feat(flags): Add method for fetching decrypted remote config flag payload (#84)

* feat(flags): Add method for fetching decrypted remote config flag payload

* fix tests

* fix broken test

* Address comment around user agent header

* tweak

* bump minor version

* Use flag key instead of id

* Add json examples

* address comment

* Clean up method name

Author: havenbarnes

config.go

@@ -92,6 +92,8 @@ type Config struct {
 	maxConcurrentRequests int
 }
 
+const SdkName = "posthog-go"
+
 // This constant sets the default endpoint to which client instances send
 // messages if none was explictly set.
 const DefaultEndpoint = "https://app.posthog.com"

examples/featureflags.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"time"
 
@@ -12,7 +13,7 @@ func TestIsFeatureEnabled() {
 		Interval:                           30 * time.Second,
 		BatchSize:                          100,
 		Verbose:                            true,
-		PersonalApiKey:                     "phx_n79cT52OfsxAWDhZs9j3w67aRoBCZ7l5ksRRKmAi5nr",
+		PersonalApiKey:                     "phx_DvugINPCOSM3Ko929TaeywnUlRC5FeF4X7KV60IgyXWGTLw",
 		Endpoint:                           "http://localhost:8000",
 		DefaultFeatureFlagsPollingInterval: 5 * time.Second,
 		FeatureFlagRequestTimeout:          3 * time.Second,
@@ -61,4 +62,21 @@ func TestIsFeatureEnabled() {
 	if variantErr != nil || variantResult == true {
 		fmt.Println("error:", variantErr)
 	}
+
+	// Encrypted remote config flag (string payload)
+	stringPayloadResult, stringPayloadErr := client.GetRemoteConfigPayload("my_secret_flag_value")
+	fmt.Println("stringPayloadResult:", stringPayloadResult)
+	if stringPayloadErr != nil {
+		fmt.Println("error:", stringPayloadErr)
+	}
+
+	// Encrypted remote config flag (json object payload)
+	jsonObjectPayloadResult, _ := client.GetRemoteConfigPayload("my_secret_flag_json_object_value")
+	var jsonPayloadMap map[string]interface{}
+	json.Unmarshal([]byte(jsonObjectPayloadResult), &jsonPayloadMap)
+
+	// Encrypted remote config flag (json array payload)
+	jsonArrayPayloadResult, _ := client.GetRemoteConfigPayload("my_secret_flag_json_array_value")
+	var jsonArrayPayload []string
+	json.Unmarshal([]byte(jsonArrayPayloadResult), &jsonArrayPayload)
 }

feature_flags_test.go

@@ -945,6 +945,33 @@ func TestGetFeatureFlagPayload(t *testing.T) {
 	}
 }
 
+func TestGetRemoteConfigPayload(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write([]byte(fixture("test-remote-config.json")))
+	}))
+
+	defer server.Close()
+
+	client, _ := NewWithConfig("Csyjlnlun3OzyNJAafdlv", Config{
+		PersonalApiKey: "some very secret key",
+		Endpoint:       server.URL,
+	})
+	defer client.Close()
+
+	payload, _ := client.GetRemoteConfigPayload("flag_key")
+
+	var payloadMap map[string]interface{}
+	err := json.Unmarshal([]byte(payload), &payloadMap)
+	if err != nil {
+		t.Error("Failed to decode payload")
+	}
+
+	if payloadMap["foo"] != "bar" || payloadMap["baz"] != float64(42) {
+		t.Error("Should match")
+	}
+}
+
+
 func TestFlagWithVariantOverrides(t *testing.T) {
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

featureflags.go

@@ -900,7 +900,7 @@ func (poller *FeatureFlagsPoller) request(method string, url *url.URL, requestDa
 
 	version := getVersion()
 
-	req.Header.Add("User-Agent", "posthog-go (version: "+version+")")
+	req.Header.Add("User-Agent", SdkName+"/"+version)
 	req.Header.Add("Content-Type", "application/json")
 	req.Header.Add("Content-Length", fmt.Sprintf("%d", len(requestData)))
 

fixtures/test-remote-config.json

@@ -0,0 +1 @@
+"{\"foo\": \"bar\",\"baz\": 42}"

posthog.go

@@ -48,6 +48,9 @@ type Client interface {
 	// Method returns feature flag payload value matching key for user (supports multivariate flags).
 	GetFeatureFlagPayload(FeatureFlagPayload) (string, error)
 	//
+	// Method returns decrypted feature flag payload value for remote config flags.
+	GetRemoteConfigPayload(string) (string, error)
+	//
 	// Get all flags - returns all flags for a user
 	GetAllFlags(FeatureFlagPayloadNoKey) (map[string]interface{}, error)
 	//
@@ -358,6 +361,10 @@ func (c *client) GetFeatureFlag(flagConfig FeatureFlagPayload) (interface{}, err
 	return flagValue, err
 }
 
+func (c *client) GetRemoteConfigPayload(flagKey string) (string, error) {
+	return c.makeRemoteConfigRequest(flagKey)
+}
+
 func (c *client) GetFeatureFlags() ([]FeatureFlag, error) {
 	if c.featureFlagsPoller == nil {
 		errorMessage := "specifying a PersonalApiKey is required for using feature flags"
@@ -472,7 +479,7 @@ func (c *client) upload(b []byte) error {
 
 	version := getVersion()
 
-	req.Header.Add("User-Agent", "posthog-go (version: "+version+")")
+	req.Header.Add("User-Agent", SdkName+"/"+version)
 	req.Header.Add("Content-Type", "application/json")
 	req.Header.Add("Content-Length", fmt.Sprintf("%d", len(b)))
 
@@ -653,7 +660,7 @@ func (c *client) makeDecideRequest(distinctId string, groups Groups, personPrope
 	}
 
 	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("User-Agent", "posthog-go (version: "+Version+")")
+	req.Header.Set("User-Agent", "posthog-go/"+Version)
 
 	res, err := c.http.Do(req)
 	if err != nil {
@@ -679,6 +686,44 @@ func (c *client) makeDecideRequest(distinctId string, groups Groups, personPrope
 	return &decideResponse, nil
 }
 
+func (c *client) makeRemoteConfigRequest(flagKey string) (string, error) {
+	remoteConfigEndpoint := fmt.Sprintf("api/projects/@current/feature_flags/%s/remote_config/", flagKey)
+	url, err := url.Parse(c.Endpoint + "/" + remoteConfigEndpoint)
+	if err != nil {
+		return "", fmt.Errorf("creating url: %v", err)
+	}
+
+	req, err := http.NewRequest("GET", url.String(), nil)
+	if err != nil {
+		return "", fmt.Errorf("creating request: %v", err)
+	}
+
+	req.Header.Set("Authorization", "Bearer "+c.PersonalApiKey)
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", "posthog-go/"+Version)
+
+	res, err := c.http.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("sending request: %v", err)
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("unexpected status code from %s: %d", remoteConfigEndpoint, res.StatusCode)
+	}
+
+	resBody, err := io.ReadAll(res.Body)
+	if err != nil {
+		return "", fmt.Errorf("error reading response from /remote_config/: %v", err)
+	}
+
+	var responseData string
+	if err := json.Unmarshal(resBody, &responseData); err != nil {
+		return "", fmt.Errorf("error parsing JSON response from /remote_config/: %v", err)
+	}
+	return responseData, nil
+}
+	
 func (c *client) getFeatureFlagFromDecide(key string, distinctId string, groups Groups, personProperties Properties, groupProperties map[string]Properties) (interface{}, error) {
 	decideResponse, err := c.makeDecideRequest(distinctId, groups, personProperties, groupProperties)
 	if err != nil {

posthog_test.go

@@ -264,7 +264,6 @@ func ExampleHistoricalMigrationCapture() {
 		Endpoint:            server.URL,
 		BatchSize:           1,
 		now:                 mockTime,
-		uid:                 mockId,
 		HistoricalMigration: true,
 	})
 	defer client.Close()
@@ -299,7 +298,8 @@ func ExampleHistoricalMigrationCapture() {
 	//       },
 	//       "send_feature_flags": false,
 	//       "timestamp": "2009-11-10T23:00:00Z",
-	//       "type": "capture"
+	//       "type": "capture",
+	//       "uuid": ""
 	//     }
 	//   ],
 	//   "historical_migration": true
@@ -1100,7 +1100,7 @@ func TestGetFeatureFlagPayloadWithNoPersonalApiKey(t *testing.T) {
 				if r.Header.Get("Content-Type") != "application/json" {
 					t.Errorf("Expected Content-Type: application/json, got %s", r.Header.Get("Content-Type"))
 				}
-				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go (version: ") {
+				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go/") {
 					t.Errorf("Unexpected User-Agent: %s", r.Header.Get("User-Agent"))
 				}
 
@@ -1300,7 +1300,7 @@ func TestGetFeatureFlagWithNoPersonalApiKey(t *testing.T) {
 				if r.Header.Get("Content-Type") != "application/json" {
 					t.Errorf("Expected Content-Type: application/json, got %s", r.Header.Get("Content-Type"))
 				}
-				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go (version: ") {
+				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go/") {
 					t.Errorf("Unexpected User-Agent: %s", r.Header.Get("User-Agent"))
 				}
 
@@ -1437,7 +1437,7 @@ func TestGetAllFeatureFlagsWithNoPersonalApiKey(t *testing.T) {
 				if r.Header.Get("Content-Type") != "application/json" {
 					t.Errorf("Expected Content-Type: application/json, got %s", r.Header.Get("Content-Type"))
 				}
-				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go (version: ") {
+				if !strings.HasPrefix(r.Header.Get("User-Agent"), "posthog-go/") {
 					t.Errorf("Unexpected User-Agent: %s", r.Header.Get("User-Agent"))
 				}
 

version.go

@@ -3,7 +3,7 @@ package posthog
 import "flag"
 
 // Version of the client.
-const Version = "1.2.24"
+const Version = "1.3.0"
 
 // make tests easier by using a constant version
 func getVersion() string {