a Docker image tag for build, push or deploy
-func BuildImageName(format BuildFormat, image string, SHA string, branch string) string {
+func BuildImageName(format BuildFormat, image string, version string, branch string) string {
 	imageVal := image
 	if strings.Contains(image, ":") == false {
 		imageVal += ":latest"
 	}
 
-	if format == SHAFormat {
-		return imageVal + "-" + SHA
+	switch format {
+	case SHAFormat:
+		return imageVal + "-" + version
+	case BranchAndSHAFormat:
+		return imageVal + "-" + branch + "-" + version
+	case DescribeFormat:
+		// should we trim the existing image tag and do a proper replace with
+		// the describe describe value
+		return imageVal + "-" + version
+	default:
+		return imageVal
 	}
-	if format == BranchAndSHAFormat {
-		return imageVal + "-" + branch + "-" + SHA
-	}
-
-	return imageVal
 }