adds API_VERSION

.vscode/launch.json

@@ -9,8 +9,8 @@
             "type": "go",
             "request": "launch",
             "mode": "auto",
-            "program": "${workspaceFolder}/main.go",
-            "args": ["compose", "template", "up"]
+            "program": "${workspaceFolder}/cmd/build_test.go",
+            // "args": ["build"]
         }
     ]
 }

cmd/build.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"html/template"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -228,12 +229,22 @@ func generateDockerfileTemplate(wr io.Writer, filename string) {
 
 }
 
+func getApiVersion(filename string) string {
+
+	content, err := ioutil.ReadFile(filepath.Dir(filename) + "/API_VERSION")
+	if err != nil {
+		return ""
+	} else {
+		return string(content) + "-"
+	}
+}
+
 // getTag determines the string used for the docker image tag that gets referenced in the registry.
 // This is typically just the directory name the dockerfile resides in, but can be modified by either
 // using a variant in the filename (detailed below) or by using a git branch other than the default
 func getTag(filename string) string {
 
-	var tag string = filepath.Base(filepath.Dir(filename)) + getVariant(filename)
+	var tag string = getApiVersion(filename) + filepath.Base(filepath.Dir(filename)) + getVariant(filename)
 
 	if DockerRegistry != "" {
 		return DockerRegistry + ":" + tag

cmd/build_test.go

@@ -184,7 +184,7 @@ func Test_buildCmdOneArgWithImagesOutputOnlyWithTagReal(t *testing.T) {
 
 	var actual = buildImage("../examples/images/example/Dockerfile")
 
-	if actual != "superterran/mach:example" {
+	if actual != "superterran/mach:v1-example" {
 		assert.FailNowf(t, "mach tag returned as expected, %s", actual)
 	}
 }
@@ -196,7 +196,7 @@ func Test_buildCmdOneArgWithImagesOutputOnlyWithTagRealTemplate(t *testing.T) {
 
 	var actual = buildImage("../examples/images/example/Dockerfile-template.tpl")
 
-	if actual != "superterran/mach:example-template" {
+	if actual != "superterran/mach:v1-example-template" {
 		assert.FailNowf(t, "mach tag returned as expected, %s", actual)
 	}
 }
@@ -208,7 +208,7 @@ func Test_buildCmdOneArgWithImagesOutputOnlyWithTagRealOutputOnly(t *testing.T)
 
 	var actual = buildImage("../examples/images/example/Dockerfile")
 
-	if actual != "superterran/mach:example" {
+	if actual != "superterran/mach:v1-example" {
 		assert.FailNowf(t, "mach tag returned as expected, %s", actual)
 	}
 }
@@ -220,7 +220,7 @@ func Test_buildCmdOneArgWithImagesOutputOnlyWithTagRealTemplateOutputOnly(t *tes
 
 	var actual = buildImage("../examples/images/example/Dockerfile-template.tpl")
 
-	if actual != "superterran/mach:example-template" {
+	if actual != "superterran/mach:v1-example-template" {
 		assert.FailNowf(t, "mach tag returned as expected, %s", actual)
 	}
 }

examples/images/example/API_VERSION

@@ -0,0 +1 @@
+v1