Nodejs with molecular micro services application, how to keep running server

Question

I am using NodeJS with Molecular, using "npm run dev" to run the application. When the console closes the application is getting down, how to run the application as background service, while in NodeJS I use "Forever" module, can i use it or any other module to run the application.

Thanks in advance

I had found the solution, added below commands in scripts of package.json fixed the issue.

"start": "forever start --minUptime 1000 --spinSleepTime 1000 ./node_modules/.bin/moleculer-runner --instances=max services",

"stop": "forever stop ./node_modules/.bin/moleculer-runner",

Answer 1

docker is nice, but could be overcomplicated in some cases. you can just install pm2

npm install pm2 -g

then

pm2 start app.js

to start app and you can start many of them..

pm2 list

view started apps

pm2 save

save list

pm2 startup

ensure it will start your app(s) after reboot

Answer 2

Assuming you have all the services (can be one or many) inside a services directory.

Create a Moleculer Runner helper script that will help in running the application as Moleculer Project.

• Create a moleculer.config.js and place it insode root directory of your application.
• In package.json file add scripts
  • "dev": "moleculer-runner --repl --hot services/**/*.service.js"
  • "start": "moleculer-runner --instances=max services"

---

Sample moleculer.config.js :

"use strict";

module.exports = {
  // Namespace of nodes to segment your nodes on the same network.
  namespace: "MyMicroService",
  // Unique node identifier. Must be unique in a namespace.
  nodeID: "node@my-machine",
  // Custom metadata store. Store here what you want. Accessing: `this.broker.metadata`
  metadata: {},

  // Enable/disable logging or use custom logger. More info: https://moleculer.services/docs/0.14/logging.html
  // Available logger types: "Console", "File", "Pino", "Winston", "Bunyan", "debug", "Log4js", "Datadog"
  logger: {
    type: "Console",
    options: {
      // Using colors on the output
      colors: true,
      // Print module names with different colors (like docker-compose for containers)
      moduleColors: false,
      // Line formatter. It can be "json", "short", "simple", "full", a `Function` or a template string like "{timestamp} {level} {nodeID}/{mod}: {msg}"
      formatter: "full",
      // Custom object printer. If not defined, it uses the `util.inspect` method.
      objectPrinter: null,
      // Auto-padding the module name in order to messages begin at the same column.
      autoPadding: false,
    },
  },
  // Default log level for built-in console logger. It can be overwritten in logger options above.
  // Available values: trace, debug, info, warn, error, fatal
  logLevel: "info",

  // Define transporter.
  // More info: https://moleculer.services/docs/0.14/networking.html
  // Note: During the development, you don't need to define it because all services will be loaded locally.
  // In production you can set it via `TRANSPORTER=nats://localhost:4222` environment variable.
  transporter: null, //"NATS"
  //   transporter: "NATS", //"null"

  // Define a cacher.
  // More info: https://moleculer.services/docs/0.14/caching.html
  cacher: null,

  // Define a serializer.
  // Available values: "JSON", "Avro", "ProtoBuf", "MsgPack", "Notepack", "Thrift".
  // More info: https://moleculer.services/docs/0.14/networking.html#Serialization
  serializer: "JSON",

  // Number of milliseconds to wait before reject a request with a RequestTimeout error. Disabled: 0
  requestTimeout: 10 * 1000,

  // Retry policy settings. More info: https://moleculer.services/docs/0.14/fault-tolerance.html#Retry
  retryPolicy: {
    // Enable feature
    enabled: false,
    // Count of retries
    retries: 5,
    // First delay in milliseconds.
    delay: 100,
    // Maximum delay in milliseconds.
    maxDelay: 1000,
    // Backoff factor for delay. 2 means exponential backoff.
    factor: 2,
    // A function to check failed requests.
    check: (err) => err && !!err.retryable,
  },

  // Limit of calling level. If it reaches the limit, broker will throw an MaxCallLevelError error. (Infinite loop protection)
  maxCallLevel: 100,

  // Number of seconds to send heartbeat packet to other nodes.
  heartbeatInterval: 10,
  // Number of seconds to wait before setting node to unavailable status.
  heartbeatTimeout: 30,

  // Cloning the params of context if enabled. High performance impact, use it with caution!
  contextParamsCloning: false,

  // Tracking requests and waiting for running requests before shuting down. More info: https://moleculer.services/docs/0.14/context.html#Context-tracking
  tracking: {
    // Enable feature
    enabled: false,
    // Number of milliseconds to wait before shuting down the process.
    shutdownTimeout: 5000,
  },

  // Disable built-in request & emit balancer. (Transporter must support it, as well.). More info: https://moleculer.services/docs/0.14/networking.html#Disabled-balancer
  disableBalancer: false,

  // Settings of Service Registry. More info: https://moleculer.services/docs/0.14/registry.html
  registry: {
    // Define balancing strategy. More info: https://moleculer.services/docs/0.14/balancing.html
    // Available values: "RoundRobin", "Random", "CpuUsage", "Latency", "Shard"
    strategy: "RoundRobin",
    // Enable local action call preferring. Always call the local action instance if available.
    preferLocal: true,
  },

  // Settings of Circuit Breaker. More info: https://moleculer.services/docs/0.14/fault-tolerance.html#Circuit-Breaker
  circuitBreaker: {
    // Enable feature
    enabled: false,
    // Threshold value. 0.5 means that 50% should be failed for tripping.
    threshold: 0.5,
    // Minimum request count. Below it, CB does not trip.
    minRequestCount: 20,
    // Number of seconds for time window.
    windowTime: 60,
    // Number of milliseconds to switch from open to half-open state
    halfOpenTime: 10 * 1000,
    // A function to check failed requests.
    check: (err) => err && err.code >= 500,
  },

  // Settings of bulkhead feature. More info: https://moleculer.services/docs/0.14/fault-tolerance.html#Bulkhead
  bulkhead: {
    // Enable feature.
    enabled: false,
    // Maximum concurrent executions.
    concurrency: 10,
    // Maximum size of queue
    maxQueueSize: 100,
  },

  // Enable action & event parameter validation. More info: https://moleculer.services/docs/0.14/validating.html
  validator: true,

  errorHandler: null,

  // Enable/disable built-in metrics function. More info: https://moleculer.services/docs/0.14/metrics.html
  metrics: {
    enabled: false,
    // Available built-in reporters: "Console", "CSV", "Event", "Prometheus", "Datadog", "StatsD"
    reporter: {
      type: "Prometheus",
      options: {
        // HTTP port
        port: 3030,
        // HTTP URL path
        path: "/metrics",
        // Default labels which are appended to all metrics labels
        defaultLabels: (registry) => ({
          namespace: registry.broker.namespace,
          nodeID: registry.broker.nodeID,
        }),
      },
    },
  },

  // Enable built-in tracing function. More info: https://moleculer.services/docs/0.14/tracing.html
  tracing: {
    enabled: false,
    // Available built-in exporters: "Console", "Datadog", "Event", "EventLegacy", "Jaeger", "Zipkin"
    exporter: {
      type: "Console", // Console exporter is only for development!
      options: {
        // Custom logger
        logger: null,
        // Using colors
        colors: true,
        // Width of row
        width: 100,
        // Gauge width in the row
        gaugeWidth: 40,
      },
    },
  },

  // Register custom middlewares
  middlewares: [],

  // Register custom REPL commands.
  replCommands: null,

  // Called after broker created.
  created(broker) {},

  // Called after broker started.
  async started(broker) {},

  // Called after broker stopped.
  async stopped(broker) {},
};

Answer 3

You can run your project as a daemon docker container