Prevent pinTags + minInstances from any functions rewrite, not just w…

…eb frameworks

src/deploy/hosting/convertConfig.ts

@@ -218,6 +218,19 @@
         },
       };
       if (rewrite.function.pinTag) {
+        // b/319616292. Functions currently set min instances at the revision
+        // level and Run will maintain all those min instances for each revision
+        // whenever that revision is accessible (e.g. via a traffic tag). This
+        // can lead to customers paying lots of money with zero benefit. Until
+        // Run makes min instances dynamic, we must not allow both features to
+        // be used at the same time.
+        if (endpoint.minInstances) {
+          throw new FirebaseError(
+            `Function ${endpoint.id} has minInstances set and is in a rewrite ` +
+              "pinTags=true. These features are not currently compatible with each " +
+              "other."
+          );
+        }
         experiments.assertEnabled("pintags", "pin a function version");
         apiRewrite.run.tag = runTags.TODO_TAG_NAME;
       }
@@ -250,7 +263,7 @@
     // kind of rewrite and we haven't yet handled it.
     try {
       assertExhaustive(rewrite);
     } catch (e: any) {
       throw new FirebaseError(
         "Invalid hosting rewrite config in firebase.json. " +
           "A rewrite config must specify 'destination', 'function', 'dynamicLinks', or 'run'"