Openwhisk failing to call compose postgre sql - node.js

Question

I have tried for more hours than I care to admit to get an openWhisk function to call a postgre sql datbase on Compose.io. Here is my code:
My latest incarnation is this:
function myAction(params) {
return new Promise(function(resolve, reject) {
console.log('Connecting to Compose database');
// console.log('Params ---> ', params);
var mysql = require('promise-mysql');
var fs = require('fs');
var pg = require('pg');
var request = require('request')
var Promise = require('promise/lib/es6-extensions');
var connString = "postgres:xxxx";
pg.connect(connString, function(err, client, done) {
console.log("connectiong..", err, client, done);
if (err) {
console.log('[connectToCompose] failed to fetch client from pool', err);
reject(err);
} else {
params.client = client; params.done = done;
console.log('[connectToCompose] obtained a Compose client');
return(params);
}
})
// params.client.done();
// console.log("closing connectiong");
})
}
exports.main = myAction;
I have a similar example where I connect to a different SQL database (not Compose) and use sql promise not postgre and it works. What am I doing wrong?

Answer 1

To work with OpenWhisk and any database offering, you need to use promisified JavaScript code; the event loop as it's used in ordinary nodejs isn't available. I have an example that uses pg-promise (taken more or less exactly from the project docs) and it works fine for me. Try something like this:
const promise = require('bluebird');
const initOptions = {
promiseLib: promise // overriding the default (ES6 Promise);
};
const pgp = require('pg-promise')(options);
const conn_info = {...connection info...};
const db = pgp(conn_info);
module.exports.main = function main(args) {
db.any('SELECT * FROM items')
.then(data => {
console.log('DATA:', data);
// return whatever data you wanted
resolve({message: 'success'});
})
.catch(error => {
console.log('ERROR:', error);
});
}
Not all of the dependencies here are available on OpenWhisk by default, so when you deploy the action, include both your *.js file and the whole of node_modules/ in a zip file, and upload that. It's definitely possible to use the Compose Postgres with OpenWhisk, if that helps to encourage you :)