nodejs + azure 函数应用程序 - 处理数据库连接的最佳实践？

Question

Please point me to the right forum if this is not the place to ask this (apologies in advance).

I mainly want to know if, in a nodejs app, instantiating a brand new db connection inside an azure function app and then closing it each time when the function app exits, is a bad idea. (feels like a bad idea).

Is this standard practice, or is there a better way for keeping a connection alive across invocations of serverless functions? Or does this not matter?

The connection in question will be at best a mongodb-native driver connection or mongoose connection talking to a cosmosdb instance.

Answer 1

Creating a new database connection every time can led to poor performance performance. you can add a global pointer to a Database client to retain the connection. Something as shown below:

const mongodb = require('mongodb');

const uri = 'mongodb+srv://XYZ/test';

let client = null;

module.exports = function (context, req) {
  context.log('Running');

  let hasClient = client != null;

  if (client == null) {
    mongodb.MongoClient.connect(uri, function(error, _client) {
      if (error) {
        context.log('Failed to connect');
        context.res = { status: 500, body: res.stack }
        return context.done();
      }
      client = _client;
      context.log('Connected');
      query();
    });
  } else {
    query();
  }

  function query() {
    client.db('test').collection('tests').find().toArray(function(error, docs) {
      if (error) {
        context.log('Error running query');
        context.res = { status: 500, body: res.stack }
        return context.done();
      }

      context.log('Success!');
      context.res = {
        headers: { 'Content-Type': 'application/json' },
        body: 'Document Length ' + docs.length + ', Connection reused ' + hasClient
      };
      context.done();     
    });
  }
};