src/helpers/config_loader.go

@@ -0,0 +1,129 @@
+package helpers
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+)
+
+type ConfigParameter struct {
+	EnvVarName   string `json:"env_var_name"`
+	ConfFilePath string `json:"conf_file_path"`
+	DefaultValue string `json:"default_value"`
+	FailIfAbsent bool   `json:"fail_if_absent"`
+}
+
+type Configuration struct {
+	VstpOn   bool   `json:"vstp_on"`
+	NrodUser string `json:"nrod_user"`
+	NrodPass string `json:"nrod_pass"`
+	DbHost   string `json:"db_host"`
+	DbPass   string `json:"db_pass"`
+	DbUser   string `json:"db_user"`
+	DbPort   string `json:"db_port"`
+}
+
+func LoadConfig() (*Configuration, error) {
+	configParams := map[string]ConfigParameter{
+		"vstp_on": {
+			EnvVarName:   "OWL_VSTP_ON",
+			ConfFilePath: "/owl/conf/vstp/on",
+			DefaultValue: "on",
+			FailIfAbsent: false,
+		},
+		"nrod_user": {
+			EnvVarName:   "OWL_NROD_USER",
+			ConfFilePath: "/owl/conf/nrod/user",
+			FailIfAbsent: true,
+		},
+		"nrod_pass": {
+			EnvVarName:   "OWL_NROD_PASS",
+			ConfFilePath: "/owl/conf/nrod/pass",
+			FailIfAbsent: true,
+		},
+		"db_host": {
+			EnvVarName:   "OWL_DB_HOST",
+			ConfFilePath: "/owl/conf/db/host",
+			DefaultValue: "localhost",
+			FailIfAbsent: false,
+		},
+		"db_port": {
+			EnvVarName:   "OWL_DB_PORT",
+			ConfFilePath: "/owl/conf/db/port",
+			DefaultValue: "27017",
+			FailIfAbsent: false,
+		},
+		"db_user": {
+			EnvVarName:   "OWL_DB_USER",
+			ConfFilePath: "/owl/conf/db/user",
+			FailIfAbsent: true,
+		},
+		"db_pass": {
+			EnvVarName:   "OWL_DB_PASS",
+			ConfFilePath: "/owl/conf/db/pass",
+			FailIfAbsent: true,
+		},
+	}
+
+	config := &Configuration{}
+
+	for key, param := range configParams {
+		if val, ok := os.LookupEnv(param.EnvVarName); ok {
+			config.setConfigValue(key, val)
+			continue
+		}
+
+		if data, err := ioutil.ReadFile(param.ConfFilePath); err == nil {
+			config.setConfigValue(key, string(data))
+			continue
+		}
+
+		if param.DefaultValue != "" {
+			config.setConfigValue(key, param.DefaultValue)
+			continue
+		}
+
+		if param.FailIfAbsent {
+			return nil, errors.New("Failed to load configuration: " + key + " is required but not set")
+		}
+	}
+
+	return config, nil
+}
+
+func (c *Configuration) setConfigValue(key, value string) {
+	switch key {
+	case "nrod_user":
+		c.NrodUser = value
+	case "nrod_pass":
+		c.NrodPass = value
+	case "db_host":
+		c.DbHost = value
+	case "db_port":
+		c.DbPort = value
+	case "db_user":
+		c.DbUser = value
+	case "db_pass":
+		c.DbPass = value
+	case "vstp_on":
+		if value == "on" {
+			c.VstpOn = true
+		} else {
+			c.VstpOn = false
+		}
+	}
+}
+
+func (c *Configuration) PrintConfig() {
+	if os.Getenv("DEBUG") == "true" {
+		fmt.Println("Configuration:")
+		fmt.Println("VstpOn: ", c.VstpOn)
+		fmt.Println("NrodUser: ", c.NrodUser)
+		fmt.Println("NrodPass: ", c.NrodPass)
+		fmt.Println("DbHost: ", c.DbHost)
+		fmt.Println("DbUser: ", c.DbUser)
+		fmt.Println("DbPass: ", c.DbPass)
+		fmt.Println("DbPort: ", c.DbPort)
+	}
+}

src/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
@@ -13,6 +14,14 @@ import (
 )
 
 func main() {
+
+	cfg, err := helpers.LoadConfig()
+	if err != nil {
+		fmt.Println("Error loading configuration", err)
+		return
+	}
+	cfg.PrintConfig()
+
 	log.Msg.Info("Initialised OwlBoard timetable-mgr " + helpers.Version)
 
 	defer cleanup()