Implement exit node check-in tracking and adjust logging for connection errors

server/lib/exitNodes/exitNodeCheckIn.ts

@@ -0,0 +1,14 @@
+// Tracks, per process lifetime, whether a given exit node has ever checked in
+// (called /gerbil/get-config) since this Pangolin instance started. This lets
+// callers distinguish "gerbil hasn't come up yet" (expected briefly after a
+// restart, since gerbil depends on pangolin's container starting first) from
+// "gerbil was reachable and now isn't" (a real problem worth an error log).
+const checkedInExitNodeIds = new Set<number>();
+
+export function markExitNodeCheckedIn(exitNodeId: number): void {
+    checkedInExitNodeIds.add(exitNodeId);
+}
+
+export function hasExitNodeCheckedIn(exitNodeId: number): boolean {
+    return checkedInExitNodeIds.has(exitNodeId);
+}

server/lib/exitNodes/exitNodeComms.ts

@@ -1,6 +1,7 @@
 import axios from "axios";
 import logger from "@server/logger";
 import { ExitNode } from "@server/db";
+import { hasExitNodeCheckedIn } from "./exitNodeCheckIn";
 
 interface ExitNodeRequest {
     remoteType?: string;
@@ -72,13 +73,19 @@ export async function sendToExitNode(
 
         return response.data;
     } catch (error) {
-        if (axios.isAxiosError(error)) {
-            logger.error(
-                `Error making ${method} request (can Pangolin see Gerbil HTTP API?) for exit node at ${exitNode.reachableAt} (status: ${error.response?.status}): ${error.message}`
-            );
+        const message = axios.isAxiosError(error)
+            ? `Error making ${method} request (can Pangolin see Gerbil HTTP API?) for exit node at ${exitNode.reachableAt} (status: ${error.response?.status}): ${error.message}`
+            : `Error making ${method} request for exit node at ${exitNode.reachableAt}: ${error}`;
+
+        // The exit node (gerbil) may still be starting up and not yet
+        // reachable. Until it has checked in at least once, log this at a
+        // lower level since it's expected; once it has checked in, a
+        // connection failure is a real problem.
+        if (hasExitNodeCheckedIn(exitNode.exitNodeId)) {
+            logger.error(message);
         } else {
-            logger.error(
-                `Error making ${method} request for exit node at ${exitNode.reachableAt}: ${error}`
+            logger.warn(
+                `${message} (exit node has not checked in yet since startup, this is expected briefly)`
             );
         }
         throw error;

server/lib/exitNodes/index.ts

@@ -1,5 +1,6 @@
 export * from "./exitNodes";
 export * from "./exitNodeComms";
+export * from "./exitNodeCheckIn";
 export * from "./subnet";
 export * from "./getCurrentExitNodeId";
 export * from "./calculateExitNodeWeight";