add labels and conntrack stats to prometheus output

src/capport/stats.py

@@ -1,7 +1,9 @@
 from __future__ import annotations
 
+import argparse
+import dataclasses
 import ipaddress
-import sys
+import typing
 
 import trio
 
@@ -11,18 +13,39 @@ import capport.utils.nft_set
 from . import cptypes
 
 
-def print_metric(name: str, mtype: str, value, *, now: int | None = None, help: str | None = None):
-    # no labels in our names for now, always print help and type
+@dataclasses.dataclass(kw_only=True, slots=True)
+class MetricPrinter:
+    args: CliArguments
+    now: int | None = None
+    _known_names: set[str] = dataclasses.field(default_factory=set, init=None)
+    _now_str: str = dataclasses.field(init=False)
+    _label_str: str = dataclasses.field(init=False)
+
+    def __post_init__(self) -> None:
+        if not self.now is None:
+            self._now_str = f" {self.now}"
+        else:
+            self._now_str = ""
+        labels = []
+        if self.args.instance:
+            labels.append(f"instance={self.args.instance!r}")
+        labels.append(f"interface={self.args.interface!r}")
+        self._label_str = "{" + ",".join(labels) + "}"
+
+    def print_metric(self, *, name: str, mtype: str, value: typing.Any, help: str | None = None):
+        if not name in self._known_names:
+            self._known_names.add(name)
             if help:
                 print(f"# HELP {name} {help}")
             print(f"# TYPE {name} {mtype}")
-    if now:
-        print(f"{name} {value} {now}")
-    else:
-        print(f"{name} {value}")
+        print(f"{name}{self._label_str} {value} {self._now_str}")
+
+    def print_gauge(self, name: str, value: int | float, help: str | None = None):
+        self.print_metric(name=name, mtype="gauge", value=value, help=help)
 
 
-async def amain(client_ifname: str):
+async def amain(args: CliArguments):
+    printer = MetricPrinter(args=args)
     ns = capport.utils.nft_set.NftSet()
     captive_allowed_entries: set[cptypes.MacAddress] = {entry["mac"] for entry in ns.list()}
     seen_allowed_entries: set[cptypes.MacAddress] = set()
@@ -33,7 +56,7 @@ async def amain(client_ifname: str):
     unique_ipv6 = set()
     async with capport.utils.ipneigh.connect() as ipn:
         ipn.ip.strict_check = True
-        async for (mac, addr) in ipn.dump_neighbors(client_ifname):
+        async for (mac, addr) in ipn.dump_neighbors(args.interface):
             if mac in captive_allowed_entries:
                 seen_allowed_entries.add(mac)
             unique_clients.add(mac)
@@ -43,50 +66,74 @@ async def amain(client_ifname: str):
             else:
                 total_ipv6 += 1
                 unique_ipv6.add(mac)
-    print_metric(
+    printer.print_gauge(
         "capport_allowed_macs",
-        "gauge",
         len(captive_allowed_entries),
         help="Number of allowed client mac addresses",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_allowed_neigh_macs",
-        "gauge",
         len(seen_allowed_entries),
         help="Number of allowed client mac addresses seen in neighbor cache",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_unique",
-        "gauge",
         len(unique_clients),
         help="Number of clients (mac addresses) in client network seen in neighbor cache",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_unique_ipv4",
-        "gauge",
         len(unique_ipv4),
         help="Number of IPv4 clients (unique per mac) in client network seen in neighbor cache",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_unique_ipv6",
-        "gauge",
         len(unique_ipv6),
         help="Number of IPv6 clients (unique per mac) in client network seen in neighbor cache",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_total_ipv4",
-        "gauge",
         total_ipv4,
         help="Number of IPv4 addresses seen in neighbor cache",
     )
-    print_metric(
+    printer.print_gauge(
         "capport_total_ipv6",
-        "gauge",
         total_ipv6,
         help="Number of IPv6 addresses seen in neighbor cache",
     )
+    with open('/proc/sys/net/netfilter/nf_conntrack_count') as f:
+        printer.print_gauge(
+            "nf_conntrack_count",
+            int(f.readline()),
+            help="Conntrack count",
+        )
+    with open('/proc/sys/net/netfilter/nf_conntrack_max') as f:
+        printer.print_gauge(
+            "nf_conntrack_max",
+            int(f.readline()),
+            help="Conntrack max",
+        )
+
+
+@dataclasses.dataclass
+class CliArguments:
+    interface: str
+    instance: str | None
+
+    def __init__(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument(
+            "--interface",
+            required=True,
+            help="Name of network interface clients are connected to (to look for IP neighbors)",
+        )
+        parser.add_argument("--instance", help="Name of instance (to tag metrics with)")
+        args = parser.parse_args()
+
+        self.interface = args.interface
+        self.instance = args.instance
 
 
 def main():
-    assert len(sys.argv) == 2, "Need name of client interface as argument"
-    trio.run(amain, sys.argv[1])
+    args = CliArguments()
+    trio.run(amain, args)

stats-to-prometheus-collector.sh

@@ -16,7 +16,7 @@ fi
 targetname="/var/lib/prometheus/node-exporter/capport-${instance}.prom"
 tmpname="${targetname}.$$"
 
-if ./stats.sh "${ifname}" > "${tmpname}"; then
+if ./stats.sh --instance "${instance}" --interface "${ifname}" > "${tmpname}"; then
     mv "${tmpname}" "${targetname}"
 else
     rm "${tmpname}"