docs: add experimental-features.md

License: MIT
Signed-off-by: Lars Gierth <larsg@systemli.org>

docs/experimental-features.md

+# Experimental features of go-ipfs
+
+This document contains a list of experimental features in go-ipfs.
+These features, commands, and APIs aren't mature, and you shouldn't rely on them.
+Once they reach maturity, there's going to be mention in the changelog and release posts.
+If they don't reach maturity, the same applies, and their code is removed.
+
+Subscribe to https://github.com/ipfs/go-ipfs/issues/3397 to get updates.
+
+When you add a new experimental feature to go-ipfs, or change an experimental feature,
+you MUST please make a PR updating this document, and link the PR in the above issue.
+
+- [ipfs pubsub](#ipfs-pubsub)
+- [Client mode DHT routing](#client-mode-dht-routing)
+- [go-multiplex stream muxer](#go-multiplex-stream-muxer)
+- [Raw leaves for unixfs files](#raw-leaves-for-unixfs-files)
+- [ipfs filestore](#ipfs-filestore)
+- [Private Networks](#private-networks)
+- [ipfs p2p](#ipfs-p2p)
+
+---
+
+## ipfs pubsub
+
+### State
+
+experimental, default-disabled.
+
+### In Version
+
+0.4.5
+
+### How to enable
+
+run your daemon with the `--enable-pubsub-experiment` flag. Then use the `ipfs pubsub` commands.
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works
+- [ ] Needs authenticated modes to be implemented
+- [ ] needs performance analyses to be done
+
+---
+
+## Client mode DHT routing
+Allows the dht to be run in a mode that doesnt serve requests to the network, saving bandwidth.
+
+### State
+experimental.
+
+### In Version
+0.4.5
+
+### How to enable
+run your daemon with the `--routing=dhtclient` flag.
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works.
+- [ ] Needs analysis of effect it has on the network as a whole.
+
+---
+
+## go-multiplex stream muxer
+Adds support for using the go-multiplex stream muxer alongside (or instead of) yamux and spdy. This multiplexer is far simpler, and uses less memory and bandwidth than the others, but is lacking on congestion control and backpressure logic. It is available to try out and experiment with.
+
+### State
+Experimental
+
+### In Version
+0.4.5
+
+### How to enable
+run your daemon with `--enable-mplex-experiment`
+
+To make it the default stream muxer, set the environment variable `LIBP2P_MUX_PREFS` as follows:
+```
+export LIBP2P_MUX_PREFS="/mplex/6.7.0 /yamux/1.0.0 /spdy/3.1.0"
+```
+
+To check which stream muxer is being used between any two given peers, check the json output of the `ipfs swarm peers` command, you'll see something like this:
+```
+$ ipfs swarm peers -v --enc=json | jq .
+{
+  "Peers": [
+    {
+      "Addr": "/ip4/104.131.131.82/tcp/4001",
+      "Peer": "QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ",
+      "Latency": "46.032624ms",
+      "Muxer": "*peerstream_multiplex.conn",
+      "Streams": [
+        {
+          "Protocol": "/ipfs/bitswap/1.1.0"
+        },
+        {
+          "Protocol": "/ipfs/kad/1.0.0"
+        },
+        {
+          "Protocol": "/ipfs/kad/1.0.0"
+        }
+      ]
+    },
+    {
+...
+```
+
+### Road to being a real feature
+- [ ] Significant real world testing and performance metrics across a wide variety of workloads showing that it works well.
+
+---
+
+## Raw Leaves for unixfs files
+Allows files to be added with no formatting in the leaf nodes of the graph.
+
+### State
+experimental.
+
+### In Version
+master, 0.4.5
+
+### How to enable
+Use `--raw-leaves` flag when calling `ipfs add`.
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works.
+
+---
+
+## ipfs filestore
+Allows files to be added without duplicating the space they take up on disk.
+
+### State
+experimental.
+
+### In Version
+master, 0.4.7
+
+### How to enable
+Modify your ipfs config:
+```
+ipfs config --json Experimental.FilestoreEnabled true
+```
+
+And then pass the `--nocopy` flag when running `ipfs add`
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works.
+- [ ] Need to address error states and failure conditions
+- [ ] Need to write docs on usage, advantages, disadvantages
+- [ ] Need to merge utility commands to aid in maintenance and repair of filestore
+
+---
+
+## Private Networks
+
+Allows ipfs to only connect to other peers who have a shared secret key.
+
+### State
+Experimental
+
+### In Version
+master, 0.4.7
+
+### How to enable
+Generate a pre-shared-key using [ipfs-swarm-key-gen](https://github.com/Kubuxu/go-ipfs-swarm-key-gen)):
+```
+go get github.com/Kubuxu/go-ipfs-swarm-key-gen/ipfs-swarm-key-gen
+ipfs-swarm-key-gen > ~/.ipfs/swarm.key
+```
+
+To join a given private network, get the key file from someone in the network and save it to `~/.ipfs/swarm.key` (If you are using a custom `$IPFS_PATH`, put it in there instead).
+
+When using this feature, you will not be able to connect to the default bootstrap nodes (Since we arent part of your private network) so you will need to set up your own bootstrap nodes.
+
+To prevent your node from even trying to connect to the default bootstrap nodes, run:
+```bash
+ipfs bootstrap rm --all
+```
+
+To be extra cautious, You can also set the `LIBP2P_FORCE_PNET` environment variable to `1` to force the usage of private networks. If no private network is configured, the daemon will fail to start.
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works
+- [ ] More documentation
+
+---
+
+## ipfs p2p
+Allows to tunnel TCP connections through Libp2p sterams
+
+### State
+Experimental
+
+### In Version
+master, 0.4.10
+
+### How to enable
+P2P command needs to be enabled in config
+
+`ipfs config --json Experimental.Libp2pStreamMounting true`
+
+### How to use
+
+Basic usage:
+
+- Open a listener on one node (node A)
+`p2p listener open p2p-test /ip4/127.0.0.1/tcp/10101`
+- Connect your app to the endpoint opened locally (tcp on localhost port 10101)
+- On the other node, connect to the listener on node A
+`ipfsi 1 p2p stream dial $NODE_A_PEERID p2p-test /ip4/127.0.0.1/tcp/10102`
+- Now connect the application on node B to its tcp endpoint, and they should now be communicating
+
+### Road to being a real feature
+- [ ] Needs more people to use and report on how well it works / fits use cases
+- [ ] More documentation
+- [ ] Support other protocols