From 96a5321ffe6180df65a9483cfc2075298c5f3fc3 Mon Sep 17 00:00:00 2001
From: bankisan <hello@bankisan.xyz>
Date: Mon, 4 Dec 2023 18:20:38 +0000
Subject: [PATCH] Reloading ponder.config.ts restarts the ponder app (#466)

- Add setup() method to server service to replicate interface of other services
- Reload ponder app when config file changes rather than exiting
- resetMetrics() method to metrics service
---
 packages/core/src/Ponder.ts              | 26 ++++++++++++++++++++++--
 packages/core/src/build/service.ts       |  1 -
 packages/core/src/metrics/service.ts     |  4 ++++
 packages/core/src/server/service.test.ts |  1 +
 packages/core/src/server/service.ts      |  3 +++
 5 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/packages/core/src/Ponder.ts b/packages/core/src/Ponder.ts
index 115af2f50..bf6d85458 100644
--- a/packages/core/src/Ponder.ts
+++ b/packages/core/src/Ponder.ts
@@ -199,7 +199,7 @@ export class Ponder {
 
     // One-time setup for some services.
     await this.syncStore.migrateUp();
-    await this.serverService.start();
+    this.serverService.setup();
 
     // Finally, load the schema + indexing functions which will trigger
     // the indexing service to reload (for the first time).
@@ -217,6 +217,7 @@ export class Ponder {
       },
     });
     this.serverService.registerDevRoutes();
+    await this.serverService.start();
 
     await Promise.all(
       this.syncServices.map(async ({ historical, realtime }) => {
@@ -241,6 +242,7 @@ export class Ponder {
 
     // If not using `dev`, can kill the build service here to avoid hot reloads.
     await this.buildService.kill();
+    await this.serverService.start();
 
     await Promise.all(
       this.syncServices.map(async ({ historical, realtime }) => {
@@ -302,6 +304,7 @@ export class Ponder {
       indexingStore: this.indexingStore,
     });
 
+    this.serverService.setup();
     await this.serverService.start();
 
     const { schema, graphqlSchema } = schemaResult;
@@ -358,11 +361,30 @@ export class Ponder {
 
   private registerServiceDependencies() {
     this.buildService.on("newConfig", async () => {
-      this.common.logger.fatal({
+      this.common.logger.info({
         service: "build",
         msg: "Detected change in ponder.config.ts",
       });
+      this.common.logger.info({
+        service: "app",
+        msg: "Reloading ponder, killing and restarting services",
+      });
       await this.kill();
+
+      // Clear all listeners. Will be added back in setup.
+      this.buildService.clearListeners();
+      this.syncServices.forEach(({ historical, realtime }) => {
+        historical.clearListeners();
+        realtime.clearListeners();
+      });
+      this.syncGatewayService.clearListeners();
+      this.serverService.clearListeners();
+      this.indexingService.clearListeners();
+      this.common.metrics.resetMetrics();
+
+      await this.setup();
+      // NOTE: We know we are in dev mode if the build service is receiving events. Build events are disabled in production.
+      await this.dev();
     });
 
     this.buildService.on("newSchema", async ({ schema, graphqlSchema }) => {
diff --git a/packages/core/src/build/service.ts b/packages/core/src/build/service.ts
index 51f1f6744..fc83e59d1 100644
--- a/packages/core/src/build/service.ts
+++ b/packages/core/src/build/service.ts
@@ -171,7 +171,6 @@ export class BuildService extends Emittery<BuildServiceEvents> {
     // TODO: Validate config lol
 
     this.emit("newConfig", { config });
-
     return config;
   }
 
diff --git a/packages/core/src/metrics/service.ts b/packages/core/src/metrics/service.ts
index 4c23a72b3..c53239512 100644
--- a/packages/core/src/metrics/service.ts
+++ b/packages/core/src/metrics/service.ts
@@ -201,4 +201,8 @@ export class MetricsService {
   async getMetrics() {
     return await this.registry.metrics();
   }
+
+  async resetMetrics() {
+    this.registry.resetMetrics();
+  }
 }
diff --git a/packages/core/src/server/service.test.ts b/packages/core/src/server/service.test.ts
index b46e3a967..84a639419 100644
--- a/packages/core/src/server/service.test.ts
+++ b/packages/core/src/server/service.test.ts
@@ -57,6 +57,7 @@ const setup = async ({
   await indexingStore.reload({ schema: s });
 
   const service = new ServerService({ common, indexingStore });
+  service.setup();
   await service.start();
   service.reloadGraphqlSchema({ graphqlSchema });
 
diff --git a/packages/core/src/server/service.ts b/packages/core/src/server/service.ts
index 75a1c936a..e686c3c06 100644
--- a/packages/core/src/server/service.ts
+++ b/packages/core/src/server/service.ts
@@ -43,6 +43,9 @@ export class ServerService extends Emittery<ServerEvents> {
     this.indexingStore = indexingStore;
     this.port = this.common.options.port;
     this.app = express();
+  }
+
+  setup() {
     this.registerRoutes();
   }