how to use node pg in AWS Lambda? - node.js

Question

UPDATE/SOLVED ... the problem was that pgpass plugin was looking for $HOME/.pgpass, and $HOME wasn't defined on lambda, causing failure of join(undefined, '.pgpass'). Not really worth crediting myself with an answer for that ....
I have the following test code in a lambda handler (compiled from typescript):
const db = new Pool()
const {rows} = await db.query('select 1 as x')
console.log('rows', JSON.stringify(rows))
The connection is created via PGHOST PGPORT PGUSER PGDATABASE in the environment. I know the configuration is "almost right" because the first time I tried it I got:
{"errorMessage":"error: no pg_hba.conf entry for host \"10.1.1.249\",
user \"foo\", database \"bar\", SSL off\n at
Connection.parseE (/var/task/handler.js:9209:11)\n at
Connection.parseMessage (/var/task/handler.js:9034:19)\n at
Socket. (/var/task/handler.js:8777:22)\n at emitOne
(events.js:96:13)\n at Socket.emit (events.js:188:7)\n at
readableAddChunk (_stream_readable.js:176:18)\n at
Socket.Readable.push (_stream_readable.js:134:10)\n at TCP.onread
(net.js:547:20)"}
That seemed hopeful. I changed the postgres config to allow from the subnet, and tried again. However, now I get:
2018-02-06 18:14:21.183 (-05:00) 76761ca5-0b93-11e8-8783-a74d098c9f4a select
2018-02-06 18:14:21.202 (-05:00) 76761ca5-0b93-11e8-8783-a74d098c9f4a TypeError: Path must be a string. Received undefined
at assertPath (path.js:7:11)
at Object.join (path.js:1211:7)
at Object.module.exports.getFileName (/var/task/handler.js:32434:16)
at module.exports (/var/task/handler.js:32355:23)
at Connection.<anonymous> (/var/task/handler.js:31255:9)
at emitOne (events.js:96:13)
at Connection.emit (events.js:188:7)
at Socket.<anonymous> (/var/task/handler.js:8781:12)
at emitOne (events.js:96:13)
at Socket.emit (events.js:188:7)
END RequestId: 76761ca5-0b93-11e8-8783-a74d098c9f4a
What is going on? It seemed as if it had got to the database and connected the first time... Now it fails on the query. Is there some option I should be using?

Answer 1

First, you are not calling pool.connect to acquire a client from the pool.
Second, the current Node.js runtime 6.10 on AWS Lambda does not support async functions. (Unless you transpile your code down to ES5 using Babel directly or some other boilerplate that uses Babel such as es2017-lambda-boilerplate)
Having said that, you'll have to use either callbacks or promises (then/catch). For example:
const {Pool} = require("pg");
const db = new Pool({
host: "localhost",
user: "database-user",
// ... rest of config options
});
db.connect((err, client, release) => {
if (err) {
console.error("Error acquiring client.", err.stack);
} else {
client.query("SELECT 1 AS x", (err, result) => {
release();
if (err) {
console.error("Error executing query.", err.stack);
} else {
console.log(result.rows);
}
})
}
})