docs: remote backend configuration

docs/environment-variables.md

@@ -162,6 +162,33 @@ queries from these safelisted peers, serving locally cached blocks if requested.
 
 Default: `false` (no cache sharing)
 
+### `RAINBOW_DHT_ROUTING`
+
+Control the type of Amino DHT client used for for routing. Options are `accelerated`, `standard` and `off`.
+
+Default: `accelerated`
+
+### `RAINBOW_REMOTE_BACKENDS`
+
+> [!WARNING]
+> Experimental feature. Requires setting `RAINBOW_DHT_ROUTING=off` and  `RAINBOW_BITSWAP=false`.
+
+URL(s) of of remote [trustless gateways](https://docs.ipfs.tech/reference/http/gateway/#trustless-verifiable-retrieval)
+to use as backend instead of libp2p node with Bitswap.
+
+Default: not set
+
+### `RAINBOW_REMOTE_BACKENDS_MODE`
+
+Requires `RAINBOW_REMOTE_BACKENDS` to be set.
+
+Controls how requests to remote backend are made.
+
+- `block`  will use [application/vnd.ipld.raw](https://www.iana.org/assignments/media-types/application/vnd.ipld.raw) to fetch raw blocks one by one
+- `car` will use [application/vnd.ipld.car](https://www.iana.org/assignments/media-types/application/vnd.ipld.car) and [IPIP-402: Partial CAR Support on Trustless Gateways](https://specs.ipfs.tech/ipips/ipip-0402/) for fetching multiple blocks per request
+
+Default: `block`
+
 ## Logging
 
 ### `GOLOG_LOG_LEVEL`

main.go

@@ -228,7 +228,7 @@ Generate an identity seed and launch a gateway:
 			Name:    "peering",
 			Value:   cli.NewStringSlice(),
 			EnvVars: []string{"RAINBOW_PEERING"},
-			Usage:   "Multiaddresses of peers to stay connected to (comma-separated)",
+			Usage:   "(EXPERIMENTAL) Multiaddresses of peers to stay connected to and ask for missing blocks over Bitswap (comma-separated)",
 		},
 		&cli.BoolFlag{
 			Name:    "peering-shared-cache",
@@ -258,13 +258,13 @@ Generate an identity seed and launch a gateway:
 			Name:    "remote-backends",
 			Value:   cli.NewStringSlice(),
 			EnvVars: []string{"RAINBOW_REMOTE_BACKENDS"},
-			Usage:   "Trustless gateways to use as backend instead of Bitswap (comma-separated urls)",
+			Usage:   "(EXPERIMENTAL) Trustless gateways to use as backend instead of Bitswap (comma-separated urls)",
 		},
 		&cli.StringFlag{
 			Name:    "remote-backends-mode",
 			Value:   "block",
 			EnvVars: []string{"RAINBOW_REMOTE_BACKENDS_MODE"},
-			Usage:   "Whether to fetch raw blocks or CARs from the remote backends. Options are 'block' or 'car'",
+			Usage:   "(EXPERIMENTAL) Whether to fetch raw blocks or CARs from the remote backends. Options are 'block' or 'car'",
 			Action: func(ctx *cli.Context, s string) error {
 				switch RemoteBackendMode(s) {
 				case RemoteBackendBlock, RemoteBackendCAR:

setup.go

@@ -137,11 +137,11 @@ func SetupNoLibp2p(ctx context.Context, cfg Config, dnsCache *cachedDNS) (*Node,
 
 	// The stars aligned and Libp2p does not need to be turned on at all.
 	if len(cfg.RemoteBackends) == 0 {
-		return nil, errors.New("remote backends must be set when bitswap and dht are disabled")
+		return nil, errors.New("URL of RAINBOW_REMOTE_BACKENDS must be set when RAINBOW_BITSWAP and RAINBOW_DHT_ROUTING are disabled")
 	}
 
 	// Setup a Value Store composed of both the remote backends and the delegated
-	// routers, if they exist. This vs is only used for the namesystem.
+	// routers, if they exist. This vs is only used for resolving IPNS Records.
 	vs, err := setupRoutingNoLibp2p(cfg, dnsCache)
 	if err != nil {
 		return nil, err