Merge pull request #8 from num30/no-env-prefix

Don't use prefix for env vars by default

README.md

@@ -88,8 +88,7 @@ Config file type could be any type supported by  [viper](https://github.com/spf1
 
 To set a flag via environment variable, make all letters uppercase and replace '.' with '_' in path. For example: app.Server.Port -> APP_SERVER_PORT
 
-Environment variables are prefixed with `config name` by default. For example `NewConfReader("myconf")` will search for environment variables like `MYCONF_DB_HOST` 
-This behavior could be overridden by setting `NewConfReader("myconf").WithoutPrefix()`
+You can set a prefix for environment variables. For example `NewConfReader("myconf").WithPrefix("MYAPP")` will search for environment variables like `MYAPP_DB_HOST`
 
 ### Command Line Arguments :computer: 
 
@@ -128,7 +127,7 @@ For full list of validation tag refer to [validator](https://github.com/go-playg
     ```
     then we can set values for slice in the following ways:
     - environment variable
-        `export SLICE_SLICE="a,b"`
+        `export SLICE="a,b"`
     - command line argument
         `myapp --slice", "a", "--slice", "b"`
     - config file

config.go

@@ -45,7 +45,7 @@ func NewConfReader(configName string) *ConfReader {
 	return &ConfReader{
 		viper:        enviper.New(viper.New()),
 		configName:   configName,
-		envVarPrefix: strings.ToUpper(configName),
+		envVarPrefix: "",
 	}
 }
 
@@ -258,7 +258,8 @@ func (c *ConfReader) WithSearchDirs(s ...string) *ConfReader {
 	return c
 }
 
-func (c *ConfReader) WithoutPrefix() *ConfReader {
-	c.envVarPrefix = ""
+// WithPrefix sets the prefix for environment variables
+func (c *ConfReader) WithPrefix(prefix string) *ConfReader {
+	c.envVarPrefix = prefix
 	return c
 }

config_test.go

@@ -42,11 +42,11 @@ func Test_ConfigReader(t *testing.T) {
 
 	os.Args = []string{"get", "--id", "10", "--verbose", "--app.overriddenbyarg", fromArgVal}
 
-	os.Setenv("MYAPP_APP_FROMENVVAR", valFromVar)
-	defer os.Unsetenv("MYAPP_APP_FROMENVVAR")
+	os.Setenv("APP_FROMENVVAR", valFromVar)
+	defer os.Unsetenv("APP_FROMENVVAR")
 
-	os.Setenv("MYAPP_APP_OVERRIDDENBYEVNVAR", overriddenVar)
-	defer os.Unsetenv("MYAPP_APP_OVERRIDDENBYEVNVAR")
+	os.Setenv("APP_OVERRIDDENBYEVNVAR", overriddenVar)
+	defer os.Unsetenv("APP_OVERRIDDENBYEVNVAR")
 
 	// act
 	err := confReader.Read(nc)
@@ -82,7 +82,7 @@ func Test_ReadFromFile(t *testing.T) {
 func Test_EnvVarsNoPrefix(t *testing.T) {
 	resetFlags()
 	nc := &FullConfig{}
-	confReader := NewConfReader("myapp").WithoutPrefix()
+	confReader := NewConfReader("myapp")
 	os.Setenv("APP_FROMENVVAR", "valFromEnvVar")
 
 	err := confReader.Read(nc)
@@ -91,6 +91,19 @@ func Test_EnvVarsNoPrefix(t *testing.T) {
 	}
 }
 
+func Test_EnvVarsWithPrefix(t *testing.T) {
+	resetFlags()
+	nc := &FullConfig{}
+	confReader := NewConfReader("myapp").WithPrefix("MYAPP")
+	os.Setenv("MYAPP_APP_FROMENVVAR", "valFromEnvVar")
+	defer os.Unsetenv("APP_FROMENVVAR")
+
+	err := confReader.Read(nc)
+	if assert.NoError(t, err) {
+		assert.Equal(t, "valFromEnvVar", nc.App.FromEnvVar)
+	}
+}
+
 func Test_ReadFromJsonFile(t *testing.T) {
 	resetFlags()
 	nc := &FullConfig{}
@@ -165,8 +178,8 @@ func Test_Validation(t *testing.T) {
 
 	t.Run("passes", func(t *testing.T) {
 		resetFlags()
-		os.Setenv("MYAPP_HOST", "localhost")
-		defer os.Unsetenv("MYAPP_HOST")
+		os.Setenv("HOST", "localhost")
+		defer os.Unsetenv("HOST")
 		err := reader.Read(cf)
 		if assert.NoError(t, err) {
 			assert.Equal(t, "localhost", cf.Host)
@@ -254,8 +267,8 @@ func Test_Slice(t *testing.T) {
 
 	t.Run("envVar", func(t *testing.T) {
 		cfg := SliceConf{}
-		os.Setenv("SLICE_SLICE", "a,b,c")
-		defer os.Unsetenv("SLICE_SLICE")
+		os.Setenv("SLICE", "a,b,c")
+		defer os.Unsetenv("SLICE")
 		reader := NewConfReader("slice")
 		err := reader.Read(&cfg)
 		if assert.NoError(t, err) {

examples/main.go

@@ -32,7 +32,7 @@ func main() {
 	// Refer to myconf.yaml for file configuration
 
 	// Use env vars to set config keys
-	os.Setenv("MYCONF_FOO_DURATIONFROMENVVAR", "10m")
+	os.Setenv("FOO_DURATIONFROMENVVAR", "10m")
 
 	// Use command args to set config keys
 	os.Args = append(os.Args, "--nested", "ThisCameFromAnArg")