feat: file extension detection (#257)

Signed-off-by: James Milligan <james@omnant.co.uk>

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## This PR
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- file type is detected via the file extension, it is now possible to
mix and match `json` and `yaml` files as flag configuration sources

```
start -f file:./config/samples/example_flags.yaml -f file:./config/samples/example_flags.json
```

### Related Issues
<!-- add here the GitHub issue that this PR resolves if applicable -->

#240

### Notes
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### Follow-up Tasks
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noted under this section -->
<!-- if there is a need for a new issue, please link it here -->
It is my opinion that the `-e` or `--evaluator` flag is now a little
misleading / confusing, as only the `json_evaluator` is used internally,
and changing the flag value has no effect internally. Open to opinions
on how this should be handled, if at all.
### How to test
<!-- if applicable, add testing instructions under this section -->

Signed-off-by: James Milligan <james@omnant.co.uk>

cmd/start.go

@@ -37,7 +37,7 @@ 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, yaml/yml."+
+	flags.StringP(evaluatorFlagName, "e", "json", "DEPRECATED: 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")
@@ -95,6 +95,11 @@ var startCmd = &cobra.Command{
 				"Docs: https://github.com/open-feature/flagd/blob/main/docs/configuration.md")
 		}
 
+		if viper.GetString(evaluatorFlagName) != "" {
+			rtLogger.Warn("DEPRECATED: The --evaluator flag has been deprecated. " +
+				"Docs: https://github.com/open-feature/flagd/blob/main/docs/configuration.md")
+		}
+
 		// Build Runtime -----------------------------------------------------------
 		rt, err := runtime.FromConfig(logger, runtime.Config{
 			ServicePort:       viper.GetInt32(portFlagName),
@@ -105,7 +110,6 @@ var startCmd = &cobra.Command{
 			ProviderArgs:      viper.GetStringMapString(providerArgsFlagName),
 			SyncURI:           viper.GetStringSlice(uriFlagName),
 			SyncBearerToken:   viper.GetString(bearerTokenFlagName),
-			Evaluator:         viper.GetString(evaluatorFlagName),
 			CORS:              viper.GetStringSlice(corsFlagName),
 		})
 		if err != nil {

docs/configuration/configuration.md

@@ -8,16 +8,16 @@ Supported flags are as follows (result of running `./flagd start --help`):
 ```
   -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.
+  -e, --evaluator string                    DEPRECATED: 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")
+  -y, --sync-provider string                DEPRECATED: Set a sync provider e.g. filepath or remote
 ```
 
 Environment variable keys are uppercased, prefixed with `FLAGD_` and all `-` are replaced with `_`. For example,

pkg/runtime/from_config.go

@@ -1,7 +1,6 @@
 package runtime
 
 import (
-	"errors"
 	"fmt"
 	"net/http"
 	"regexp"
@@ -33,9 +32,7 @@ func FromConfig(logger *logger.Logger, config Config) (*Runtime, error) {
 		config:       config,
 		Logger:       logger.WithFields(zap.String("component", "runtime")),
 		syncNotifier: make(chan sync.INotify),
-	}
-	if err := rt.setEvaluatorFromConfig(logger); err != nil {
-		return nil, err
+		Evaluator:    eval.NewJSONEvaluator(logger),
 	}
 	if err := rt.setSyncImplFromConfig(logger); err != nil {
 		return nil, err
@@ -60,17 +57,6 @@ func (r *Runtime) setService(logger *logger.Logger) {
 	}
 }
 
-func (r *Runtime) setEvaluatorFromConfig(logger *logger.Logger) error {
-	switch r.config.Evaluator {
-	case "yaml", "yml", "json":
-		r.Evaluator = eval.NewJSONEvaluator(logger)
-	default:
-		return errors.New("no evaluator set")
-	}
-	logger.Debug(fmt.Sprintf("Using %s evaluator", r.config.Evaluator))
-	return nil
-}
-
 func (r *Runtime) setSyncImplFromConfig(logger *logger.Logger) error {
 	rtLogger := logger.WithFields(zap.String("component", "runtime"))
 	r.SyncImpl = make([]sync.ISync, 0, len(r.config.SyncURI))
@@ -84,8 +70,6 @@ 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/runtime/runtime.go

@@ -33,8 +33,7 @@ type Config struct {
 	SyncURI         []string
 	SyncBearerToken string
 
-	Evaluator string
-	CORS      []string
+	CORS []string
 }
 
 func (r *Runtime) startSyncer(ctx context.Context, syncr sync.ISync) error {

pkg/sync/filepath_sync.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"strings"
 
 	"gopkg.in/yaml.v3"
 
@@ -18,7 +19,7 @@ type FilePathSync struct {
 	Logger       *logger.Logger
 	ProviderArgs ProviderArgs
 	// FileType indicates the file type e.g., json, yaml/yml etc.,
-	FileType string
+	fileType string
 }
 
 func (fs *FilePathSync) Source() string {
@@ -29,18 +30,22 @@ func (fs *FilePathSync) Fetch(_ context.Context) (string, error) {
 	if fs.URI == "" {
 		return "", errors.New("no filepath string set")
 	}
+	if fs.fileType == "" {
+		uriSplit := strings.Split(fs.URI, ".")
+		fs.fileType = uriSplit[len(uriSplit)-1]
+	}
 	rawFile, err := os.ReadFile(fs.URI)
 	if err != nil {
 		return "", err
 	}
 
-	switch fs.FileType {
+	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)
+		return "", fmt.Errorf("filepath extension for URI '%s' is not supported", fs.URI)
 	}
 }
 

pkg/sync/filepath_sync_test.go

@@ -14,10 +14,10 @@ import (
 
 const (
 	dirName           = "test"
-	createFileName    = "to_create"
-	modifyFileName    = "to_modify"
-	deleteFileName    = "to_delete"
-	fetchFileName     = "to_fetch"
+	createFileName    = "to_create.json"
+	modifyFileName    = "to_modify.json"
+	deleteFileName    = "to_delete.json"
+	fetchFileName     = "to_fetch.json"
 	fetchFileContents = "fetch me"
 )
 
@@ -117,9 +117,8 @@ func TestFilePathSync_Fetch(t *testing.T) {
 	}{
 		"success": {
 			fpSync: sync.FilePathSync{
-				URI:      fmt.Sprintf("%s/%s", dirName, fetchFileName),
-				Logger:   logger.NewLogger(nil, false),
-				FileType: "json", // this is the default
+				URI:    fmt.Sprintf("%s/%s", dirName, fetchFileName),
+				Logger: logger.NewLogger(nil, false),
 			},
 			handleResponse: func(t *testing.T, fetched string, err error) {
 				if err != nil {
@@ -133,9 +132,8 @@ func TestFilePathSync_Fetch(t *testing.T) {
 		},
 		"not found": {
 			fpSync: sync.FilePathSync{
-				URI:      fmt.Sprintf("%s/%s", dirName, "not_found"),
-				Logger:   logger.NewLogger(nil, false),
-				FileType: "json",
+				URI:    fmt.Sprintf("%s/%s", dirName, "not_found"),
+				Logger: logger.NewLogger(nil, false),
 			},
 			handleResponse: func(t *testing.T, fetched string, err error) {
 				if err == nil {