setconfig: new command to set (a few!) config parameters dynamically

common/configvar.h

@@ -58,6 +58,8 @@ struct configvar {
 #define OPT_SHOWMSATS (1 << (OPT_USER_START+4))
 /* listconfigs should treat as a literal boolean `true` or `false` */
 #define OPT_SHOWBOOL (1 << (OPT_USER_START+5))
+/* Can be changed at runtime */
+#define OPT_DYNAMIC (1 << (OPT_USER_START+6))
 
 /* Use this instead of opt_register_*_arg if you want OPT_* from above */
 #define clnopt_witharg(names, type, cb, show, arg, desc)		\

doc/Makefile

@@ -89,6 +89,7 @@ MANPAGES := doc/lightning-cli.1 \
 	doc/lightning-sendonionmessage.7 \
 	doc/lightning-sendpay.7 \
 	doc/lightning-setchannel.7 \
+	doc/lightning-setconfig.7 \
 	doc/lightning-setpsbtversion.7 \
 	doc/lightning-sendcustommsg.7 \
 	doc/lightning-signinvoice.7 \

doc/PLUGINS.md

@@ -99,7 +99,8 @@ example:
       "type": "string",
       "default": "World",
       "description": "What name should I call you?",
-      "deprecated": false
+      "deprecated": false,
+	  "dynamic": false
     }
   ],
   "rpcmethods": [
@@ -143,7 +144,7 @@ example:
 During startup the `options` will be added to the list of command line options that
 `lightningd` accepts. If any `options` "name" is already taken startup will abort. The above will add a `--greeting` option with a
 default value of `World` and the specified description. *Notice that
-currently string, integers, bool, and flag options are supported.*
+currently string, integers, bool, and flag options are supported.*  If an option specifies `dynamic`: `true`, then it should allow a `setvalue` call for that option after initialization.
 
 The `rpcmethods` are methods that will be exposed via `lightningd`'s
 JSON-RPC over Unix-Socket interface, just like the builtin
@@ -254,11 +255,6 @@ Here's an example option set, as sent in response to `getmanifest`
   ],
 ```
 
-**Note**: `lightningd` command line options are only parsed during startup and their
-values are not remembered when the plugin is stopped or killed.
-For dynamic plugins started with `plugin start`, options can be
-passed as extra arguments to that [command][lightning-plugin].
-
 
 #### Custom notifications
 

doc/index.rst

@@ -122,6 +122,7 @@ Core Lightning Documentation
    lightning-sendpay <lightning-sendpay.7.md>
    lightning-sendpsbt <lightning-sendpsbt.7.md>
    lightning-setchannel <lightning-setchannel.7.md>
+   lightning-setconfig <lightning-setconfig.7.md>
    lightning-setpsbtversion <lightning-setpsbtversion.7.md>
    lightning-signinvoice <lightning-signinvoice.7.md>
    lightning-signmessage <lightning-signmessage.7.md>

doc/lightning-listconfigs.7.md

@@ -9,12 +9,27 @@ SYNOPSIS
 DESCRIPTION
 -----------
 
-*config* (optional) is a configuration option name, or "plugin" to show plugin options
+*config* (optional) is a configuration option name to restrict return.
 
-The **listconfigs** RPC command to list all configuration options, or with *config* only a selection.
+The **listconfigs** RPC command to list all configuration options, or with *config* only one.
 
 The returned values reflect the current configuration, including
-showing default values (`dev-` options are not shown).
+showing default values (`dev-` options are not shown unless specified as *config* explicitly).
+
+Note: as plugins can add options, not all configuration settings are
+listed here!  The format of each entry is as follows:
+
+- **source** (string): source of configuration setting (`file`:`linenum`)
+- **dynamic** (boolean, optional): true if this option is settable via setconfig
+- **plugin** (string, optional): set if this is from a plugin
+
+Depending on the option type, exactly one of the following is present:
+
+- **set** (boolean, optional): for simple flag options
+- **value\_str** (string, optional): for string options
+- **value\_msat** (msat, optional): for msat options
+- **value\_int** (integer, optional): for integer options
+- **value\_bool** (boolean, optional): for boolean options
 
 EXAMPLE JSON REQUEST
 --------------------
@@ -177,6 +192,7 @@ On success, an object is returned, containing:
   - **min-capacity-sat** (object, optional):
     - **value\_int** (u64): field from config or cmdline, or default
     - **source** (string): source of configuration setting
+    - **dynamic** (boolean, optional): Can this be set by setconfig() (always *true*)
   - **addr** (object, optional):
     - **values\_str** (array of strings):
       - field from config or cmdline
@@ -447,4 +463,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:2b3588b395919162c122cd386f0f4b320d906d0190e706bfa1b68db4126e7ee2)
+[comment]: # ( SHA256STAMP:0440e4634e4a28681323f891307c7bb61143aacad4824f952f24f027a7543835)

doc/lightning-setconfig.7.md

@@ -0,0 +1,59 @@
+lightning-setconfig -- Dynamically change some config options
+=============================================================
+
+SYNOPSIS
+--------
+
+**setconfig** *config* [*val*]
+
+DESCRIPTION
+-----------
+
+The **setconfig** RPC command allows you set the (dynamic) configuration option named by `config`: options which take a value (as separate from simple flag options) also need a `val` parameter.
+
+This new value will *also* be written at the end of the config file, for persistence across restarts (and any old value commented out).
+
+You can see what options are dynamically adjustable using lightning-listconfigs(7).  Note that you can also adjust existing options for stopped plugins; they will have an effect when the plugin is restarted.
+
+
+RETURN VALUE
+------------
+
+[comment]: # (GENERATE-FROM-SCHEMA-START)
+On success, an object containing **config** is returned.  It is an object containing:
+
+- **config** (string): name of the config variable which was set
+- **source** (string): source of configuration setting (`file`:`linenum`)
+- **dynamic** (boolean): whether this option is settable via setconfig (always *true*)
+- **plugin** (string, optional): the plugin this configuration setting is for
+- **set** (boolean, optional): for simple flag options
+- **value\_str** (string, optional): for string options
+- **value\_msat** (msat, optional): for msat options
+- **value\_int** (integer, optional): for integer options
+- **value\_bool** (boolean, optional): for boolean options
+
+[comment]: # (GENERATE-FROM-SCHEMA-END)
+
+ERRORS
+------
+
+The following error codes may occur:
+- -32602: JSONRPC2\_INVALID\_PARAMS, i.e. the parameter is not dynamic, or the val was invalid.
+
+AUTHOR
+------
+
+Rusty Russell <<rusty@rustcorp.com.au>> is mainly responsible for this
+feature.
+
+SEE ALSO
+--------
+
+lightningd-config(5), lightning-listconfigs(7)
+
+RESOURCES
+---------
+
+Main web site: <https://github.com/ElementsProject/lightning>
+
+[comment]: # ( SHA256STAMP:d61e4e6eea7b8c214644334ee194b273aef2a8a26465adfcd685be0d70653966)

doc/lightningd-config.5.md

@@ -14,6 +14,8 @@ file (default: **$HOME/.lightning/config**) then a network-specific
 configuration file (default: **$HOME/.lightning/testnet/config**).  This can
 be changed: see *--conf* and *--lightning-dir*.
 
+Note that some configuration options, marked *dynamic*m can be changed at runtime: see lightning-setconfig(7).
+
 General configuration files are processed first, then network-specific
 ones, then command line options: later options override earlier ones
 except *addr* options and *log-level* with subsystems, which
@@ -316,7 +318,7 @@ millionths, so 10000 is 1%, 1000 is 0.1%. Changing this value will only
 affect new channels and not existing ones. If you want to change fees
 for existing channels, use the RPC call lightning-setchannel(7).
 
-* **min-capacity-sat**=*SATOSHI*
+* **min-capacity-sat**=*SATOSHI* [*dynamic*]
 
   Default: 10000. This value defines the minimal effective channel
 capacity in satoshi to accept for channel opening requests. This will
@@ -440,32 +442,32 @@ accepted, and ignored.
 
 ### Cleanup control options:
 
-* **autoclean-cycle**=*SECONDS* [plugin `autoclean`]
+* **autoclean-cycle**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   Perform search for things to clean every *SECONDS* seconds (default
 3600, or 1 hour, which is usually sufficient).
 
-* **autoclean-succeededforwards-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-succeededforwards-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old successful forwards (`settled` in listforwards `status`) have to be before deletion (default 0, meaning never).
 
-* **autoclean-failedforwards-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-failedforwards-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old failed forwards (`failed` or `local_failed` in listforwards `status`) have to be before deletion (default 0, meaning never).
 
-* **autoclean-succeededpays-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-succeededpays-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old successful payments (`complete` in listpays `status`) have to be before deletion (default 0, meaning never).
 
-* **autoclean-failedpays-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-failedpays-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old failed payment attempts (`failed` in listpays `status`) have to be before deletion (default 0, meaning never).
 
-* **autoclean-paidinvoices-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-paidinvoices-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old invoices which were paid (`paid` in listinvoices `status`) have to be before deletion (default 0, meaning never).
 
-* **autoclean-expiredinvoices-age**=*SECONDS* [plugin `autoclean`]
+* **autoclean-expiredinvoices-age**=*SECONDS* [plugin `autoclean`, *dynamic*]
 
   How old invoices which were not paid (and cannot be) (`expired` in listinvoices `status`) before deletion (default 0, meaning never).
 

doc/schemas/listconfigs.schema.json

@@ -834,6 +834,13 @@
             "source": {
               "type": "string",
               "description": "source of configuration setting"
+            },
+            "dynamic": {
+              "type": "boolean",
+              "enum": [
+                true
+              ],
+              "description": "Can this be set by setconfig()"
             }
           }
         },

doc/schemas/setconfig.request.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "additionalProperties": false,
+  "required": [
+    "config"
+  ],
+  "added": "v23.08",
+  "properties": {
+    "config": {
+      "type": "string"
+    },
+    "val": {}
+  }
+}

doc/schemas/setconfig.schema.json

@@ -0,0 +1,62 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "additionalProperties": false,
+  "added": "v23.08",
+  "required": [
+    "config"
+  ],
+  "properties": {
+    "config": {
+      "type": "object",
+      "description": "config settings after completion",
+      "additionalProperties": false,
+      "required": [
+        "config",
+        "source",
+        "dynamic"
+      ],
+      "properties": {
+        "config": {
+          "type": "string",
+          "description": "name of the config variable which was set"
+        },
+        "source": {
+          "type": "string",
+          "description": "source of configuration setting (`file`:`linenum`)"
+        },
+        "plugin": {
+          "type": "string",
+          "description": "the plugin this configuration setting is for"
+        },
+        "dynamic": {
+          "type": "boolean",
+          "enum": [
+            true
+          ],
+          "description": "whether this option is settable via setconfig"
+        },
+        "set": {
+          "type": "boolean",
+          "description": "for simple flag options"
+        },
+        "value_str": {
+          "type": "string",
+          "description": "for string options"
+        },
+        "value_msat": {
+          "type": "msat",
+          "description": "for msat options"
+        },
+        "value_int": {
+          "type": "integer",
+          "description": "for integer options"
+        },
+        "value_bool": {
+          "type": "boolean",
+          "description": "for boolean options"
+        }
+      }
+    }
+  }
+}

lightningd/Makefile

@@ -40,6 +40,7 @@ LIGHTNINGD_SRC :=				\
 	lightningd/watch.c
 
 LIGHTNINGD_SRC_NOHDR :=				\
+	lightningd/configs.c			\
 	lightningd/datastore.c			\
 	lightningd/ping.c			\
 	lightningd/offer.c			\