Add a groupByMulti template function

Supports the use case of having multiple values stored in an env
var that are separated by a comma or other char.  For example,
w/ nginx-proxy, VIRTUAL_HOST=foo.example.com controls the virtual
host that will be setup.  If an container supported multiple
virtual host, it could not be done w/
VIRTUAL_HOST=foo.example.com,bar.example.com.

Author: jwilder

template.go

@@ -11,6 +11,21 @@ import (
 	"text/template"
 )
 
+func groupByMulti(entries []*RuntimeContainer, key, sep string) map[string][]*RuntimeContainer {
+	groups := make(map[string][]*RuntimeContainer)
+	for _, v := range entries {
+		value := deepGet(*v, key)
+		if value != nil {
+			items := strings.Split(value.(string), sep)
+			for _, item := range items {
+				groups[item] = append(groups[item], v)
+			}
+
+		}
+	}
+	return groups
+}
+
 func groupBy(entries []*RuntimeContainer, key string) map[string][]*RuntimeContainer {
 	groups := make(map[string][]*RuntimeContainer)
 	for _, v := range entries {
@@ -32,9 +47,10 @@ func contains(item map[string]string, key string) bool {
 func generateFile(config Config, containers []*RuntimeContainer) bool {
 	templatePath := config.Template
 	tmpl, err := template.New(filepath.Base(templatePath)).Funcs(template.FuncMap{
-		"contains": contains,
-		"groupBy":  groupBy,
-		"split":    strings.Split,
+		"contains":     contains,
+		"groupBy":      groupBy,
+		"groupByMulti": groupByMulti,
+		"split":        strings.Split,
 	}).ParseFiles(templatePath)
 	if err != nil {
 		log.Fatalf("unable to parse template: %s", err)

template_test.go

@@ -1,8 +1,6 @@
 package main
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestContains(t *testing.T) {
 	env := map[string]string{
@@ -56,3 +54,48 @@ func TestGroupByExitingKey(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestGroupByMulti(t *testing.T) {
+	containers := []*RuntimeContainer{
+		&RuntimeContainer{
+			Env: map[string]string{
+				"VIRTUAL_HOST": "demo1.localhost",
+			},
+			ID: "1",
+		},
+		&RuntimeContainer{
+			Env: map[string]string{
+				"VIRTUAL_HOST": "demo1.localhost,demo3.localhost",
+			},
+			ID: "2",
+		},
+		&RuntimeContainer{
+			Env: map[string]string{
+				"VIRTUAL_HOST": "demo2.localhost",
+			},
+			ID: "3",
+		},
+	}
+
+	groups := groupByMulti(containers, "Env.VIRTUAL_HOST", ",")
+	if len(groups) != 3 {
+		t.Fatalf("expected 3 got %d", len(groups))
+	}
+
+	if len(groups["demo1.localhost"]) != 2 {
+		t.Fatalf("expected 2 got %s", len(groups["demo1.localhost"]))
+	}
+
+	if len(groups["demo2.localhost"]) != 1 {
+		t.Fatalf("expected 1 got %s", len(groups["demo2.localhost"]))
+	}
+	if groups["demo2.localhost"][0].ID != "3" {
+		t.Fatalf("expected 2 got %s", groups["demo2.localhost"][0].ID)
+	}
+	if len(groups["demo3.localhost"]) != 1 {
+		t.Fatalf("expect 1 got %d", len(groups["demo3.localhost"]))
+	}
+	if groups["demo3.localhost"][0].ID != "2" {
+		t.Fatalf("expected 2 got %s", groups["demo3.localhost"][0].ID)
+	}
+}