Strongloop app does not load local datasource

Question

I want to use different environment specific datasource configurations in a Strongloop app. I saw at https://docs.strongloop.com/display/public/LB/Environment-specific+configuration that the priority of configurations are:

1. Environment-specific configuration, based on the value of NODE_ENV; for example, server/config.staging.json.
2. Local configuration file; for example, server/config.local.json.
3. Default configuration file; for example, server/config.json.

I have declared three datasource conf files: datasources.json:

{}

datasources.local.json:

{
  "db": {
    "name": "db",
    "connector": "loopback-connector-mongodb",
    "host":"127.0.0.1",
    "port": "27017",
    "database": "woowDev"
  }
}

and datasources.staging.js:

module.exports = {
  db: {
    connector: 'mongodb',
    hostname: process.env.OPENSHIFT_MONGODB_DB_HOST,
    port: process.env.OPENSHIFT_MONGODB_DB_PORT,
    user: process.env.OPENSHIFT_MONGODB_DB_USERNAME,
    password: process.env.OPENSHIFT_MONGODB_DB_PASSWORD,
    database: 'woow'
  }
};

Now unless I put the configuration of datasources.local.json in datasources.json it does not work. I keep getting the error: AssertionError: User is referencing a dataSource that does not exist: "db"

I tried also to add the local conf to staging conf and defined the variable NODE_ENV, but it would not load neither datasource.staging.js. I defined the NODE_ENV by doing:

export NODE_ENV=staging

Soot

Hmm... what if you delete the otherwise empty datasources.json file? – Lynelllynelle

tried, does not work, what else can I try? – Soot

Is it possible that your current environment is in fact staging? I see that your staging datasource config file does not have a name property in the definition. It would need this regardless. – Lynelllynelle

Oh, and the connector should just be mongodb, I think. – Lynelllynelle

No, I tried to add the local conf to staging conf and defined the variable NODE_ENV, but it would not load neither datasource.staging.js – Soot

try to remove "module.exports = " from your datasoruces.staging.json – Waldowaldon

Are you sure? it is a javascript file not json – Soot

No, sorry misread the question. – Waldowaldon

Answer 1

I used node-debug to track down the issue. And it came in this particular source strongloop file:

node_modules/loopback-boot/lib/config-loader.js

the function:

function mergeDataSourceConfig(target, config, fileName) {
  for (var ds in target) {
    var err = applyCustomConfig(target[ds], config[ds]);
    if (err) {
      throw new Error('Cannot apply ' + fileName + ' to `'  + ds + '`: ' + err);
    }
  }
}

will not merge configs if "db" key is not defined in the master file i.e. datasources.json.

So, I just modified the datasources.json to:

{
  "db": {}
}

and it worked!

Maybe it is my fault but the documentation is not clear enough.

Soot

It is not really obvious the way it is written in the documentation, but indeed you can only override parameters, not create them in alternative configs You can **override** values that are **set** in config.json in: config.local.js or config.local.json config.env.js or config.env.json, where env is the value of NODE_ENV – Odericus

I'm not so sure that this is exactly the case - I specify a port in config.local.js but not in config.json and the app starts on the expected port. – Maddis

Answer 2

Trick is to add all the datasources(memory/redis/mongo/postgres) in datasources.json and then override parameters in datasources.local.js or datasources.staging.js or datasources.production.js

Sample file configuration:

datasources.json

{
  "db": {
    "name": "db",
    "connector": "memory"
  },
  "redisDS": {
    "name": "redisDS",
    "connector": "redis"
  },
  "testPostgress": {
    "port": 5432,
    "name": "localPostgress",
    "user": "akumar",
    "connector": "postgresql"
  }
}

datasources.staging.js

module.exports = {
  db:{
    connector: 'memory'
  },
  redisDS:{
    connector: 'redis'
  },
  testPostgress:{
    database:'stagingPostgress'
  }
};

Loopback will override database name in this case similarly you can override other datasource parameters like port and user

Tubulate