feat: set failover to default false. Update readme (#82)

README.md

@@ -32,10 +32,13 @@ Traffic splitting provides a mechanism to precisely control how traffic is distr
 
 Traffic splitting configuration is managed through the `client-behavior-params` ConfigMap in the Bolt (Crunch) Kubernetes cluster. This ConfigMap can be edited on your behalf by the Granica team or by you via `custom.vars` or directly editing the ConfigMap (the latter option is not recommended as it can cause state drift.) For further guidance on the traffic splitting configuration, reach out to the Granica team.
 
-### Failover
+### Fallback on 404
+If sidekick can't find your object in Bolt, sidekick tries to find the object in S3. This happens transparently to the client, and it doesn't need any client retries.
 
-Sidekick automatically failovers the request to s3 if the bolt request fails. For example This is useful when the object does not exist in bolt yet.
-You can disable failover by passing a flag or setting a ENV variable:
+### Failover
+Sidekick has a failover mechanism that comes into play when there are network failures or when Bolt returns 500s
+In these situations sidekick returns a 500 to the client, that may cause the client to retry. The retry request will make sidekick request Bolt again but a different endpoint. Eventually, either client will exhaust all retries to sidekick or sidekick will exhaust all replica endpoints. When one of these happens, the request has failed
+The above failover mechanism is recommended, but can be changed. Sidekick can instead failover to S3 transparently to the Client immediately on noticing a network failure or 500 error. This can be set with either by a command line argument or environment variable
 
 ```bash
 # Using flag
@@ -46,12 +49,10 @@ go run main serve --failover=false
 
 ```bash
 # Using env variable
-export SIDEKICK_BOLTROUTER_FAILOVER=true
+export SIDEKICK_BOLTROUTER_FAILOVER=true  # Not recommended
 go run main serve
 ```
 
-In the context of traffic splitting, if S3 is tried first due to the defined traffic distribution, Sidekick will automatically failover to Bolt if the initial request to S3 returns a `404 NoSuchKey`. This guarantees that the requested object can still be retrieved from Bolt, preserving the desired traffic splitting behavior and ensuring data availability and consistency.
-
 ### Local
 
 You can run sidekick directly from the command line:

boltrouter/config.go

@@ -18,7 +18,7 @@ type Config struct {
 	// Enable pass through in Bolt.
 	Passthrough bool `yaml:"Passthrough"`
 
-	// Enable failover to a AWS request if the Bolt request fails or vice-versa.
+	// Enable failover to a AWS request if the Bolt request fails
 	Failover bool `yaml:"Failover"`
 
 	// Enable NoFallback404 to disable fallback on 404 response code from AWS request to Bolt or vice-versa.
@@ -35,7 +35,7 @@ type Config struct {
 var DefaultConfig = Config{
 	Local:                false,
 	Passthrough:          false,
-	Failover:             true,
+	Failover:             false,
 	NoFallback404:        false,
 	BoltEndpointOverride: "",
 	CrunchTrafficSplit:   CrunchTrafficSplitByObjectKeyHash,

cmd/serve.go

@@ -26,7 +26,7 @@ func initServerFlags(cmd *cobra.Command) {
 	cmd.Flags().BoolP("local", "l", false, "Run sidekick in local (non cloud) mode. This is mostly use for testing locally.")
 	cmd.Flags().String("bolt-endpoint-override", "", "Specify the local bolt endpoint with port to override in local mode. e.g: <local-bolt-ip>:9000")
 	cmd.Flags().Bool("passthrough", false, "Set passthrough flag to bolt requests.")
-	cmd.Flags().BoolP("failover", "f", true, "Enables aws request failover if bolt request fails.")
+	cmd.Flags().BoolP("failover", "f", false, "Enables aws request failover if bolt request fails.")
 	cmd.Flags().String("crunch-traffic-split", "objectkeyhash", "Specify the crunch traffic split strategy: random or objectkeyhash")
 }
 

cmd/serve_test.go

@@ -28,7 +28,7 @@ func TestServeCmdConfig(t *testing.T) {
 		cfg := getBoltRouterConfig(testServeCmd)
 		assert.Equal(t, false, cfg.Local)
 		assert.Equal(t, false, cfg.Passthrough)
-		assert.Equal(t, true, cfg.Failover)
+		assert.Equal(t, false, cfg.Failover)
 	})
 
 	t.Run("EnvOnly", func(t *testing.T) {