From 73fad7c9db5dfff8488e79121ec4386887765daa Mon Sep 17 00:00:00 2001
From: Albert Vaca <albertvaka@gmail.com>
Date: Tue, 26 Mar 2019 15:14:00 +0100
Subject: [PATCH 1/3] Enable storing a set of known valid config keys

This can be used to enforce a config schema
---
 viper.go | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/viper.go b/viper.go
index b098dc8..6141bed 100644
--- a/viper.go
+++ b/viper.go
@@ -196,6 +196,7 @@ type Viper struct {
 	pflags         map[string]FlagValue
 	env            map[string]string
 	aliases        map[string]string
+	knownKeys      map[string]interface{}
 	typeByDefValue bool
 
 	// Store read properties on the object so that we can write back in order with comments.
@@ -218,6 +219,7 @@ func New() *Viper {
 	v.pflags = make(map[string]FlagValue)
 	v.env = make(map[string]string)
 	v.aliases = make(map[string]string)
+	v.knownKeys = make(map[string]interface{})
 	v.typeByDefValue = false
 
 	return v
@@ -1036,6 +1038,8 @@ func (v *Viper) BindEnv(input ...string) error {
 
 	v.env[key] = envkey
 
+	v.SetKnown(key)
+
 	return nil
 }
 
@@ -1233,6 +1237,7 @@ func (v *Viper) registerAlias(alias string, key string) {
 	} else {
 		jww.WARN.Println("Creating circular reference alias", alias, key, v.realKey(key))
 	}
+	v.SetKnown(alias)
 }
 
 func (v *Viper) realKey(key string) string {
@@ -1269,6 +1274,27 @@ func (v *Viper) SetDefault(key string, value interface{}) {
 
 	// set innermost value
 	deepestMap[lastKey] = value
+	v.SetKnown(key)
+}
+
+// SetKnown adds a key to the set of known valid config keys
+func (v *Viper) SetKnown(key string) {
+	key = strings.ToLower(key)
+	splitPath := strings.Split(key, v.keyDelim)
+	for j := range splitPath {
+		subKey := strings.Join(splitPath[:j+1], v.keyDelim)
+		v.knownKeys[subKey] = struct{}{}
+	}
+}
+
+// GetKnownKeys returns all the keys that meet at least one of these criteria:
+// 1) have a default, 2) have an environment variable binded, 3) are an alias or 4) have been SetKnown()
+func (v *Viper) GetKnownKeys() map[string]interface{} {
+	ret := make(map[string]interface{})
+	for key, value := range v.knownKeys {
+		ret[key] = value
+	}
+	return ret
 }
 
 // Set sets the value for the key in the override register.

From ead7a65a23c21eb6ed5c5fe29e0d5471b4667db4 Mon Sep 17 00:00:00 2001
From: Albert Vaca <albert.vaca@datadoghq.com>
Date: Tue, 23 Apr 2019 12:40:19 +0200
Subject: [PATCH 2/3] Added missing global versions of SetKnown/GetKnown

For consistency
---
 viper.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/viper.go b/viper.go
index 6141bed..21a9a2e 100644
--- a/viper.go
+++ b/viper.go
@@ -1278,6 +1278,7 @@ func (v *Viper) SetDefault(key string, value interface{}) {
 }
 
 // SetKnown adds a key to the set of known valid config keys
+func SetKnown(key string) { v.SetKnown(key) }
 func (v *Viper) SetKnown(key string) {
 	key = strings.ToLower(key)
 	splitPath := strings.Split(key, v.keyDelim)
@@ -1289,6 +1290,7 @@ func (v *Viper) SetKnown(key string) {
 
 // GetKnownKeys returns all the keys that meet at least one of these criteria:
 // 1) have a default, 2) have an environment variable binded, 3) are an alias or 4) have been SetKnown()
+func GetKnownKeys() map[string]interface{} { return v.GetKnownKeys() }
 func (v *Viper) GetKnownKeys() map[string]interface{} {
 	ret := make(map[string]interface{})
 	for key, value := range v.knownKeys {

From e8b327076752f8d9a164208aee987b84ebb1cf99 Mon Sep 17 00:00:00 2001
From: Albert Vaca <albert.vaca@datadoghq.com>
Date: Tue, 23 Apr 2019 12:40:40 +0200
Subject: [PATCH 3/3] Added test for known keys

---
 viper_test.go | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/viper_test.go b/viper_test.go
index d5296df..fd6a703 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -1739,3 +1739,23 @@ func BenchmarkGetBoolFromMap(b *testing.B) {
 		}
 	}
 }
+
+func TestKnownKeys(t *testing.T) {
+	v := New()
+	v.SetDefault("default", 45)
+	if _, ok := v.GetKnownKeys()["default"]; !ok {
+		t.Error("SetDefault didn't mark key as known")
+	}
+	v.BindEnv("bind", "my_env_var")
+	if _, ok := v.GetKnownKeys()["bind"]; !ok {
+		t.Error("BindEnv didn't mark key as known")
+	}
+	v.RegisterAlias("my_alias", "key")
+	if _, ok := v.GetKnownKeys()["my_alias"]; !ok {
+		t.Error("RegisterAlias didn't mark alias as known")
+	}
+	v.SetKnown("known")
+	if _, ok := v.GetKnownKeys()["known"]; !ok {
+		t.Error("SetKnown didn't mark key as known")
+	}
+}