fix: add validation for s3.bucket_lookup_type

Author: wuhuizuo

README.md

@@ -264,7 +264,7 @@ OPTIONS:
       [$BAZEL_REMOTE_S3_BUCKET]
 
    --s3.bucket_lookup_type value The S3/minio bucket lookup type to use when
-      using S3 proxy backend.  (default: auto, types: auto|dns|path)
+      using S3 proxy backend.  (default: auto, Allowed values: auto, dns, path.)
       [$BAZEL_REMOTE_S3_BUCKET_LOOKUP_TYPE]
 
    --s3.prefix value The S3/minio object prefix to use when using S3 proxy
@@ -466,6 +466,7 @@ http_address: 0.0.0.0:8080
 #  bucket: test-bucket
 #  prefix: test-prefix
 #  disable_ssl: true
+#  bucket_lookup_type: auto
 #
 # Provide exactly one auth_method (access_key, iam_role, or credentials_file) and accompanying configuration.
 #

config/config.go

@@ -19,6 +19,7 @@ import (
 	"github.com/buchgr/bazel-remote/v2/cache/s3proxy"
 
 	"github.com/urfave/cli/v2"
+	"golang.org/x/exp/slices"
 	yaml "gopkg.in/yaml.v3"
 )
 
@@ -349,6 +350,11 @@ func validateConfig(c *Config) error {
 		if c.S3CloudStorage.KeyVersion != nil && *c.S3CloudStorage.KeyVersion != 2 {
 			return fmt.Errorf("s3.key_version (deprecated) must be 2, found %d", c.S3CloudStorage.KeyVersion)
 		}
+
+		if c.S3CloudStorage.BucketLookupType != "" && !slices.Contains([]string{"auto", "dns", "path"}, c.S3CloudStorage.BucketLookupType) {
+			return fmt.Errorf("s3.bucket_lookup_type must be one of: [auto,dns,path] or be empty, found %s",
+				c.S3CloudStorage.BucketLookupType)
+		}
 	}
 
 	if c.AzBlobConfig != nil {

config/proxy.go

@@ -81,7 +81,7 @@ func (c *Config) setProxy() error {
 	return nil
 }
 
-func parseBucketLookupType(typeStr string) minio.BucketLookupType {
+func parseBucketLookupType(typeStr string) (minio.BucketLookupType, error) {
 	valMap := map[string]minio.BucketLookupType{
 		"auto": minio.BucketLookupAuto,
 		"dns":  minio.BucketLookupDNS,

utils/flags/flags.go

@@ -222,7 +222,7 @@ func GetCliFlags() []cli.Flag {
 		&cli.StringFlag{
 			Name:    "s3.bucket_lookup_type",
 			Value:   "auto",
-			Usage:   "The S3/minio bucket lookup type(auto|dns|path) to use when using S3 proxy backend.",
+			Usage:   "The S3/minio bucket lookup type to use when using S3 proxy backend. Allowed values: auto, dns, path.",
 			EnvVars: []string{"BAZEL_REMOTE_S3_BUCKET_LOOKUP_TYPE"},
 		},
 		&cli.StringFlag{