126 lines
3.1 KiB
Go
126 lines
3.1 KiB
Go
package config
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import (
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"flag"
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"log"
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"os"
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"reflect"
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"strconv"
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"time"
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)
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// getEnvString returns string from environment variable
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func getEnvString(env, def string) (val string) { //nolint:deadcode
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val = os.Getenv(env)
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if val == "" {
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return def
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}
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return
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}
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// getEnvInt returns int from environment variable
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func getEnvInt(env string, def int) (ret int) {
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val := os.Getenv(env)
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if val == "" {
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return def
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}
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ret, err := strconv.Atoi(val)
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if err != nil {
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log.Fatalf("[ERROR] Environment variable is not numeric: %v\n", env)
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}
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return
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}
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// getEnvBool returns boolean from environment variable
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func getEnvBool(env string, def bool) bool {
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var (
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err error
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retVal bool
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val = os.Getenv(env)
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)
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if len(val) == 0 {
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return def
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} else {
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retVal, err = strconv.ParseBool(val)
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if err != nil {
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log.Fatalf("[ERROR] Environment variable is not boolean: %v\n", env)
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}
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}
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return retVal
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}
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// Init initializes the application configuration by reading default values from the struct's tags
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// and environment variables. Tags processed by this process are as follows:
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// `ignored:"true" env:"ENVIRONMENT_VARIABLE" default:"default value"`
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func Init() *Config {
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cfg := DefaultConfig()
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cfgInfo, err := getStructInfo(cfg)
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if err != nil {
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log.Fatalf("[FATAL] %v", err)
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}
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for _, info := range cfgInfo {
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switch info.Type.String() {
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case "string":
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var dv string
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if info.DefaultValue != nil {
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dv = info.DefaultValue.(string)
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}
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p := reflect.ValueOf(cfg).Elem().FieldByName(info.Name).Addr().Interface().(*string)
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flag.StringVar(p, info.Name, getEnvString(info.Name, dv), "("+info.Key+")")
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case "bool":
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var dv bool
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if info.DefaultValue != nil {
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dv = info.DefaultValue.(bool)
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}
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p := reflect.ValueOf(cfg).Elem().FieldByName(info.Name).Addr().Interface().(*bool)
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flag.BoolVar(p, info.Name, getEnvBool(info.Name, dv), "("+info.Key+")")
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case "int":
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var dv int
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if info.DefaultValue != nil {
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dv = int(info.DefaultValue.(int64))
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}
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p := reflect.ValueOf(cfg).Elem().FieldByName(info.Name).Addr().Interface().(*int)
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flag.IntVar(p, info.Name, getEnvInt(info.Name, dv), "("+info.Key+")")
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}
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}
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flag.Parse()
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// set logging level
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cfg.setLogLevel()
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// validate some required values are defined.
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// need to break this out to a required:"true" struct tag
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if err = cfg.validate(); err != nil {
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log.Fatalf("[FATAL] %v", err)
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}
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// timezone & format configuration
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cfg.TZoneUTC, _ = time.LoadLocation("UTC")
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if err != nil {
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log.Fatalf("[ERROR] Unable to parse timezone string. Please use one of the timezone database values listed here: %s", "https://en.wikipedia.org/wiki/List_of_tz_database_time_zones")
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}
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cfg.TZoneLocal, err = time.LoadLocation(cfg.TimeZoneLocal)
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if err != nil {
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log.Fatalf("[ERROR] Unable to parse timezone string. Please use one of the timezone database values listed here: %s", "https://en.wikipedia.org/wiki/List_of_tz_database_time_zones")
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}
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time.Now().Format(cfg.TimeFormat)
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// print running config
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cfg.printRunningConfig(cfgInfo)
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log.Println("[INFO] initialization complete")
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return cfg
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}
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