move coreos-cloudinit into config/cloudinit

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

config/cloudinit/system/env.go

@@ -0,0 +1,52 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package system
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/rancher/os/config/cloudinit/config"
+)
+
+// serviceContents generates the contents for a drop-in unit given the config.
+// The argument must be a struct from the 'config' package.
+func serviceContents(e interface{}) string {
+	vars := getEnvVars(e)
+	if len(vars) == 0 {
+		return ""
+	}
+
+	out := "[Service]\n"
+	for _, v := range vars {
+		out += fmt.Sprintf("Environment=\"%s\"\n", v)
+	}
+	return out
+}
+
+func getEnvVars(e interface{}) []string {
+	et := reflect.TypeOf(e)
+	ev := reflect.ValueOf(e)
+
+	vars := []string{}
+	for i := 0; i < et.NumField(); i++ {
+		if val := ev.Field(i).Interface(); !config.IsZero(val) {
+			key := et.Field(i).Tag.Get("env")
+			vars = append(vars, fmt.Sprintf("%s=%v", key, val))
+		}
+	}
+
+	return vars
+}