feat(config): Add gateway-over-libp2p experiment

.github/workflows/gateway-conformance.yml

@@ -60,6 +60,7 @@ jobs:
         run: |
           ./ipfs init --profile=test
           ./ipfs config --json Gateway.PublicGateways "$GATEWAY_PUBLIC_GATEWAYS"
+          ./ipfs config --json Experimental.GatewayOverLibp2p true
           ./ipfs config Addresses.Gateway "/ip4/127.0.0.1/tcp/8080"
           ./ipfs config Addresses.API "/ip4/127.0.0.1/tcp/5001"
         working-directory: kubo-gateway/cmd/ipfs

cmd/ipfs/daemon.go

@@ -909,17 +909,27 @@ func serveHTTPGateway(req *cmds.Request, cctx *oldcmds.Context) (<-chan error, e
 const gatewayProtocolID protocol.ID = "/ipfs/gateway" // FIXME: specify https://github.com/ipfs/specs/issues/433
 
 func serveTrustlessGatewayOverLibp2p(cctx *oldcmds.Context) (<-chan error, error) {
+	node, err := cctx.ConstructNode()
+	if err != nil {
+		return nil, fmt.Errorf("serveHTTPGatewayOverLibp2p: ConstructNode() failed: %s", err)
+	}
+	cfg, err := node.Repo.Config()
+	if err != nil {
+		return nil, fmt.Errorf("could not read config: %w", err)
+	}
+
+	if !cfg.Experimental.GatewayOverLibp2p {
+		errCh := make(chan error)
+		close(errCh)
+		return errCh, nil
+	}
+
 	opts := []corehttp.ServeOption{
 		corehttp.MetricsCollectionOption("libp2p-gateway"),
 		corehttp.Libp2pGatewayOption(),
 		corehttp.VersionOption(),
 	}
 
-	node, err := cctx.ConstructNode()
-	if err != nil {
-		return nil, fmt.Errorf("serveHTTPGateway: ConstructNode() failed: %s", err)
-	}
-
 	handler, err := corehttp.MakeHandler(node, nil, opts...)
 	if err != nil {
 		return nil, err

config/experiments.go

@@ -11,4 +11,5 @@ type Experiments struct {
 	AcceleratedDHTClient          experimentalAcceleratedDHTClient `json:",omitempty"`
 	OptimisticProvide             bool
 	OptimisticProvideJobsPoolSize int
+	GatewayOverLibp2p             bool `json:",omitempty"`
 }

docs/experimental-features.md

@@ -27,6 +27,7 @@ the above issue.
 - [Graphsync](#graphsync)
 - [Noise](#noise)
 - [Optimistic Provide](#optimistic-provide)
+- [HTTP Gateway over Libp2p](#http-gateway-over-libp2p)
 
 ---
 
@@ -617,3 +618,39 @@ ipfs config --json Experimental.OptimisticProvideJobsPoolSize 120
 
 - [ ] Needs more people to use and report on how well it works
 - [ ] Should prove at least equivalent availability of provider records as the classic approach
+
+## HTTP Gateway over Libp2p
+
+### In Version
+
+0.23.0
+
+### State
+
+Experimental, disabled by default.
+
+Enables serving the [IPFS HTTP Gateway](https://specs.ipfs.tech/http-gateways/) protocol over libp2p transports and
+as described in the [specification](https://github.com/ipfs/specs/pull/434).
+
+Notes:
+- This feature currently is only about serving the gateway requests over libp2p, not about fetching data this way using 
+[Trustless Gateway Specification](https://specs.ipfs.tech/http-gateways/trustless-gateway/).
+- While kubo currently mounts the gateway API at the root (i.e. `/`) of the libp2p `/http/1.1` protocol that is subject to
+change. The way to reliably discover where a given HTTP protocol is mounted on a libp2p endpoint is via the `.well-known/libp2p`
+resource specified in the [http+libp2p specification](https://github.com/libp2p/specs/pull/508)
+- Kubo currently hard codes the gateway-over-libp2p behavior to:
+  - Only operate on `/ipfs` resources
+  - Only satisfy the Trustless Gateway API
+  - Only serve data that is already local to the node (i.e. similar to a `NoFetch` gateway)
+
+### How to enable
+
+Modify your ipfs config:
+
+```
+ipfs config --json Experimental.GatewayOverLibp2p true
+```
+
+### Road to being a real feature
+
+- [ ] Needs more people to use and report on how well it works

test/cli/http_gateway_over_libp2p_test.go

@@ -57,6 +57,16 @@ func TestGatewayOverLibp2p(t *testing.T) {
 	p2pProxyNodeHTTPListenAddr, err := manet.ToNetAddr(p2pProxyNodeHTTPListenMA)
 	require.NoError(t, err)
 
+	t.Run("DoesNotWorkWithoutExperimentalConfig", func(t *testing.T) {
+		_, err := http.Get(fmt.Sprintf("http://%s/ipfs/%s?format=raw", p2pProxyNodeHTTPListenAddr, cidDataOnGatewayNode))
+		require.Error(t, err)
+	})
+
+	// Enable the experimental feature and reconnect the nodes
+	gwNode.IPFS("config", "--json", "Experimental.GatewayOverLibp2p", "true")
+	gwNode.StopDaemon().StartDaemon()
+	nodes.Connect()
+
 	// Note: the bare HTTP requests here assume that the gateway is mounted at `/`
 	t.Run("WillNotServeRemoteContent", func(t *testing.T) {
 		resp, err := http.Get(fmt.Sprintf("http://%s/ipfs/%s?format=raw", p2pProxyNodeHTTPListenAddr, cidDataNotOnGatewayNode))