// File generates an `/etc/coreos/update.conf` file (if any update
// configuration options are set in cloud-config) by either rewriting the
// existing file on disk, or starting from `/usr/share/coreos/update.conf`
func (uc Update) File() (*File, error) {
if config.IsZero(uc.Update) {
return nil, nil
}
if err := config.AssertStructValid(uc.Update); err != nil {
return nil, err
}
// Generate the list of possible substitutions to be performed based on the options that are configured
subs := map[string]string{}
uct := reflect.TypeOf(uc.Update)
ucv := reflect.ValueOf(uc.Update)
for i := 0; i < uct.NumField(); i++ {
val := ucv.Field(i).String()
if val == "" {
continue
}
env := uct.Field(i).Tag.Get("env")
subs[env] = fmt.Sprintf("%s=%s", env, val)
}
conf, err := uc.ReadConfig()
if err != nil {
return nil, err
}
scanner := bufio.NewScanner(conf)
var out string
for scanner.Scan() {
line := scanner.Text()
for env, value := range subs {
if strings.HasPrefix(line, env) {
line = value
delete(subs, env)
break
}
}
out += line
out += "\n"
if err := scanner.Err(); err != nil {
return nil, err
}
}
for _, key := range sortedKeys(subs) {
out += subs[key]
out += "\n"
}
return &File{config.File{
Path: path.Join("etc", "coreos", "update.conf"),
RawFilePermissions: "0644",
Content: out,
}}, nil
}
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
}