Added function to pull config from .env.

Author: doublehops

.env

@@ -1,4 +1,6 @@
 
+PORT=8088
+
 MYSQL_HOST=db
 MYSQL_ROOT_PASSWORD=pass12
 MYSQL_DATABASE=dhapi

cmd/server/run.go

@@ -36,6 +36,8 @@ func run() error {
 		return fmt.Errorf("error starting main. %s", err.Error())
 	}
 
+	fmt.Printf(">>>>>>>>>>>>>> HOST: %s\n", cfg.DB.Host)
+
 	// Setup logger.
 	l, err := logga.New(&cfg.Logging)
 	if err != nil {

config.json

@@ -1,14 +1,14 @@
 {
   "host": {
-    "port": "8088"
+    "port": "ENV:PORT"
   },
   "logging": {
     "writer": "stdout",
     "logLevel": "DEBUG",
     "outputFormat": "text"
   },
   "database": {
-    "host": "localhost",
+    "host": "ENV:MYSQL_HOST",
     "name": "dhapi",
     "user": "dev",
     "password": "pass12"

go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/jinzhu/copier v0.4.0
 	github.com/jmoiron/sqlx v1.4.0
+	github.com/joho/godotenv v1.5.1
 	github.com/julienschmidt/httprouter v1.3.0
 	github.com/mythrnr/httprouter-group v0.9.1
 	github.com/stretchr/testify v1.9.0

go.sum

@@ -12,6 +12,8 @@ github.com/jinzhu/copier v0.4.0 h1:w3ciUoD19shMCRargcpm0cm91ytaBhDvuRpz1ODO/U8=
 github.com/jinzhu/copier v0.4.0/go.mod h1:DfbEm0FYsaqBcKcFuvmOZb218JkPGtvSHsKg8S8hyyg=
 github.com/jmoiron/sqlx v1.4.0 h1:1PLqN7S1UYp5t4SrVVnt4nUVNemrDAtxlulVe+Qgm3o=
 github.com/jmoiron/sqlx v1.4.0/go.mod h1:ZrZ7UsYB/weZdl2Bxg6jCRO9c3YHl8r3ahlKmRT4JLY=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=

internal/config/config.go

@@ -6,6 +6,10 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"reflect"
+	"strings"
+
+	"github.com/joho/godotenv"
 )
 
 type Config struct {
@@ -39,6 +43,11 @@ type DB struct {
 func New(configFile string) (*Config, error) {
 	log.Printf("Loading config from file: %s", configFile)
 
+	err := godotenv.Load()
+	if err != nil {
+		log.Println("Unable to load .env")
+	}
+
 	var c Config
 
 	pwd, _ := os.Getwd()
@@ -58,9 +67,42 @@ func New(configFile string) (*Config, error) {
 		return nil, err
 	}
 
+	resolveEnvInStruct(&c)
+
 	if c.DB.Host == "" || c.DB.Name == "" || c.DB.User == "" || c.DB.Pass == "" {
 		return &c, fmt.Errorf("some configuration is missing")
 	}
 
 	return &c, nil
 }
+
+// resolveEnvInStruct will recursively look through config and replace any values with `ENV:XXX` with the
+// corresponding value found in `.env`.
+func resolveEnvInStruct(s interface{}) {
+	val := reflect.ValueOf(s)
+
+	if val.Kind() != reflect.Ptr || val.Elem().Kind() != reflect.Struct {
+		return
+	}
+	val = val.Elem()
+	// typ := val.Type()
+
+	for i := 0; i < val.NumField(); i++ {
+		field := val.Field(i)
+		// fieldType := typ.Field(i)
+
+		switch field.Kind() {
+		case reflect.String:
+			if field.CanSet() && strings.HasPrefix(field.String(), "ENV:") {
+				envKey := strings.TrimPrefix(field.String(), "ENV:")
+				if envVal, ok := os.LookupEnv(envKey); ok {
+					field.SetString(envVal)
+				} else {
+					fmt.Printf("Warning: env var %s not set\n", envKey)
+				}
+			}
+		case reflect.Struct:
+			resolveEnvInStruct(field.Addr().Interface())
+		}
+	}
+}