docs: add config file

README.md

@@ -328,7 +328,7 @@ Enable and configure experimental features.
 |------|---------|
 | object |  [`config-nodejs.js`](https://github.com/ipfs/js-ipfs/tree/master/src/core/runtime/config-nodejs.js) in Node.js, [`config-browser.js`](https://github.com/ipfs/js-ipfs/tree/master/src/core/runtime/config-browser.js) in browsers |
 
-Modify the default IPFS node config. This object will be *merged* with the default config; it will not replace it.
+Modify the default IPFS node config. This object will be *merged* with the default config; it will not replace it. The default config is documented in [the js-ipfs config file doc](config.md).
 
 ###### Configuring Delegate Routers
 

config.md

@@ -0,0 +1,164 @@
+# The js-ipfs config file
+
+The js-ipfs config file is a JSON document located in the root directory of the js-ipfs repository.
+
+## Table of Contents
+
+- [`Addresses`](#addresses)
+- [`Bootstrap`](#bootstrap)
+- [`Datastore`](#datastore)
+- [`Discovery`](#discovery)
+- [`Identity`](#identity)
+- [`Swarm`](#swarm)
+
+
+## `Addresses`
+Contains information about various listener addresses to be used by this node.
+
+- `API`
+The IPFS daemon exposes an HTTP API that allows to control the node and
+run the same commands as you can do from the command line. It is defined
+on the [HTTP API Spec](https://docs.ipfs.io/reference/api/http).
+
+Multiaddr describing the address to serve the local HTTP API on.
+
+Default: `/ip4/127.0.0.1/tcp/5002`
+
+- `Gateway`
+A gateway is exposed by the IPFS daemon, which allows an easy way to
+access content from IPFS, using an IPFS path.
+
+Multiaddr describing the address to serve the local gateway on.
+
+Default: `/ip4/127.0.0.1/tcp/9090`
+
+- `Swarm`
+Array of multiaddrs describing which addresses to listen on for p2p swarm connections.
+
+Default:
+```json
+[
+  "/ip4/0.0.0.0/tcp/4002",
+  "/ip4/127.0.0.1/tcp/4003/ws"
+]
+```
+
+## `Bootstrap`
+Bootstrap is an array of multiaddrs of trusted nodes to connect to in order to
+initiate a connection to the network.
+
+## `Datastore`
+Contains information related to the construction and operation of the on-disk
+storage system.
+
+- `Spec`
+Spec defines the structure of the ipfs datastore. It is a composable structure, where each datastore is represented by a json object. Datastores can wrap other datastores to provide extra functionality (eg metrics, logging, or caching).
+
+This can be changed manually, however, if you make any changes that require a different on-disk structure, you will need to run the [ipfs-ds-convert tool](https://github.com/ipfs/ipfs-ds-convert) to migrate data into the new structures.
+
+For more information on possible values for this configuration option, see docs/datastores.md
+
+Default:
+```
+{
+  "mounts": [
+	{
+	  "child": {
+		"path": "blocks",
+		"shardFunc": "/repo/flatfs/shard/v1/next-to-last/2",
+		"sync": true,
+		"type": "flatfs"
+	  },
+	  "mountpoint": "/blocks",
+	  "prefix": "flatfs.datastore",
+	  "type": "measure"
+	},
+	{
+	  "child": {
+		"compression": "none",
+		"path": "datastore",
+		"type": "levelds"
+	  },
+	  "mountpoint": "/",
+	  "prefix": "leveldb.datastore",
+	  "type": "measure"
+	}
+  ],
+  "type": "mount"
+}
+```
+
+## `Discovery`
+Contains options for configuring ipfs node discovery mechanisms.
+
+- `MDNS`
+Multicast dns is a discovery protocol that is able to find other peers
+on the local network.
+
+Options for multicast dns peer discovery.
+
+  - `Enabled`
+A boolean value for whether or not mdns should be active.
+
+Default: `true`
+
+  -  `Interval`
+A number of seconds to wait between discovery checks.
+
+Default: `10`
+
+- `webRTCStar`
+WebRTCStar is a discovery mechanism prvided by a signalling-star that allows peer-to-peer communications in the browser.  
+
+Options for webRTCstar peer discovery.
+
+  - `Enabled`
+A boolean value for whether or not webRTCStar should be active.
+
+Default: `true`
+
+## `Identity`
+
+- `PeerID`
+The unique PKI identity label for this configs peer. Set on init and never read,
+its merely here for convenience. IPFS will always generate the peerID from its
+keypair at runtime.
+
+- `PrivKey`
+The base64 encoded protobuf describing (and containing) the nodes private key.
+
+## `Swarm`
+
+Options for configuring the swarm.
+
+### `ConnMgr`
+
+The connection manager determines which and how many connections to keep and can be configured to keep.
+
+#### Basic Connection Manager
+
+- `LowWater`
+LowWater is the minimum number of connections to maintain.
+
+- `HighWater`
+HighWater is the number of connections that, when exceeded, will trigger a connection GC operation.
+
+
+The "basic" connection manager tries to keep between `LowWater` and `HighWater` connections. It works by:
+
+1. Keeping all connections until `HighWater` connections is reached.
+2. Once `HighWater` is reached, it closes connections until `LowWater` is reached.
+
+**Example:**
+
+
+```json
+{
+  "Swarm": {
+    "ConnMgr": {
+      "LowWater": 100,
+      "HighWater": 200,
+    }
+  }
+}
+```