How to reference database properties using Digital Ocean bindable variables? - node.js

Question

Using DigitalOcean's managed Postgres database cluster and App Platform, I want to connect my NodeJS app to my Postgres database.
At the moment, I'm getting the time out error below. As part of debugging the misconfiguration, I want to verify that I'm using the bindable app environment variables correctly.
Here are some basic details. Using this information, can you help me to understand how to construct the bindable variable?
Database Cluster Name: demo
Database Pool Name: Demo
Example database Name: defaultdb
App Platform > App Name: demo1
I've tried an assortment of combinations as shown below. When I run the echo $MY_VAR command, none of these values are interpolated. I see the bindable variable syntax.
# Test using database cluster name only.
apps#client:~$ echo $TEST1
${demo.HOSTNAME}
# Test using _self, or the current context. I believe this is the app context.
apps#client:~$ echo $TEST2
${_self.HOSTNAME}
# Test using syntax of <db_cluster_name>.<db_pool_name>.<env_var>
apps#client:~$ echo $TEST3
${demo.Demo.HOSTNAME}
# Test using syntax of <app_name>.<db_pool_name>.<env_var>
apps#client:~$ echo $TEST4
${demo1.Demo.HOSTNAME}
Most of these are a bit ridiculous, and at this point, I'm just experimenting with various combinations. Can you please help me to understand the syntax that would output the database hostname when I run echo $DB_HOSTNAME from the Digital Ocean app console? Thank you.
Why am I trying to confirm the bindable variable syntax?
I'd like to use the app environment variables for databases. Because of the connection refused, I believe the issue might be related to the CA certificate not being available as part of the Postgres connection details. Since my syntax isn't resolving, the CA cert isn't available when connecting to Postgres in my code.
The bindable variables should be populated in Node's environment variables and available through process.env.
# Sample postgres configuration
const postgresConfig = {
user: process.env.PG_USER,
password: process.env.PG_PASSWORD,
host: process.env.PG_HOST,
database: process.env.PG_DATABASE,
port: process.env.PG_PORT,
ssl: {
require: true,
rejectUnauthorized: true,
ca: process.env.PG_CA_CERT,
},
};
Error message
When attempting to run a Postgres query, I get this error:
Error: connect ETIMEDOUT 10.x.y.z:25061
at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1278:16) {
errno: -110,
code: 'ETIMEDOUT',
syscall: 'connect',
address: '10.x.y.x',
port: 25061
}

Answer 1

I see how it works now. When you are managing your App Platform application, under the Create menu button is the option to "Create/Attach Database".
I didn't look here because I didn't think I would need to use the "Create" button to attach an existing database. It would be more intuitive to find this feature under the "Actions" menu. I fell victim to some peculiar UI design decisions.
Once the database is attached, all is well in the world.