ld: add commit-fee-offset option, update config schema

Changelog-Added: Added option --commit-fee-offset to potentially reduce feerate update disagreements

doc/getting-started/getting-started/configuration.md

@@ -313,6 +313,11 @@ The [`lightning-listconfigs`](ref:lightning-listconfigs) command will output a v
   The percentage of _estimatesmartfee 2/CONSERVATIVE_ to use for the commitment  
   transactions: default is 100.
 
+- **commit-feerate-offset**=_INTEGER_
+
+  The additional feerate a channel opener adds to their preferred feerate to
+  lessen the odds of a disconnect due to feerate disagreement (default 5).
+
 - **max-concurrent-htlcs**=_INTEGER_
 
   Number of HTLCs one channel can handle concurrently in each direction.  

doc/lightning-listconfigs.7.md

@@ -281,6 +281,9 @@ On success, an object is returned, containing:
   - **commit-fee** (object, optional):
     - **value\_int** (u64): field from config or cmdline, or default
     - **source** (string): source of configuration setting
+  - **commit-feerate-offset** (object, optional):
+    - **value\_int** (u32): field from config or cmdline, or default
+    - **source** (string): source of configuration setting
 - **# version** (string, optional): Special field indicating the current version **deprecated, removal in v24.05**
 - **plugins** (array of objects, optional) **deprecated, removal in v24.05**:
   - **path** (string): Full path of the plugin
@@ -359,6 +362,7 @@ On success, an object is returned, containing:
 - **developer** (boolean, optional): Whether developer mode is enabled *(added v23.08)*
 - **commit-fee** (u64, optional): The percentage of the 6-block fee estimate to use for commitment transactions **deprecated, removal in v24.05** *(added v23.05)*
 - **min-emergency-msat** (msat, optional): field from config or cmdline, or default *(added v23.08)*
+- **commit-feerate-offset** (u32, optional): additional commitment feerate applied by channel owner *(added v23.11)*
 
 [comment]: # (GENERATE-FROM-SCHEMA-END)
 
@@ -476,4 +480,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:cc7b6d10f93b9efb34ad76d0cc2273d29189a8dd7ef4acef2e5227755c279ea8)
+[comment]: # ( SHA256STAMP:245e056bdda7c8015917c89e243a0fd3bdd1512ca760da5d7f0a284cb3214ef7)

doc/lightningd-config.5.md

@@ -420,6 +420,11 @@ opens a channel before the channel is usable.
   The percentage of *estimatesmartfee 2/CONSERVATIVE* to use for the commitment
 transactions: default is 100.
 
+* **commit-feerate-offset**=*INTEGER*
+
+  The additional feerate a channel opener adds to their preferred feerate to
+lessen the odds of a disconnect due to feerate disagreement (default 5).
+
 * **max-concurrent-htlcs**=*INTEGER*
 
   Number of HTLCs one channel can handle concurrently in each direction.

doc/schemas/listconfigs.schema.json

@@ -1351,6 +1351,24 @@
               "description": "source of configuration setting"
             }
           }
+        },
+        "commit-feerate-offset": {
+          "type": "object",
+          "additionalProperties": false,
+          "required": [
+            "value_int",
+            "source"
+          ],
+          "properties": {
+            "value_int": {
+              "type": "u32",
+              "description": "field from config or cmdline, or default"
+            },
+            "source": {
+              "type": "string",
+              "description": "source of configuration setting"
+            }
+          }
         }
       }
     },
@@ -1770,6 +1788,11 @@
       "type": "msat",
       "added": "v23.08",
       "description": "field from config or cmdline, or default"
+    },
+    "commit-feerate-offset": {
+      "type": "u32",
+      "added": "v23.11",
+      "description": "additional commitment feerate applied by channel owner"
     }
   }
 }

lightningd/options.c

@@ -1578,6 +1578,10 @@ static void register_opts(struct lightningd *ld)
 	clnopt_witharg("--commit-fee", OPT_SHOWINT,
 		       opt_set_u64, opt_show_u64, &ld->config.commit_fee_percent,
 		       "Percentage of fee to request for their commitment");
+	clnopt_witharg("--commit-feerate-offset", OPT_SHOWINT,
+		       opt_set_u32, opt_show_u32, &ld->config.feerate_offset,
+		       "Additional feerate per kw to apply to feerate updates "
+		       "as the channel opener");
 	clnopt_witharg("--min-emergency-msat", OPT_SHOWMSATS,
 		       opt_set_sat_nondust, opt_show_sat, &ld->emergency_sat,
 		       "Amount to leave in wallet for spending anchor closes");

tests/test_misc.py

@@ -3831,3 +3831,30 @@ def test_even_sendcustommsg(node_factory):
     l2.daemon.wait_for_log(r'\[IN\] {}'.format(msg))
     l1.daemon.wait_for_log('Invalid unknown even msg')
     wait_for(lambda: l1.rpc.listpeers(l2.info['id'])['peers'] == [])
+
+
+def test_set_feerate_offset(node_factory, bitcoind):
+    opts = [{'commit-feerate-offset': 100}, {}]
+    l1, l2 = node_factory.get_nodes(2, opts=opts)
+    assert l1.daemon.is_in_log('Server started with public key')
+    configs = l1.rpc.listconfigs()['configs']
+    assert configs['commit-feerate-offset'] == {'source': 'cmdline',
+                                                'value_int': 100}
+    scid12 = l1.fundchannel(l2)[0]
+    # chanid = l1.get_channel_scid(l2)
+
+    # node 1 sets fees.
+    l1.set_feerates((14000, 11000, 7500, 3750))
+
+    l1.pay(l2, 200000000)
+    # First payment causes fee update, which should reflect the feerate offset.
+    l1.daemon.wait_for_log('lightningd: update_feerates: feerate = 11100, '
+                           'min=1875, max=150000, penalty=7500')
+    l2.daemon.wait_for_log('peer updated fee to 11100')
+    l2.pay(l1, 100000000)
+
+    # Now shutdown cleanly.
+    l1.rpc.close(scid12)
+
+    l1.daemon.wait_for_log(' to CLOSINGD_COMPLETE')
+    l2.daemon.wait_for_log(' to CLOSINGD_COMPLETE')