README.md, Makefile, example

.travis.yml

@@ -10,4 +10,5 @@ env:
     - GO111MODULE=on
 
 script:
-  - go test -v
+  - make test
+  - make bench

Makefile

@@ -1,8 +1,11 @@
-test: ## Run unit tests
-	go test -count=1 -short ./...
+test:
+	go test -race -v ./...
 
-cover: dep
+bench:
+	go test -run="^$$" -bench=.
+
+cover:
 	go test $(shell go list ./... | grep -v /vendor/;) -cover -v
 
-dep: ## Get the dependencies
-	GO111MODULE=on go mod vendor
+dep:
+	GO111MODULE=on go mod vendor

README.md

@@ -1 +1,77 @@
 # go-config [![Build Status](https://travis-ci.org/Yalantis/go-config.svg?branch=master)](https://travis-ci.org/Yalantis/go-config)
+
+go-config allows to initialize configuration in flexible way using from default, file, environment variables value.  
+### Initialization
+Done in three steps:  
+  1. init with value from `default` tag
+  2. merge with config file if `filepath` is provided
+  3. override with environment variables which stored under `envconfig` tag
+
+### Supported file extensions
+- json
+
+### Supported types
+- Standard types: `bool`, `float`, `int`(`uint`), `slice`, `string`
+- `time.Duration`, `time.Time`: full support with aliases `config.Duration`, `config.Time`
+- Custom types, slice of custom types
+
+### Usage
+
+#### Default value
+```go
+type Server struct {
+    Addr string `default:"localhost:8080"`
+}
+```
+#### Environment value
+```go
+type Server struct {
+    Addr string `envconfig:"SERVER_ADDR"`
+}
+```
+#### Combined default, json, env
+```go
+type Server struct {
+    Addr string `json:"addr" envconfig:"SERVER_ADDR" default:"localhost:8080"`
+}
+```
+#### Slice
+Default strings separator is comma. 
+```
+REDIS_ADDR=127.0.0.1:6377,127.0.0.1:6378,127.0.0.1:6379
+```
+```go
+type Redis struct {
+    Addrs []string `json:"addrs" envconfig:"REDIS_ADDR" default:"localhost:6378,localhost:6379"`
+}
+```
+Slice of structs could be parsed from environment by defining `envprefix`.  
+Every ENV group override element stored at `index` of slice or append new one.  
+Sparse slices are not allowed.
+```go
+var cfg struct {
+...
+Replicas []Postgres `json:"replicas" envprefix:"REPLICAS"`
+...
+}
+```
+Environment key should has next pattern:  
+`${envprefix}_${index}_${envconfig}` or `${envprefix}_${index}_${StructFieldName}`
+```
+REPLICAS_0_POSTGRES_USER=replica REPLICAS_2_USER=replica
+```
+#### `time.Duration`, `time.Time`
+In case using json file you have to use aliases `config.Duration`, `config.Time`, that properly unmarshal it self
+```go
+type NATS struct {
+    ...
+    ReconnectInterval config.Duration `json:"reconnect_interval" envconfig:"NATS_RECONNECT_INTERVAL" default:"2s"`
+}
+```
+Otherwise `time.Duration`, `time.Time` might be used directly:
+```go
+var cfg struct {
+    ReadTimeout  time.Duration `envconfig:"READ_TIMEOUT"  default:"1s"`
+    WriteTimeout time.Duration `envconfig:"WRITE_TIMEOUT" default:"10s"`
+}
+```

apply_env_overrides.go

@@ -10,9 +10,9 @@ import (
 )
 
 var (
-	ErrDstNotSlice    = errors.New("dst must be a slice")
+	ErrNotSlice       = errors.New("should be a slice")
+	ErrNotSettable    = errors.New("should be settable")
 	ErrPrefixRequired = errors.New("prefix is required")
-	ErrDstUnsettable  = errors.New("unsetable dst value")
 )
 
 var camelCaseRegex = regexp.MustCompile("(^[A-Za-z])|_([A-Za-z])")
@@ -35,19 +35,19 @@ func applyEnvOverridesToSlice(prefix string, dst interface{}) error {
 		// fallback
 		rv = reflect.ValueOf(dst)
 		if rv.Kind() != reflect.Ptr {
-			return ErrDstNotPointer
+			return ErrNotPointer
 		}
 	}
 
 	riv := indirectWalk(rv)
 	rit := indirectType(riv.Type())
 
 	if rit.Kind() != reflect.Slice {
-		return ErrDstNotSlice
+		return ErrNotSlice
 	}
 
 	if !rv.CanSet() && !riv.CanSet() {
-		return fmt.Errorf("unsettable type: %s %s at prefix: %s", rv.Type(), riv.Type(), prefix)
+		return fmt.Errorf("not settable type: %s %s at prefix: %s: %v", rv.Type(), riv.Type(), prefix, ErrNotSettable)
 	}
 
 	parseKeyVal, err := regexp.Compile(prefix + "_(\\d+)_(\\w+)=(.+)")
@@ -132,12 +132,8 @@ func applyEnvOverridesToSlice(prefix string, dst interface{}) error {
 		return nil
 	}
 
-	if riv.CanSet() {
-		setPtrValue(riv, ptr, tmp)
-		return nil
-	}
-
-	return ErrDstUnsettable
+	setPtrValue(riv, ptr, tmp)
+	return nil
 }
 
 // setPtrValue set as Ptr or Value

apply_env_overrides_test.go

@@ -62,13 +62,13 @@ func TestApplyEnvOverridesToSlice(t *testing.T) {
 			name:   "not a pointer",
 			prefix: "PREFIX_S",
 			value:  []Payload{},
-			err:    ErrDstNotPointer,
+			err:    ErrNotPointer,
 		},
 		{
 			name:   "not a slice",
 			prefix: "PREFIX_S",
 			value:  new(int),
-			err:    ErrDstNotSlice,
+			err:    ErrNotSlice,
 		},
 		{
 			name:   "fail on time.ParseDuration",

config.go

@@ -14,8 +14,8 @@ import (
 )
 
 var (
-	ErrDstNotPointer = errors.New("dst should be a pointer")
-	ErrNotStruct     = errors.New("should be a structure")
+	ErrNotPointer = errors.New("should be a pointer")
+	ErrNotStruct  = errors.New("should be a structure")
 )
 
 var (
@@ -28,14 +28,15 @@ var (
 const (
 	envConfigTag = "envconfig"
 	envPrefixTag = "envprefix"
+	defaultTag   = "default"
 )
 
 // Init reads and init configuration to `config` variable, which must be a reference of struct
 func Init(config interface{}, filename string) error {
 	v := reflect.ValueOf(config)
 
 	if v.Kind() != reflect.Ptr {
-		return ErrDstNotPointer
+		return ErrNotPointer
 	}
 
 	v = reflect.Indirect(v)
@@ -106,7 +107,7 @@ func applyDefault(t reflect.StructField, v reflect.Value) error {
 		return nil
 	}
 
-	value, ok := t.Tag.Lookup("default")
+	value, ok := t.Tag.Lookup(defaultTag)
 	if !ok {
 		return nil
 	}
@@ -167,8 +168,11 @@ func applyEnv(v reflect.Value) error {
 }
 
 func applyEnvValue(t reflect.StructField, v reflect.Value) error {
-	if value, ok := t.Tag.Lookup(envPrefixTag); ok && indirectType(v.Type()).Kind() == reflect.Slice {
-		return applyEnvOverridesToSlice(value, v)
+	switch indirectType(v.Type()).Kind() {
+	case reflect.Slice:
+		if value, ok := t.Tag.Lookup(envPrefixTag); ok {
+			return applyEnvOverridesToSlice(value, v)
+		}
 	}
 
 	if v.Kind() == reflect.Struct && !isTime(v.Type()) {

config_test.go

@@ -31,7 +31,7 @@ func TestInit(t *testing.T) {
 			name:     "not a pointer",
 			filePath: "",
 			cfg:      cfg,
-			error:    ErrDstNotPointer.Error(),
+			error:    ErrNotPointer.Error(),
 		},
 		{
 			name:     "not a struct",

configuration_test.go

@@ -33,7 +33,7 @@ func TestInitOnConfiguration(t *testing.T) {
 			name:   "not pointer",
 			value:  Configuration{},
 			expect: Configuration{},
-			err:    ErrDstNotPointer,
+			err:    ErrNotPointer,
 		},
 		{
 			name:   "fail on time.ParseDuration",

env.go

@@ -1,8 +1,10 @@
 package config
 
-import "syscall"
+import "os"
 
-var lookupEnv = syscall.Getenv
-var environ = syscall.Environ
-var Setenv = syscall.Setenv
-var Unsetenv = syscall.Unsetenv
+var lookupEnv = os.LookupEnv
+var environ = os.Environ
+var Setenv = os.Setenv
+var Unsetenv = os.Unsetenv
+
+//var ExpandEnv = os.ExpandEnv

example_test.go

@@ -0,0 +1,77 @@
+package config_test
+
+import (
+	"fmt"
+	"github.com/Yalantis/go-config"
+	"log"
+	"time"
+)
+
+func init() {
+	// setup ENV
+	_ = config.Setenv("VERSION", "0.0.1")
+	_ = config.Setenv("REPLICAS_0_POSTGRES_USER", "replica0")
+	_ = config.Setenv("REPLICAS_0_POSTGRES_PORT", "5433")
+	_ = config.Setenv("REPLICAS_1_USER", "replica1")
+	_ = config.Setenv("REPLICAS_1_PORT", "5433")
+	_ = config.Setenv("REDIS_ADDR", "127.0.0.1:6377,127.0.0.1:6378,127.0.0.1:6379")
+	_ = config.Setenv("READ_TIMEOUT", "30s")
+}
+
+func ExampleInit() {
+	type Server struct {
+		Addr string `json:"addr" envconfig:"SERVER_ADDR" default:"localhost:8080"`
+	}
+
+	type Postgres struct {
+		Host     string `json:"host"     envconfig:"POSTGRES_HOST"     default:"localhost"`
+		Port     string `json:"port"     envconfig:"POSTGRES_PORT"     default:"5432"`
+		User     string `json:"user"     envconfig:"POSTGRES_USER"     default:"postgres"`
+		Password string `json:"password" envconfig:"POSTGRES_PASSWORD" default:"12345"`
+	}
+
+	type Redis struct {
+		Addrs []string `json:"addrs" envconfig:"REDIS_ADDR" default:"localhost:6379"`
+	}
+
+	type NATS struct {
+		ServerURL               string          `json:"server_url"                envconfig:"NATS_SERVER_URL"             default:"nats://localhost:4222"`
+		MaxReconnectionAttempts int             `json:"max_reconnection_attempts" envconfig:"NATS_MAX_RECONNECT_ATTEMPTS" default:"5"`
+		ReconnectInterval       config.Duration `json:"reconnect_interval"        envconfig:"NATS_RECONNECT_INTERVAL"     default:"2s"`
+	}
+
+	type Websocket struct {
+		Port string `json:"port" envconfig:"WEBSOCKET_PORT" default:"9876"`
+	}
+
+	var cfg struct {
+		Version   string     `envconfig:"VERSION" default:"0"`
+		Server    Server     `json:"server"`
+		Postgres  Postgres   `json:"postgres"`
+		Replicas  []Postgres `json:"replicas" envprefix:"REPLICAS"`
+		Redis     Redis      `json:"redis"`
+		NATS      NATS       `json:"nats"`
+		Websocket Websocket  `json:"websocket"`
+	}
+
+	if err := config.Init(&cfg, "testdata/config.json"); err != nil {
+		log.Fatalln(err)
+	}
+
+	fmt.Println(cfg)
+	// Output: {0.0.1 {localhost:8080} {localhost 5432 postgres 12345} [{localhost 5433 replica0 12345} {localhost 5433 replica1 12345}] {[127.0.0.1:6377 127.0.0.1:6378 127.0.0.1:6379]} {nats://localhost:4222 5 2000000000} {9876}}
+}
+
+func ExampleInitTimeout() {
+	var cfg struct {
+		ReadTimeout  time.Duration `envconfig:"READ_TIMEOUT"  default:"1s"`
+		WriteTimeout time.Duration `envconfig:"WRITE_TIMEOUT" default:"10s"`
+	}
+
+	if err := config.Init(&cfg, ""); err != nil {
+		log.Fatalln(err)
+	}
+
+	fmt.Println(cfg)
+	// Output: {30s 10s}
+}

go.mod

@@ -1,5 +1,5 @@
-module gitlab.yalantis.com/gophers/config
+module github.com/Yalantis/go-config
 
-require github.com/stretchr/testify v1.3.0
+go 1.13
 
-go 1.11+
+require github.com/stretchr/testify v1.4.0

go.sum

@@ -3,5 +3,9 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
-github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

testdata/config.json

@@ -6,18 +6,21 @@
     "password": "12345"
   },
   "redis": {
-    "addrs": "127.0.0.1:6374,127.0.0.1:6375,127.0.0.1:6376,127.0.0.1:6377,127.0.0.1:6378,127.0.0.1:6379",
+    "addrs": [
+      "127.0.0.1:6374",
+      "127.0.0.1:6375",
+      "127.0.0.1:6376",
+      "127.0.0.1:6377",
+      "127.0.0.1:6378",
+      "127.0.0.1:6379"
+    ],
     "password": "",
     "db": 1,
     "pool_size": 10
   },
   "nats": {
-    "server_urls": "nats://localhost:4222",
+    "server_url": "nats://localhost:4222",
     "max_reconnection_attempts": 5,
-    "reconnect_interval_sec": 2
-  },
-  "websocket": {
-    "port": "9876",
-    "in_messages_chan_size": 5000
+    "reconnect_interval": "2s"
   }
 }