tank: add metrics property for exporter

Author: pinheadmz

src/warnet/graph_schema.json

@@ -33,6 +33,9 @@
         "type": "boolean",
         "default": false,
         "comment": "Whether to attach a Prometheus data exporter to the tank"},
+      "metrics": {
+        "type": "string",
+        "comment": "A space-separated string of RPC queries to scrape by Prometheus"},
       "collect_logs": {
         "type": "boolean",
         "default": false,

src/warnet/tank.py

@@ -49,6 +49,7 @@ def __init__(self, index: int, warnet):
         self.bitcoin_config = ""
         self.netem = None
         self.exporter = False
+        self.metrics = None
         self.collect_logs = False
         self.build_args = ""
         self.lnnode: LNNode | None = None
@@ -107,6 +108,9 @@ def parse_graph_node(self, node):
             else:
                 raise Exception(f"Unsupported Lightning Network implementation: {options['impl']}")
 
+        if "metrics" in node:
+            self.metrics = node["metrics"]
+
         logger.debug(
             f"Parsed graph node: {self.index} with attributes: {[f'{key}={value}' for key, value in graph_properties.items()]}"
         )