Adding Support for Environment variable prefixes

README.md

@@ -170,7 +170,7 @@ the value will be read each time it is accessed. It does not fix the
 value when the BindEnv is called.
 
 
-AutomaticEnv is intended to be a convience helper. It will look for all
+AutomaticEnv is intended to be a convenience helper. It will look for all
 keys that have been set (via defaults, config file, flag, or remote key
 value) and call BindEnv on that key. It does
 not simply import all ENV variables. Because of this behavior it’s

viper.go

@@ -74,6 +74,7 @@ type viper struct {
 	configName string
 	configFile string
 	configType string
+	envPrefix  string
 
 	config   map[string]interface{}
 	override map[string]interface{}
@@ -125,6 +126,22 @@ func (v *viper) SetConfigFile(in string) {
 	}
 }
 
+// Define a prefix that ENVIRONMENT variables will use.
+func SetEnvPrefix(in string) { v.SetEnvPrefix(in) }
+func (v *viper) SetEnvPrefix(in string) {
+	if in != "" {
+		v.envPrefix = in
+	}
+}
+
+func (v *viper) mergeWithEnvPrefix(in string) string {
+	if v.envPrefix != "" {
+		return v.envPrefix + "_" + in
+	}
+
+	return in
+}
+
 // Return the config file used
 func ConfigFileUsed() string            { return v.ConfigFileUsed() }
 func (v *viper) ConfigFileUsed() string { return v.configFile }
@@ -342,6 +359,7 @@ func (v *viper) BindPFlag(key string, flag *pflag.Flag) (err error) {
 // Binds a viper key to a ENV variable
 // ENV variables are case sensitive
 // If only a key is provided, it will use the env key matching the key, uppercased.
+// EnvPrefix will be used when set when env name is not provided.
 func BindEnv(input ...string) (err error) { return v.BindEnv(input...) }
 func (v *viper) BindEnv(input ...string) (err error) {
 	var key, envkey string
@@ -352,7 +370,7 @@ func (v *viper) BindEnv(input ...string) (err error) {
 	key = strings.ToLower(input[0])
 
 	if len(input) == 1 {
-		envkey = strings.ToUpper(key)
+		envkey = strings.ToUpper(v.mergeWithEnvPrefix(key))
 	} else {
 		envkey = input[1]
 	}

viper_test.go

@@ -67,6 +67,49 @@ var remoteExample = []byte(`{
 "newkey":"remote"
 }`)
 
+func initConfigs() {
+	Reset()
+	SetConfigType("yaml")
+	r := bytes.NewReader(yamlExample)
+	marshalReader(r, v.config)
+
+	SetConfigType("json")
+	r = bytes.NewReader(jsonExample)
+	marshalReader(r, v.config)
+
+	SetConfigType("toml")
+	r = bytes.NewReader(tomlExample)
+	marshalReader(r, v.config)
+
+	SetConfigType("json")
+	remote := bytes.NewReader(remoteExample)
+	marshalReader(remote, v.kvstore)
+}
+
+func initYAML() {
+	Reset()
+	SetConfigType("yaml")
+	r := bytes.NewReader(yamlExample)
+
+	marshalReader(r, v.config)
+}
+
+func initJSON() {
+	Reset()
+	SetConfigType("json")
+	r := bytes.NewReader(jsonExample)
+
+	marshalReader(r, v.config)
+}
+
+func initTOML() {
+	Reset()
+	SetConfigType("toml")
+	r := bytes.NewReader(tomlExample)
+
+	marshalReader(r, v.config)
+}
+
 //stubs for PFlag Values
 type stringValue string
 
@@ -139,34 +182,23 @@ func TestAliasInConfigFile(t *testing.T) {
 }
 
 func TestYML(t *testing.T) {
-	Reset()
-	SetConfigType("yml")
-	r := bytes.NewReader(yamlExample)
-
-	marshalReader(r, v.config)
+	initYAML()
 	assert.Equal(t, "steve", Get("name"))
 }
 
 func TestJSON(t *testing.T) {
-	SetConfigType("json")
-	r := bytes.NewReader(jsonExample)
-
-	marshalReader(r, v.config)
+	initJSON()
 	assert.Equal(t, "0001", Get("id"))
 }
 
 func TestTOML(t *testing.T) {
-	SetConfigType("toml")
-	r := bytes.NewReader(tomlExample)
-
-	marshalReader(r, v.config)
+	initTOML()
 	assert.Equal(t, "TOML Example", Get("title"))
 }
 
 func TestRemotePrecedence(t *testing.T) {
-	SetConfigType("json")
-	r := bytes.NewReader(jsonExample)
-	marshalReader(r, v.config)
+	initJSON()
+
 	remote := bytes.NewReader(remoteExample)
 	assert.Equal(t, "0001", Get("id"))
 	marshalReader(remote, v.kvstore)
@@ -180,9 +212,8 @@ func TestRemotePrecedence(t *testing.T) {
 }
 
 func TestEnv(t *testing.T) {
-	SetConfigType("json")
-	r := bytes.NewReader(jsonExample)
-	marshalReader(r, v.config)
+	initJSON()
+
 	BindEnv("id")
 	BindEnv("f", "FOOD")
 
@@ -199,10 +230,32 @@ func TestEnv(t *testing.T) {
 	assert.Equal(t, "crunk", Get("name"))
 }
 
+func TestEnvPrefix(t *testing.T) {
+	initJSON()
+
+	SetEnvPrefix("foo") // will be uppercased automatically
+	BindEnv("id")
+	BindEnv("f", "FOOD") // not using prefix
+
+	os.Setenv("FOO_ID", "13")
+	os.Setenv("FOOD", "apple")
+	os.Setenv("FOO_NAME", "crunk")
+
+	assert.Equal(t, "13", Get("id"))
+	assert.Equal(t, "apple", Get("f"))
+	assert.Equal(t, "Cake", Get("name"))
+
+	AutomaticEnv()
+
+	assert.Equal(t, "crunk", Get("name"))
+}
+
 func TestAllKeys(t *testing.T) {
+	initConfigs()
+
 	ks := sort.StringSlice{"title", "newkey", "owner", "name", "beard", "ppu", "batters", "hobbies", "clothing", "age", "hacker", "id", "type", "eyes"}
 	dob, _ := time.Parse(time.RFC3339, "1979-05-27T07:32:00Z")
-	all := map[string]interface{}{"hacker": true, "beard": true, "newkey": "remote", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "ppu": 0.55, "clothing": map[interface{}]interface{}{"jacket": "leather", "trousers": "denim"}, "name": "crunk", "owner": map[string]interface{}{"organization": "MongoDB", "Bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "id": "13", "title": "TOML Example", "age": 35, "type": "donut", "eyes": "brown"}
+	all := map[string]interface{}{"owner": map[string]interface{}{"organization": "MongoDB", "Bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "title": "TOML Example", "ppu": 0.55, "eyes": "brown", "clothing": map[interface{}]interface{}{"trousers": "denim", "jacket": "leather"}, "id": "0001", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hacker": true, "beard": true, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "age": 35, "type": "donut", "newkey": "remote", "name": "Cake"}
 
 	var allkeys sort.StringSlice
 	allkeys = AllKeys()