Add an onchain matcher

The onchain matcher offers the possibility to enforce policies
depending on the current onchain fees. The confirmation target
can be configured by the user (default: 6).

README.md

@@ -193,6 +193,12 @@ Currently available properties:
 | **node.min_shared_ratio_active** | match on active channels ratio with us |0..1|
 | **node.max_shared_ratio_inactive** | match on inactive channels ratio with us|0..1|
 | **node.min_shared_ratio_inactive** | match on inactive channels ratio with us|0..1|
+|||
+|ONCHAIN||
+| **onchain.conf_target** | defines the confirmation target that is used for the determination of the onchain fee rate (default: 6)|# blocks|
+| **onchain.min_fee_rate** | match on the onchain fee rate|# sat per vbyte|
+| **onchain.max_fee_rate** |  match on the onchain fee rate|# sat per vbyte|
+
 
 File references should contain 1 item per line
 ### Strategies

charge_lnd/policy.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 import sys
 import re
-from .strategy import StrategyDelegate
+from .strategy import StrategyDelegate, DEFAULT_CONF_TARGET
 from . import fmt
 
 def debug(message):
@@ -108,8 +108,9 @@ class Policies:
 
     def eval_matchers(self, channel, policy, policy_conf):
         map = {
-            'chan'  : self.match_by_chan,
-            'node'  : self.match_by_node
+            'chan'   : self.match_by_chan,
+            'node'   : self.match_by_node,
+            'onchain': self.match_by_onchain
         }
         namespaces = []
         for key in policy_conf.keys():
@@ -379,6 +380,23 @@ class Policies:
                 return False
 
         return True
+    
+    def match_by_onchain(self, channel, config):
+        accepted = ['min_fee_rate', 'max_fee_rate', 'conf_target']
+        
+        for key in config.keys():
+            if key.split(".")[0] == 'onchain' and key.split(".")[1] not in accepted:
+                raise Exception("Unknown property '%s'" % key)
+            
+        fee_rate = self.lnd.get_fee_estimate(config.getint('onchain.conf_target', DEFAULT_CONF_TARGET))
+        
+        if 'onchain.max_fee_rate' in config and not config.getfloat('onchain.max_fee_rate') >= fee_rate:
+            return False
+                    
+        if 'onchain.min_fee_rate' in config and not config.getfloat('onchain.min_fee_rate') <= fee_rate:
+            return False
+        
+        return True
 
     # simple minutes/hours/days format, e.g. '5m', '3h'
     def parse_activity_period(self, period):

charge_lnd/strategy.py

@@ -13,6 +13,7 @@ def debug(message):
 
 KEEP='keep'
 DONTCARE='dontcare'
+DEFAULT_CONF_TARGET=6
 
 def is_defined(x):
     return x not in [KEEP, DONTCARE] and x is not None
@@ -206,7 +207,7 @@ def strategy_onchain_fee(channel, policy, **kwargs):
     if policy.getint('min_fee_ppm_delta',-1) < 0:
         policy.set('min_fee_ppm_delta', 10) # set delta to 10 if not defined
 
-    numblocks = policy.getint('onchain_fee_numblocks', 6)
+    numblocks = policy.getint('onchain_fee_numblocks', DEFAULT_CONF_TARGET)
     sat_per_byte = lnd.get_fee_estimate(numblocks)
     if sat_per_byte < 1:
         return (None, None, None, None, None)

examples/complex-ruleset.config

@@ -16,6 +16,11 @@ min_fee_ppm_delta = 5
 chan.max_base_fee_msat = 0
 base_fee_msat = 0
 
+[onchain-congestion]
+# if the onchain fee rate is high (>= 500 sat/vbyte) we increase the base fee to 5 sat
+onchan.min_fee_rate = 500
+base_fee_msat = 5_000
+
 [ignored_channels]
 # don't let charge-lnd set fees (strategy=ignore) for channels to/from the specified nodes
 node.id = 02da8d5a759ee9e4438da617cfdb61c87f723fb76c4b6371b877d0347abe953a4f,