Add retry logic for getting default interface

lib/tc.js

@@ -6,27 +6,25 @@ const delay = (ms) => new Promise((result) => setTimeout(result, ms));
 async function getDefaultInterface() {
   const command =
     "sudo ip route | awk '/default/ {print $5; exit}' | tr -d '\n'";
-  const result = await shell(command);
 
-  if (result.stdout.length === 0 && result.stderr.length > 0) {
-    throw new Error(
-      'There was an error getting the default interface:\n\n' + result.stderr
-    );
-  } else if (result.stdout.length === 0) {
-    // lets do one retry
-    // The GitHub Actions sometimes cannot find the interface
-    await delay(1000);
+  // Retry a few times since GitHub Actions sometimes temporarily loses the default route
+  for (let attempt = 0; attempt < 3; attempt++) {
     const result = await shell(command);
-    if (result.stdout.length === 0) {
-      const result = await shell('sudo ip route show');
+    if (result.stdout.length > 0) {
+      return result.stdout;
+    }
+    if (result.stderr.length > 0) {
       throw new Error(
-        `There was an error getting the default interface ${result.stdout}`
+        'There was an error getting the default interface:\n\n' + result.stderr
       );
     }
-    return result.stdout;
+    await delay(1000);
   }
 
-  return result.stdout;
+  const result = await shell('sudo ip route show');
+  throw new Error(
+    `There was an error getting the default interface ${result.stdout}`
+  );
 }
 
 async function moduleProbe() {