In this section, I create separate config files (yaml) for the development environment and docker environment, then make a config package to read configuration from yaml files.
To see this session project you can visit Session 4 GitHub repo URL.
Create config files
In the first step, we need to make three config files for the docker, production, and development environments in src/config path:
1. config-development.yml
server:
internalPort: 5005
externalPort: 5005
runMode: debug
logger:
filePath: ../logs/
encoding: json
level: debug
logger: zap
cors:
allowOrigins: "*"
postgres:
host: localhost
port: 5432
user: postgres
password: admin
dbName: car_sale_db
sslMode: disable
maxIdleConns: 15
maxOpenConns: 100
connMaxLifetime: 5
redis:
host: localhost
port: 6379
password: password
db: 0
dialTimeout: 5
readTimeout: 5
writeTimeout: 5
poolSize: 10
poolTimeout: 15
idleCheckFrequency: 500
password:
includeChars: true
includeDigits: true
minLength: 6
maxLength: 64
includeUppercase: true
includeLowercase: true
otp:
expireTime: 120
digits: 6
limiter: 100
jwt:
secret: "mySecretKey"
refreshSecret: "mySecretKey"
accessTokenExpireDuration: 1440
refreshTokenExpireDuration: 60
2. config-docker.yml
server:
internalPort: 5000
externalPort: 0
runMode: release
logger:
filePath: /app/logs/
encoding: json
level: debug
logger: zap
cors:
allowOrigins: "*"
postgres:
host: postgres_container
port: 5432
user: postgres
password: admin
dbName: car_sale_db
sslMode: disable
maxIdleConns: 15
maxOpenConns: 100
connMaxLifetime: 5
redis:
host: redis_container
port: 6379
password: password
db: 0
dialTimeout: 5
readTimeout: 5
writeTimeout: 5
poolSize: 10
poolTimeout: 15
idleCheckFrequency: 500
password:
includeChars: true
includeDigits: true
minLength: 6
maxLength: 64
includeUppercase: true
includeLowercase: true
otp:
expireTime: 120
digits: 6
limiter: 100
jwt:
secret: "mySecretKey"
refreshSecret: "mySecretKey"
accessTokenExpireDuration: 60
refreshTokenExpireDuration: 60
3. config-production.yml
server:
internalPort: 5010
externalPort: 5010
runMode: release
logger:
filePath: logs/
encoding: json
level: debug
logger: zap
cors:
allowOrigins: "*"
postgres:
host: localhost
port: 5432
user: postgres
password: admin
dbName: car_sale_db
sslMode: disable
maxIdleConns: 15
maxOpenConns: 100
connMaxLifetime: 5
redis:
host: localhost
port: 6379
password: password
db: 0
dialTimeout: 5
readTimeout: 5
writeTimeout: 5
poolSize: 10
poolTimeout: 15
idleCheckFrequency: 500
password:
includeChars: true
includeDigits: true
minLength: 6
maxLength: 64
includeUppercase: true
includeLowercase: true
otp:
expireTime: 120
digits: 6
limiter: 100
jwt:
secret: "mySecretKey"
refreshSecret: "mySecretKey"
accessTokenExpireDuration: 1440
refreshTokenExpireDuration: 60
4. Config structure in go
All configuration of the project must be placed in config-{env}.yml files. For now, server, logger, postgres, cors, and Redis configurations are placed in this file and will be completed later.
Now it's time to start making config.go file to the central point of the project environment the configuration management. this file is placed in src/config directory. First, we need to create structs corresponding to the config sections:
type Config struct {
Server ServerConfig
Postgres PostgresConfig
Redis RedisConfig
Password PasswordConfig
Cors CorsConfig
Logger LoggerConfig
Otp OtpConfig
JWT JWTConfig
}
type ServerConfig struct {
InternalPort string
ExternalPort string
RunMode string
}
type LoggerConfig struct {
FilePath string
Encoding string
Level string
Logger string
}
type PostgresConfig struct {
Host string
Port string
User string
Password string
DbName string
SSLMode string
MaxIdleConns int
MaxOpenConns int
ConnMaxLifetime time.Duration
}
type RedisConfig struct {
Host string
Port string
Password string
Db string
DialTimeout time.Duration
ReadTimeout time.Duration
WriteTimeout time.Duration
IdleCheckFrequency time.Duration
PoolSize int
PoolTimeout time.Duration
}
type PasswordConfig struct {
IncludeChars bool
IncludeDigits bool
MinLength int
MaxLength int
IncludeUppercase bool
IncludeLowercase bool
}
type CorsConfig struct {
AllowOrigins string
}
type OtpConfig struct {
ExpireTime time.Duration
Digits int
Limiter time.Duration
}
type JWTConfig struct {
AccessTokenExpireDuration time.Duration
RefreshTokenExpireDuration time.Duration
Secret string
RefreshSecret string
}
5. Config functions
In this project, we use viper package to manage configurations. So first we should install the Viper package go get -u github.com/spf13/viper. Then run go mod tidy command to ensure that all imports are satisfied.
At this stage, we need some functions
5.1 Get config file path
this function returns a file path based environment.
func getConfigPath(env string) string {
if env == "docker" {
return "/app/config/config-docker"
} else if env == "production" {
return "/config/config-production"
} else {
return "/config/config-development"
}
}
5.2 Load config file with Viper
After the config file was found, we needed to load the config file with Viper based specified file type.
func LoadConfig(filename string, fileType string) (*viper.Viper, error) {
v := viper.New()
v.SetConfigType(fileType)
v.SetConfigName(filename)
v.AddConfigPath(".")
v.AutomaticEnv()
err := v.ReadInConfig()
if err != nil {
log.Printf("Unable to read config: %v", err)
if _, ok := err.(viper.ConfigFileNotFoundError); ok {
return nil, errors.New("config file not found")
}
return nil, err
}
return v, nil
}
5.3 Parse Viper config
In this section, we should Unmarshal Viper config to the custom Config type declared in section 4. If this instruction was successful means the file is parsed and can be used.
func ParseConfig(v *viper.Viper) (*Config, error) {
var cfg Config
err := v.Unmarshal(&cfg)
if err != nil {
log.Printf("Unable to parse config: %v", err)
return nil, err
}
return &cfg, nil
}
5.4 Get config file from other layers
Finally, we write a function that is exposed to other layers to using config struct. This function returns a pointer of the config struct. Furthermore, some swagger port settings are handled in this function and I will explain about it in the next sections.
func GetConfig() *Config {
cfgPath := getConfigPath(os.Getenv("APP_ENV"))
v, err := LoadConfig(cfgPath, "yml")
if err != nil {
log.Fatalf("Error in load config %v", err)
}
cfg, err := ParseConfig(v)
envPort := os.Getenv("PORT")
if envPort != ""{
cfg.Server.ExternalPort = envPort
log.Printf("Set external port from environment -> %s", cfg.Server.ExternalPort)
}else{
cfg.Server.ExternalPort = cfg.Server.InternalPort
log.Printf("Set external port from environment -> %s", cfg.Server.ExternalPort)
}
if err != nil {
log.Fatalf("Error in parse config %v", err)
}
return cfg
}
This is the final version of the config.go file:
package config
import (
"errors"
"log"
"os"
"time"
"github.com/spf13/viper"
)
type Config struct {
Server ServerConfig
Postgres PostgresConfig
Redis RedisConfig
Password PasswordConfig
Cors CorsConfig
Logger LoggerConfig
Otp OtpConfig
JWT JWTConfig
}
type ServerConfig struct {
InternalPort string
ExternalPort string
RunMode string
}
type LoggerConfig struct {
FilePath string
Encoding string
Level string
Logger string
}
type PostgresConfig struct {
Host string
Port string
User string
Password string
DbName string
SSLMode string
MaxIdleConns int
MaxOpenConns int
ConnMaxLifetime time.Duration
}
type RedisConfig struct {
Host string
Port string
Password string
Db string
DialTimeout time.Duration
ReadTimeout time.Duration
WriteTimeout time.Duration
IdleCheckFrequency time.Duration
PoolSize int
PoolTimeout time.Duration
}
type PasswordConfig struct {
IncludeChars bool
IncludeDigits bool
MinLength int
MaxLength int
IncludeUppercase bool
IncludeLowercase bool
}
type CorsConfig struct {
AllowOrigins string
}
type OtpConfig struct {
ExpireTime time.Duration
Digits int
Limiter time.Duration
}
type JWTConfig struct {
AccessTokenExpireDuration time.Duration
RefreshTokenExpireDuration time.Duration
Secret string
RefreshSecret string
}
func GetConfig() *Config {
cfgPath := getConfigPath(os.Getenv("APP_ENV"))
v, err := LoadConfig(cfgPath, "yml")
if err != nil {
log.Fatalf("Error in load config %v", err)
}
cfg, err := ParseConfig(v)
envPort := os.Getenv("PORT")
if envPort != ""{
cfg.Server.ExternalPort = envPort
log.Printf("Set external port from environment -> %s", cfg.Server.ExternalPort)
}else{
cfg.Server.ExternalPort = cfg.Server.InternalPort
log.Printf("Set external port from environment -> %s", cfg.Server.ExternalPort)
}
if err != nil {
log.Fatalf("Error in parse config %v", err)
}
return cfg
}
func ParseConfig(v *viper.Viper) (*Config, error) {
var cfg Config
err := v.Unmarshal(&cfg)
if err != nil {
log.Printf("Unable to parse config: %v", err)
return nil, err
}
return &cfg, nil
}
func LoadConfig(filename string, fileType string) (*viper.Viper, error) {
v := viper.New()
v.SetConfigType(fileType)
v.SetConfigName(filename)
v.AddConfigPath(".")
v.AutomaticEnv()
err := v.ReadInConfig()
if err != nil {
log.Printf("Unable to read config: %v", err)
if _, ok := err.(viper.ConfigFileNotFoundError); ok {
return nil, errors.New("config file not found")
}
return nil, err
}
return v, nil
}
func getConfigPath(env string) string {
if env == "docker" {
return "/app/config/config-docker"
} else if env == "production" {
return "/config/config-production"
} else {
return "/config/config-development"
}
}
In the end, I want to load the config from the config file and read the webserver port from the config instead of hard-coding.
For example, I made some changes in src/api/api.go file. First append cfg := config.GetConfig() to start of InitServer function and then load the webserver port from config r.Run(fmt.Sprintf(":%s", cfg.Server.Port)).
This is the final version of api.go file:
package api
import (
"fmt"
"github.com/gin-gonic/gin"
"github.com/naeemaei/golang-clean-web-api/api/routers"
"github.com/naeemaei/golang-clean-web-api/config" // Added
)
func InitServer(){
cfg := config.GetConfig() // Added
r := gin.New()
r.Use(gin.Logger(), gin.Recovery())
v1 := r.Group("/api/v1/")
{
health := v1.Group("/health")
routers.Health(health)
}
if err := r.Run(fmt.Sprintf(":%s", cfg.Server.InternalPort)); err != nil {
panic(err)
} // Added
}
Now we can run the project with the go run cmd/main.go command from src directory.
In the next article, I will make a simple endpoint and explain how to validate the requests and how works validators in gin.
Top comments (1)
Very helpful & nice article.
I want to ask something.
Where do we put
APP_ENVand what is the value for that key?Thanks