refactor(config): remove Swarm.ConnMgr defaults

This moves defaults to Kubo code, cleaning up config.
If value is in config, we assume it is an explicit choice made by user.
Makes migrations easier.

config/init.go

@@ -79,14 +79,6 @@ func InitWithIdentity(identity Identity) (*Config, error) {
 			Interval: "12h",
 			Strategy: "all",
 		},
-		Swarm: SwarmConfig{
-			ConnMgr: ConnMgr{
-				LowWater:    DefaultConnMgrLowWater,
-				HighWater:   DefaultConnMgrHighWater,
-				GracePeriod: DefaultConnMgrGracePeriod.String(),
-				Type:        "basic",
-			},
-		},
 		Pinning: Pinning{
 			RemoteServices: map[string]RemotePinningService{},
 		},
@@ -114,6 +106,10 @@ const DefaultConnMgrLowWater = 600
 // grace period
 const DefaultConnMgrGracePeriod = time.Second * 20
 
+// DefaultConnMgrType is the default value for the connection managers
+// type.
+const DefaultConnMgrType = "basic"
+
 func addressesConfig() Addresses {
 	return Addresses{
 		Swarm: []string{

config/profile.go

@@ -178,9 +178,13 @@ fetching may be degraded.
 			c.AutoNAT.ServiceMode = AutoNATServiceDisabled
 			c.Reprovider.Interval = "0"
 
-			c.Swarm.ConnMgr.LowWater = 20
-			c.Swarm.ConnMgr.HighWater = 40
-			c.Swarm.ConnMgr.GracePeriod = time.Minute.String()
+			lowWater := int64(20)
+			highWater := int64(40)
+			gracePeriod := time.Minute
+			c.Swarm.ConnMgr.Type = NewOptionalString("basic")
+			c.Swarm.ConnMgr.LowWater = &OptionalInteger{value: &lowWater}
+			c.Swarm.ConnMgr.HighWater = &OptionalInteger{value: &highWater}
+			c.Swarm.ConnMgr.GracePeriod = &OptionalDuration{&gracePeriod}
 			return nil
 		},
 	},

config/swarm.go

@@ -131,10 +131,10 @@ type Transports struct {
 
 // ConnMgr defines configuration options for the libp2p connection manager
 type ConnMgr struct {
-	Type        string
-	LowWater    int
-	HighWater   int
-	GracePeriod string
+	Type        *OptionalString   `json:",omitempty"`
+	LowWater    *OptionalInteger  `json:",omitempty"`
+	HighWater   *OptionalInteger  `json:",omitempty"`
+	GracePeriod *OptionalDuration `json:",omitempty"`
 }
 
 // ResourceMgr defines configuration options for the libp2p Network Resource Manager

core/node/groups.go

@@ -38,33 +38,20 @@ var BaseLibP2P = fx.Options(
 )
 
 func LibP2P(bcfg *BuildCfg, cfg *config.Config) fx.Option {
-	// parse ConnMgr config
-
-	grace := config.DefaultConnMgrGracePeriod
-	low := config.DefaultConnMgrLowWater
-	high := config.DefaultConnMgrHighWater
-
-	connmgr := fx.Options()
-
-	if cfg.Swarm.ConnMgr.Type != "none" {
-		switch cfg.Swarm.ConnMgr.Type {
-		case "":
-			// 'default' value is the basic connection manager
-			break
-		case "basic":
-			var err error
-			grace, err = time.ParseDuration(cfg.Swarm.ConnMgr.GracePeriod)
-			if err != nil {
-				return fx.Error(fmt.Errorf("parsing Swarm.ConnMgr.GracePeriod: %s", err))
-			}
-
-			low = cfg.Swarm.ConnMgr.LowWater
-			high = cfg.Swarm.ConnMgr.HighWater
-		default:
-			return fx.Error(fmt.Errorf("unrecognized ConnMgr.Type: %q", cfg.Swarm.ConnMgr.Type))
-		}
-
+	var connmgr fx.Option
+
+	// set connmgr based on Swarm.ConnMgr.Type
+	connMgrType := cfg.Swarm.ConnMgr.Type.WithDefault(config.DefaultConnMgrType)
+	switch connMgrType {
+	case "none":
+		connmgr = fx.Options() // noop
+	case "", "basic":
+		grace := cfg.Swarm.ConnMgr.GracePeriod.WithDefault(config.DefaultConnMgrGracePeriod)
+		low := int(cfg.Swarm.ConnMgr.LowWater.WithDefault(config.DefaultConnMgrLowWater))
+		high := int(cfg.Swarm.ConnMgr.HighWater.WithDefault(config.DefaultConnMgrHighWater))
 		connmgr = fx.Provide(libp2p.ConnectionManager(low, high, grace))
+	default:
+		return fx.Error(fmt.Errorf("unrecognized Swarm.ConnMgr.Type: %q", connMgrType))
 	}
 
 	// parse PubSub config

core/node/libp2p/rcmgr_defaults.go

@@ -197,12 +197,5 @@ func createDefaultLimitConfig(cfg config.SwarmConfig) (rcmgr.LimitConfig, error)
 
 	defaultLimitConfig := scalingLimitConfig.Scale(int64(maxMemory), int(numFD))
 
-	// If a high water mark is set:
-	if cfg.ConnMgr.Type == "basic" {
-		// set the connection limit higher than high water mark so that the ConnMgr has "space and time" to close "least useful" connections.
-		defaultLimitConfig.System.Conns = 2 * cfg.ConnMgr.HighWater
-		log.Info("adjusted default resource manager System.Conns limits to match ConnMgr.HighWater value of %s", cfg.ConnMgr.HighWater)
-	}
-
 	return defaultLimitConfig, nil
 }

docs/changelogs/v0.17.md

@@ -9,8 +9,8 @@ Below is an outline of all that is in this release, so you get a sense of all th
 - [Kubo changelog v0.17](#kubo-changelog-v017)
   - [v0.17.0](#v0170)
     - [Overview](#overview)
-    - [TOC](#toc)
     - [🔦 Highlights](#-highlights)
+      - [Implicit connection manager limits](#implicit-connection-manager-limits)
       - [TAR Response Format on Gateways](#tar-response-format-on-gateways)
     - [Changelog](#changelog)
     - [Contributors](#contributors)
@@ -19,6 +19,23 @@ Below is an outline of all that is in this release, so you get a sense of all th
 
 <!-- TODO -->
 
+#### Implicit connection manager limits
+
+Starting with this release, `ipfs init` will no longer store the default
+[Connection Manager](https://github.com/ipfs/kubo/blob/master/docs/config.md#swarmconnmgr)
+limits in the user config under `Swarm.ConnMgr`.
+
+Users are still free to use this setting to set custom values, but for most use
+cases, the defaults provided with the latest Kubo release should be sufficient.
+
+To remove any custom limits and switch to the implicit defaults managed by Kubo:
+
+```console
+$ ipfs config --json Swarm.ConnMgr '{}'
+```
+
+We will be adjusting defaults in the future releases.
+
 #### TAR Response Format on Gateways
 
 Implemented [IPIP-288](https://github.com/ipfs/specs/pull/288) which adds

docs/config.md

@@ -243,9 +243,15 @@ documented in `ipfs config profile --help`.
 
 - `lowpower`
 
-  Reduces daemon overhead on the system. May affect node
+  Reduces daemon overhead on the system. Affects node
   functionality - performance of content discovery and data
-  fetching may be degraded.
+  fetching may be degraded. Local data won't be announced on routing systems like DHT.
+
+  - `Swarm.ConnMgr` set to maintain minimum number of p2p connections at a time.
+  - Disables [`Reprovider`](#reprovider) service → no CID will be announced on DHT and other routing systems(!)
+  - Disables AutoNAT.
+
+  Use this profile with caution.
 
 ## Types
 
@@ -1730,7 +1736,8 @@ be configured to keep. Kubo currently supports two connection managers:
 * none: never close idle connections.
 * basic: the default connection manager.
 
-Default: basic
+By default, this section is empty and the implicit defaults defined below
+are used.
 
 #### `Swarm.ConnMgr.Type`
 
@@ -1739,8 +1746,7 @@ management) and `"basic"`.
 
 Default: "basic".
 
-Type: `string` (when unset or `""`, the default connection manager is applied
-and all `ConnMgr` fields are ignored).
+Type: `optionalString` (default when unset or empty)
 
 #### Basic Connection Manager
 
@@ -1779,7 +1785,7 @@ trim down to.
 
 Default: `600`
 
-Type: `integer`
+Type: `optionalInteger`
 
 ##### `Swarm.ConnMgr.HighWater`
 
@@ -1789,7 +1795,7 @@ towards this limit.
 
 Default: `900`
 
-Type: `integer`
+Type: `optionalInteger`
 
 ##### `Swarm.ConnMgr.GracePeriod`
 
@@ -1798,7 +1804,7 @@ by the connection manager.
 
 Default: `"20s"`
 
-Type: `duration`
+Type: `optionalDuration`
 
 ### `Swarm.ResourceMgr`