Health Check Improvements

.changeset/bright-gifts-turn.md

@@ -0,0 +1,23 @@
+---
+'@powersync/service-core': minor
+---
+
+- Added `ServiceContextMode` to `ServiceContext`. This conveys the mode in which the PowerSync service was started in.
+- `RouterEngine` is now always present on `ServiceContext`. The router will only configure actual servers, when started, if routes have been registered.
+- Added typecasting to `!env` YAML custom tag function. YAML config environment variable substitution now supports casting string environment variables to `number` and `boolean` types.
+
+```yaml
+replication:
+  connections: []
+
+storage:
+  type: mongodb
+
+api:
+  parameters:
+    max_buckets_per_connection: !env PS_MAX_BUCKETS::number
+
+healthcheck:
+  probes:
+    use_http: !env PS_MONGO_HEALTHCHECK::boolean
+```

.changeset/khaki-cows-thank.md

@@ -0,0 +1,32 @@
+---
+'@powersync/service-image': minor
+---
+
+- Added typecasting to `!env` YAML custom tag function. YAML config environment variable substitution now supports casting string environment variables to `number` and `boolean` types.
+
+```yaml
+replication:
+  connections: []
+
+storage:
+  type: mongodb
+
+api:
+  parameters:
+    max_buckets_per_connection: !env PS_MAX_BUCKETS::number
+
+healthcheck:
+  probes:
+    use_http: !env PS_MONGO_HEALTHCHECK::boolean
+```
+
+- Added the ability to customize healthcheck probe exposure in the configuration. Backwards compatibility is maintained if no `healthcheck->probes` config is provided.
+
+```yaml
+healthcheck:
+  probes:
+    # Health status can be accessed by reading files (previously always enabled)
+    use_filesystem: true
+    # Health status can be accessed via HTTP requests (previously enabled for API and UNIFIED service modes)
+    use_http: true
+```

.changeset/little-pianos-fetch.md

@@ -0,0 +1,5 @@
+---
+'@powersync/service-types': minor
+---
+
+Added healthcheck types to PowerSyncConfig

.changeset/shaggy-bikes-relax.md

@@ -0,0 +1,5 @@
+---
+'@powersync/lib-services-framework': minor
+---
+
+Switched default health check probe mechanism from filesystem to in-memory implementation. Consumers now need to manually opt-in to filesystem probes.

.changeset/thick-wolves-invent.md

@@ -0,0 +1,5 @@
+---
+'@powersync/service-module-core': minor
+---
+
+Initial core module release. This moves RouterEngine API route registrations, health check probe configuration and metrics configuration from the service runners to this shared module.

libs/lib-services/src/container.ts

@@ -1,9 +1,14 @@
+import { ServiceAssertionError } from '@powersync/service-errors';
 import _ from 'lodash';
 import { ErrorReporter } from './alerts/definitions.js';
 import { NoOpReporter } from './alerts/no-op-reporter.js';
 import { MigrationManager } from './migrations/MigrationManager.js';
-import { ProbeModule, TerminationHandler, createFSProbe, createTerminationHandler } from './signals/signals-index.js';
-import { ServiceAssertionError } from '@powersync/service-errors';
+import {
+  ProbeModule,
+  TerminationHandler,
+  createInMemoryProbe,
+  createTerminationHandler
+} from './signals/signals-index.js';
 
 export enum ContainerImplementation {
   REPORTER = 'reporter',
@@ -45,7 +50,7 @@ export type ServiceIdentifier<T = unknown> = string | symbol | Newable<T> | Abst
 
 const DEFAULT_GENERATORS: ContainerImplementationDefaultGenerators = {
   [ContainerImplementation.REPORTER]: () => NoOpReporter,
-  [ContainerImplementation.PROBES]: () => createFSProbe(),
+  [ContainerImplementation.PROBES]: () => createInMemoryProbe(),
   [ContainerImplementation.TERMINATION_HANDLER]: () => createTerminationHandler(),
   [ContainerImplementation.MIGRATION_MANAGER]: () => new MigrationManager()
 };

modules/module-core/CHANGELOG.md

@@ -0,0 +1 @@
+# @powersync/service-module-core

modules/module-core/LICENSE

@@ -0,0 +1,67 @@
+# Functional Source License, Version 1.1, Apache 2.0 Future License
+
+## Abbreviation
+
+FSL-1.1-Apache-2.0
+
+## Notice
+
+Copyright 2023-2024 Journey Mobile, Inc.
+
+## Terms and Conditions
+
+### Licensor ("We")
+
+The party offering the Software under these Terms and Conditions.
+
+### The Software
+
+The "Software" is each version of the software that we make available under these Terms and Conditions, as indicated by our inclusion of these Terms and Conditions with the Software.
+
+### License Grant
+
+Subject to your compliance with this License Grant and the Patents, Redistribution and Trademark clauses below, we hereby grant you the right to use, copy, modify, create derivative works, publicly perform, publicly display and redistribute the Software for any Permitted Purpose identified below.
+
+### Permitted Purpose
+
+A Permitted Purpose is any purpose other than a Competing Use. A Competing Use means making the Software available to others in a commercial product or service that:
+
+1. substitutes for the Software;
+2. substitutes for any other product or service we offer using the Software that exists as of the date we make the Software available; or
+3. offers the same or substantially similar functionality as the Software.
+
+Permitted Purposes specifically include using the Software:
+
+1. for your internal use and access;
+2. for non-commercial education;
+3. for non-commercial research; and
+4. in connection with professional services that you provide to a licensee using the Software in accordance with these Terms and Conditions.
+
+### Patents
+
+To the extent your use for a Permitted Purpose would necessarily infringe our patents, the license grant above includes a license under our patents. If you make a claim against any party that the Software infringes or contributes to the infringement of any patent, then your patent license to the Software ends immediately.
+
+### Redistribution
+
+The Terms and Conditions apply to all copies, modifications and derivatives of the Software.
+If you redistribute any copies, modifications or derivatives of the Software, you must include a copy of or a link to these Terms and Conditions and not remove any copyright notices provided in or with the Software.
+
+### Disclaimer
+
+THE SOFTWARE IS PROVIDED "AS IS" AND WITHOUT WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, TITLE OR NON-INFRINGEMENT.
+IN NO EVENT WILL WE HAVE ANY LIABILITY TO YOU ARISING OUT OF OR RELATED TO THE SOFTWARE, INCLUDING INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF WE HAVE BEEN INFORMED OF THEIR POSSIBILITY IN ADVANCE.
+
+### Trademarks
+
+Except for displaying the License Details and identifying us as the origin of the Software, you have no right under these Terms and Conditions to use our trademarks, trade names, service marks or product names.
+
+## Grant of Future License
+
+We hereby irrevocably grant you an additional license to use the Software under the Apache License, Version 2.0 that is effective on the second anniversary of the date we make the Software available. On or after that date, you may use the Software under the Apache License, Version 2.0, in which case the following will apply:
+
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

modules/module-core/README.md

@@ -0,0 +1,3 @@
+# PowerSync Service Module Core
+
+Module which registers and configures basic core functionality for PowerSync services.

modules/module-core/package.json

@@ -0,0 +1,39 @@
+{
+  "name": "@powersync/service-module-core",
+  "repository": "https://github.com/powersync-ja/powersync-service",
+  "types": "dist/index.d.ts",
+  "version": "0.0.0",
+  "main": "dist/index.js",
+  "license": "FSL-1.1-Apache-2.0",
+  "type": "module",
+  "publishConfig": {
+    "access": "public"
+  },
+  "scripts": {
+    "build": "tsc -b",
+    "build:tests": "tsc -b test/tsconfig.json",
+    "clean": "rm -rf ./dist && tsc -b --clean",
+    "test": "vitest"
+  },
+  "exports": {
+    ".": {
+      "import": "./dist/index.js",
+      "require": "./dist/index.js",
+      "default": "./dist/index.js"
+    },
+    "./types": {
+      "import": "./dist/types/types.js",
+      "require": "./dist/types/types.js",
+      "default": "./dist/types/types.js"
+    }
+  },
+  "dependencies": {
+    "@powersync/lib-services-framework": "workspace:*",
+    "@powersync/service-core": "workspace:*",
+    "@powersync/service-rsocket-router": "workspace:*",
+    "@powersync/service-types": "workspace:*",
+    "fastify": "4.23.2",
+    "@fastify/cors": "8.4.1"
+  },
+  "devDependencies": {}
+}

modules/module-core/src/CoreModule.ts

@@ -0,0 +1,178 @@
+import cors from '@fastify/cors';
+import * as framework from '@powersync/lib-services-framework';
+import * as core from '@powersync/service-core';
+import { ReactiveSocketRouter } from '@powersync/service-rsocket-router';
+import fastify from 'fastify';
+
+export class CoreModule extends core.modules.AbstractModule {
+  constructor() {
+    super({
+      name: 'Core'
+    });
+  }
+
+  public async initialize(context: core.ServiceContextContainer): Promise<void> {
+    this.configureTags(context);
+
+    if ([core.system.ServiceContextMode.API, core.system.ServiceContextMode.UNIFIED].includes(context.serviceMode)) {
+      // Service should include API routes
+      this.registerAPIRoutes(context);
+    }
+
+    // Configures a Fastify server and RSocket server
+    this.configureRouterImplementation(context);
+
+    // Configures health check probes based off configuration
+    this.configureHealthChecks(context);
+
+    await this.configureMetrics(context);
+  }
+
+  protected configureTags(context: core.ServiceContextContainer) {
+    core.utils.setTags(context.configuration.metadata);
+  }
+
+  protected registerAPIRoutes(context: core.ServiceContextContainer) {
+    context.routerEngine.registerRoutes({
+      api_routes: [
+        ...core.routes.endpoints.ADMIN_ROUTES,
+        ...core.routes.endpoints.CHECKPOINT_ROUTES,
+        ...core.routes.endpoints.SYNC_RULES_ROUTES
+      ],
+      stream_routes: [...core.routes.endpoints.SYNC_STREAM_ROUTES],
+      socket_routes: [core.routes.endpoints.syncStreamReactive]
+    });
+  }
+
+  /**
+   * Configures the HTTP server which will handle routes once the router engine is started
+   */
+  protected configureRouterImplementation(context: core.ServiceContextContainer) {
+    context.lifeCycleEngine.withLifecycle(context.routerEngine, {
+      start: async (routerEngine) => {
+        // The router engine will only start servers if routes have been registered
+        await routerEngine.start(async (routes) => {
+          const server = fastify.fastify();
+
+          server.register(cors, {
+            origin: '*',
+            allowedHeaders: ['Content-Type', 'Authorization', 'User-Agent', 'X-User-Agent'],
+            exposedHeaders: ['Content-Type'],
+            // Cache time for preflight response
+            maxAge: 3600
+          });
+
+          core.routes.configureFastifyServer(server, {
+            service_context: context,
+            routes: {
+              api: { routes: routes.api_routes },
+              sync_stream: {
+                routes: routes.stream_routes,
+                queue_options: {
+                  concurrency: context.configuration.api_parameters.max_concurrent_connections,
+                  max_queue_depth: 0
+                }
+              }
+            }
+          });
+
+          const socketRouter = new ReactiveSocketRouter<core.routes.Context>({
+            max_concurrent_connections: context.configuration.api_parameters.max_concurrent_connections
+          });
+
+          core.routes.configureRSocket(socketRouter, {
+            server: server.server,
+            service_context: context,
+            route_generators: routes.socket_routes
+          });
+
+          const { port } = context.configuration;
+
+          await server.listen({
+            host: '0.0.0.0',
+            port
+          });
+
+          framework.logger.info(`Running on port ${port}`);
+
+          return {
+            onShutdown: async () => {
+              framework.logger.info('Shutting down HTTP server...');
+              await server.close();
+              framework.logger.info('HTTP server stopped');
+            }
+          };
+        });
+      }
+    });
+  }
+
+  protected configureHealthChecks(context: core.ServiceContextContainer) {
+    const {
+      configuration: {
+        healthcheck: { probes }
+      }
+    } = context;
+
+    const exposesAPI = [core.system.ServiceContextMode.API, core.system.ServiceContextMode.UNIFIED].includes(
+      context.serviceMode
+    );
+
+    if (context.serviceMode == core.system.ServiceContextMode.API) {
+      /**
+       * In the pure API mode we don't currently have any other code which touches the probes.
+       * This configures a timer which will touch every 5 seconds.
+       */
+      let timer: NodeJS.Timeout | null = null;
+      context.lifeCycleEngine.withLifecycle(null, {
+        start: () => {
+          setInterval(() => {
+            context
+              .get<framework.ProbeModule>(framework.ContainerImplementation.PROBES)
+              .touch()
+              .catch((ex) => this.logger.error(`Caught error while updating liveness probe: ${ex}`));
+          }, 5_000);
+        },
+        stop: () => {
+          if (timer) {
+            clearInterval(timer);
+            timer = null;
+          }
+        }
+      });
+    }
+
+    /**
+     * Maintains backwards compatibility if LEGACY_DEFAULT is present by:
+     *  - Enabling HTTP probes if the service started in API or UNIFIED mode
+     *  - Always enabling filesystem probes always exposing HTTP probes
+     * Probe types must explicitly be selected if not using LEGACY_DEFAULT
+     */
+    if (probes.use_http || (exposesAPI && probes.use_legacy)) {
+      context.routerEngine.registerRoutes({
+        api_routes: core.routes.endpoints.PROBES_ROUTES
+      });
+    }
+
+    if (probes.use_legacy || probes.use_filesystem) {
+      context.register(framework.ContainerImplementation.PROBES, framework.createFSProbe());
+    }
+  }
+
+  protected async configureMetrics(context: core.ServiceContextContainer) {
+    const apiMetrics = [core.metrics.MetricModes.API];
+    const streamMetrics = [core.metrics.MetricModes.REPLICATION, core.metrics.MetricModes.STORAGE];
+    const metricsModeMap: Partial<Record<core.system.ServiceContextMode, core.metrics.MetricModes[]>> = {
+      [core.system.ServiceContextMode.API]: apiMetrics,
+      [core.system.ServiceContextMode.SYNC]: streamMetrics,
+      [core.system.ServiceContextMode.UNIFIED]: [...apiMetrics, ...streamMetrics]
+    };
+
+    await core.metrics.registerMetrics({
+      service_context: context,
+      modes: metricsModeMap[context.serviceMode] ?? []
+    });
+  }
+
+  public async teardown(options: core.modules.TearDownOptions): Promise<void> {}
+}

modules/module-core/src/index.ts

@@ -0,0 +1 @@
+export * from './CoreModule.js';

modules/module-core/src/types/types.ts

@@ -0,0 +1 @@
+// No types for this module yet