fix(hosting): name the function and regions in the wrong-region rewrite error

CHANGELOG.md

@@ -1 +1,2 @@
 - Ensured the Firebase Hosting API is enabled before deploying and running other Hosting commands.
+- Improved the error shown when a Hosting rewrite targets a function in the wrong region. It now names the function, the rewrite region, and the regions where the function was found. (#11289)

src/deploy/hosting/convertConfig.spec.ts

@@ -535,7 +535,83 @@ describe("convertConfig", () => {
             version: "14",
           },
         ),
-      ).to.eventually.be.rejectedWith(FirebaseError);
+      ).to.eventually.be.rejectedWith(
+        FirebaseError,
+        `Rewrite for function \`${FUNCTION_ID}\` in firebase.json targets region \`asia-northeast1\`, ` +
+          `but \`${FUNCTION_ID}\` was only found in \`europe-west1\`. Update the rewrite's \`region\` ` +
+          `in firebase.json to that region.`,
+      );
+    });
+    it("should name the deployed region when rewrite points to an existing function in the wrong region", async () => {
+      existingBackendStub.resolves(
+        backend.of({
+          id: FUNCTION_ID,
+          project: PROJECT_ID,
+          entryPoint: FUNCTION_ID,
+          runtime: "nodejs22",
+          region: "europe-west1",
+          platform: "gcfv2",
+          httpsTrigger: {},
+        }),
+      );
+      await expect(
+        convertConfig(
+          { projectId: "1" },
+          {},
+          {
+            config: {
+              site: "foo",
+              rewrites: [
+                { glob: "/foo", function: { functionId: FUNCTION_ID, region: "us-central1" } },
+              ],
+            },
+            version: "14",
+          },
+        ),
+      ).to.eventually.be.rejectedWith(
+        FirebaseError,
+        `Rewrite for function \`${FUNCTION_ID}\` in firebase.json targets region \`us-central1\`, ` +
+          `but \`${FUNCTION_ID}\` was only found in \`europe-west1\`. Update the rewrite's \`region\` ` +
+          `in firebase.json to that region.`,
+      );
+    });
+    it("should list every region when rewrite matches none of a multi-region function", async () => {
+      const endpointIn = (region: string): backend.Endpoint => ({
+        id: FUNCTION_ID,
+        project: PROJECT_ID,
+        entryPoint: FUNCTION_ID,
+        runtime: "nodejs22",
+        region,
+        platform: "gcfv2",
+        httpsTrigger: {},
+      });
+      await expect(
+        convertConfig(
+          { projectId: "1" },
+          {
+            functions: {
+              default: {
+                wantBackend: backend.of(endpointIn("europe-west1"), endpointIn("us-east1")),
+                haveBackend: backend.empty(),
+              },
+            },
+          },
+          {
+            config: {
+              site: "foo",
+              rewrites: [
+                { glob: "/foo", function: { functionId: FUNCTION_ID, region: "asia-northeast1" } },
+              ],
+            },
+            version: "14",
+          },
+        ),
+      ).to.eventually.be.rejectedWith(
+        FirebaseError,
+        `Rewrite for function \`${FUNCTION_ID}\` in firebase.json targets region \`asia-northeast1\`, ` +
+          `but \`${FUNCTION_ID}\` was only found in \`europe-west1\`, \`us-east1\`. Update the rewrite's ` +
+          `\`region\` in firebase.json to one of these regions.`,
+      );
     });
     it("should throw when rewrite points to function being deleted", async () => {
       await expect(

src/deploy/hosting/convertConfig.ts

@@ -61,10 +61,7 @@
   if (endpoints.length === 0) {
     return { matchingEndpoint: undefined, foundMatchingId: false };
   }
-  if (endpoints.length === 1) {
-    if (region && region !== endpoints[0].region) {
-      return { matchingEndpoint: undefined, foundMatchingId: true };
-    }
+  if (!region && endpoints.length === 1) {
     return { matchingEndpoint: endpoints[0], foundMatchingId: true };
   }
   if (!region) {
@@ -81,10 +78,16 @@
     );
     return { matchingEndpoint: us, foundMatchingId: true };
   }
-  return {
-    matchingEndpoint: endpoints.find((e) => e.region === region),
-    foundMatchingId: true,
-  };
+  const matchingEndpoint = endpoints.find((e) => e.region === region);
+  if (!matchingEndpoint) {
+    const regions = endpoints.map((e) => `\`${e.region}\``).join(", ");
+    throw new FirebaseError(
+      `Rewrite for function \`${id}\` in firebase.json targets region \`${region}\`, ` +
+        `but \`${id}\` was only found in ${regions}. Update the rewrite's \`region\` ` +
+        `in firebase.json to ${endpoints.length === 1 ? "that region" : "one of these regions"}.`,
+    );
+  }
+  return { matchingEndpoint, foundMatchingId: true };
 }
 
 /**
@@ -165,15 +168,6 @@
         : existingEndpointSearch?.matchingEndpoint;
 
       if (!endpoint) {
-        // If we find a function matching the function ID we are looking for in either
-        // existing or currently-deploying backends, we consider it a firebase function.
-        // In this case, we throw an error if the rewrite doesn't point to a valid region.
-        if (deployingEndpointSearch.foundMatchingId || existingEndpointSearch?.foundMatchingId) {
-          throw new FirebaseError(
-            `Unable to find a valid endpoint for function. Functions matching the rewrite
-  are present but in the wrong region.`,
-          );
-        }
         // This could possibly succeed if there has been a function written
         // outside firebase tooling. But it will break in v2. We might need to
         // revisit this.
@@ -263,7 +257,7 @@
     // 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'",