feat: support yaml evaluator (#206)

Signed-off-by: Suraj Banakar <surajrbanakar@gmail.com>

cmd/start.go

@@ -37,15 +37,17 @@ func init() {
 	flags.StringP(socketPathFlagName, "d", "", "Flagd socket path. "+
 		"With grpc the service will become available on this address. "+
 		"With http(s) the grpc-gateway proxy will use this address internally.")
-	flags.StringP(evaluatorFlagName, "e", "json", "Set an evaluator e.g. json")
+	flags.StringP(evaluatorFlagName, "e", "json", "Set an evaluator e.g. json, yaml/yml."+
+		"Please note that yaml/yml and json evaluations work the same (yaml/yml files are converted to json internally)")
 	flags.StringP(serverCertPathFlagName, "c", "", "Server side tls certificate path")
 	flags.StringP(serverKeyPathFlagName, "k", "", "Server side tls key path")
 	flags.StringToStringP(providerArgsFlagName,
 		"a", nil, "Sync provider arguments as key values separated by =")
 	flags.StringSliceP(
 		uriFlagName, "f", []string{}, "Set a sync provider uri to read data from, this can be a filepath,"+
 			"url or FeatureFlagConfiguration. Using multiple providers is supported however if"+
-			"flag keys are duplicated across multiple sources it may lead to unexpected behavior ",
+			" flag keys are duplicated across multiple sources it may lead to unexpected behavior. "+
+			"Please note that if you are using filepath, flagd only supports files with `.yaml/.yml/.json` extension.",
 	)
 	flags.StringP(
 		bearerTokenFlagName, "b", "", "Set a bearer token to use for remote sync")

config/samples/example_flags.yaml

@@ -0,0 +1,88 @@
+flags:
+  myBoolFlag:
+    state: ENABLED
+    variants:
+      'on': true
+      'off': false
+    defaultVariant: 'on'
+  myStringFlag:
+    state: ENABLED
+    variants:
+      key1: val1
+      key2: val2
+    defaultVariant: key1
+  myFloatFlag:
+    state: ENABLED
+    variants:
+      one: 1.23
+      two: 2.34
+    defaultVariant: one
+  myIntFlag:
+    state: ENABLED
+    variants:
+      one: 1
+      two: 2
+    defaultVariant: one
+  myObjectFlag:
+    state: ENABLED
+    variants:
+      object1:
+        key: val
+      object2:
+        key: true
+    defaultVariant: object1
+  isColorYellow:
+    state: ENABLED
+    variants:
+      'on': true
+      'off': false
+    defaultVariant: 'off'
+    targeting:
+      if:
+      - "==":
+        - var:
+          - color
+        - yellow
+      - 'on'
+      - 'off'
+  fibAlgo:
+    variants:
+      recursive: recursive
+      memo: memo
+      loop: loop
+      binet: binet
+    defaultVariant: recursive
+    state: ENABLED
+    targeting:
+      if:
+      - "$ref": emailWithFaas
+      - binet
+      - null
+  headerColor:
+    variants:
+      red: "#FF0000"
+      blue: "#0000FF"
+      green: "#00FF00"
+      yellow: "#FFFF00"
+    defaultVariant: red
+    state: ENABLED
+    targeting:
+      if:
+      - "$ref": emailWithFaas
+      - fractionalEvaluation:
+        - email
+        - - red
+          - 25
+        - - blue
+          - 25
+        - - green
+          - 25
+        - - yellow
+          - 25
+      - null
+"$evaluators":
+  emailWithFaas:
+    in:
+    - "@faas.com"
+    - var:
+      - email

docs/configuration/configuration.md

@@ -6,17 +6,18 @@ highest priority, followed by environment variables and finally config file.
 Supported flags are as follows (result of running `./flagd start --help`):
 
 ```
-  -b, --bearer-token string       Set a bearer token to use for remote sync
-  -e, --evaluator string          Set an evaluator e.g. json (default "json")
-  -h, --help                      help for start
-  -p, --port int32                Port to listen on (default 8013)
-  -m, --metrics-port int32        Port to set up metrics listener on (default 8014)
-  -c, --server-cert-path string   Server side tls certificate path
-  -k, --server-key-path string    Server side tls key path
-  -a, --sync-provider-args        Sync provider arguments as key values separated by =
-  -d, --socket-path string        Set the flagd socket path.
-  -f, --uri strings               Set a sync provider uri to read data from this can be a filepath, url or reference to a kubernetes custom resource. Using multiple providers is supported, however if flag keys are duplicated across multiple sources it may lead to unexpected behavior.
-  -C, --cors-origin strings       Set a CORS allow origin header, setting "*" will allow all origins (by default CORS headers are not set)
+  -b, --bearer-token string                 Set a bearer token to use for remote sync
+  -C, --cors-origin strings                 CORS allowed origins, * will allow all origins
+  -e, --evaluator string                    Set an evaluator e.g. json, yaml/yml. Please note that yaml/yml and json evaluations work the same (yaml/yml files are converted to json internally) (default "json")
+  -h, --help                                help for start
+  -m, --metrics-port int32                  Port to serve metrics on (default 8014)
+  -p, --port int32                          Port to listen on (default 8013)
+  -c, --server-cert-path string             Server side tls certificate path
+  -k, --server-key-path string              Server side tls key path
+  -d, --socket-path string                  Flagd socket path. With grpc the service will become available on this address. With http(s) the grpc-gateway proxy will use this address internally.
+  -y, --sync-provider string                DEPRECATED: Set a sync provider e.g. filepath or remote
+  -a, --sync-provider-args stringToString   Sync provider arguments as key values separated by = (default [])
+  -f, --uri .yaml/.yml/.json                Set a sync provider uri to read data from, this can be a filepath,url or FeatureFlagConfiguration. Using multiple providers is supported however if flag keys are duplicated across multiple sources it may lead to unexpected behavior. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
 ```
 
 Environment variable keys are uppercased, prefixed with `FLAGD_` and all `-` are replaced with `_`. For example,

go.mod

@@ -30,6 +30,7 @@ require (
 	golang.org/x/sync v0.0.0-20220929204114-8fcdb60fdcc0
 	google.golang.org/grpc v1.50.1
 	google.golang.org/protobuf v1.28.1
+	gopkg.in/yaml.v3 v3.0.1
 	k8s.io/api v0.25.4
 	k8s.io/apimachinery v0.25.4
 	k8s.io/client-go v0.25.4
@@ -97,7 +98,6 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/apiextensions-apiserver v0.25.4 // indirect
 	k8s.io/component-base v0.25.4 // indirect
 	k8s.io/klog/v2 v2.80.1 // indirect

pkg/runtime/from_config.go

@@ -62,7 +62,7 @@ func (r *Runtime) setService(logger *logger.Logger) {
 
 func (r *Runtime) setEvaluatorFromConfig(logger *logger.Logger) error {
 	switch r.config.Evaluator {
-	case "json":
+	case "yaml", "yml", "json":
 		r.Evaluator = eval.NewJSONEvaluator(logger)
 	default:
 		return errors.New("no evaluator set")
@@ -84,6 +84,8 @@ func (r *Runtime) setSyncImplFromConfig(logger *logger.Logger) error {
 					zap.String("sync", "filepath"),
 				),
 				ProviderArgs: r.config.ProviderArgs,
+				// evaluator here is file type: `json`, `yaml` etc.,
+				FileType: r.config.Evaluator,
 			})
 			rtLogger.Debug(fmt.Sprintf("Using filepath sync-provider for %q", uri))
 		case regCrd.Match(uriB):

pkg/sync/filepath_sync.go

@@ -2,10 +2,13 @@ package sync
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 
+	"gopkg.in/yaml.v3"
+
 	"github.com/fsnotify/fsnotify"
 	"github.com/open-feature/flagd/pkg/logger"
 )
@@ -14,6 +17,8 @@ type FilePathSync struct {
 	URI          string
 	Logger       *logger.Logger
 	ProviderArgs ProviderArgs
+	// FileType indicates the file type e.g., json, yaml/yml etc.,
+	FileType string
 }
 
 func (fs *FilePathSync) Source() string {
@@ -28,7 +33,15 @@ func (fs *FilePathSync) Fetch(_ context.Context) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return string(rawFile), nil
+
+	switch fs.FileType {
+	case "yaml", "yml":
+		return yamlToJSON(rawFile)
+	case "json":
+		return string(rawFile), nil
+	default:
+		return "", fmt.Errorf("filepath extension '%v' is not supported", fs.FileType)
+	}
 }
 
 func (fs *FilePathSync) Notify(ctx context.Context, w chan<- INotify) {
@@ -90,3 +103,22 @@ func (fs *FilePathSync) Notify(ctx context.Context, w chan<- INotify) {
 	w <- &Notifier{Event: Event[DefaultEventType]{DefaultEventTypeReady}} // signal readiness to the caller
 	<-ctx.Done()
 }
+
+// yamlToJSON is a generic helper function to convert
+// yaml to json
+func yamlToJSON(rawFile []byte) (string, error) {
+	var ms map[string]interface{}
+	// yaml.Unmarshal unmarshals to map[interface]interface{}
+	if err := yaml.Unmarshal(rawFile, &ms); err != nil {
+		return "", fmt.Errorf("unmarshal yaml: %w", err)
+	}
+
+	// Adding spaces here because our evaluator transposer function
+	// doesn't understand json without indentations quite well
+	r, err := json.MarshalIndent(ms, "", "  ")
+	if err != nil {
+		return "", fmt.Errorf("convert yaml to json: %w", err)
+	}
+
+	return string(r), err
+}

pkg/sync/filepath_sync_test.go

@@ -117,8 +117,9 @@ func TestFilePathSync_Fetch(t *testing.T) {
 	}{
 		"success": {
 			fpSync: sync.FilePathSync{
-				URI:    fmt.Sprintf("%s/%s", dirName, fetchFileName),
-				Logger: logger.NewLogger(nil, false),
+				URI:      fmt.Sprintf("%s/%s", dirName, fetchFileName),
+				Logger:   logger.NewLogger(nil, false),
+				FileType: "json", // this is the default
 			},
 			handleResponse: func(t *testing.T, fetched string, err error) {
 				if err != nil {
@@ -132,8 +133,9 @@ func TestFilePathSync_Fetch(t *testing.T) {
 		},
 		"not found": {
 			fpSync: sync.FilePathSync{
-				URI:    fmt.Sprintf("%s/%s", dirName, "not_found"),
-				Logger: logger.NewLogger(nil, false),
+				URI:      fmt.Sprintf("%s/%s", dirName, "not_found"),
+				Logger:   logger.NewLogger(nil, false),
+				FileType: "json",
 			},
 			handleResponse: func(t *testing.T, fetched string, err error) {
 				if err == nil {