How to add custom certificate authority (CA) to Node.js?

To add custom certificate authority (CA) to Node.js, we call the options.ca.push method.

For instance, we write

const trustedCa = [
  "/etc/pki/tls/certs/ca-bundle.crt",
  "/path/to/custom/cert.crt",
];

https.globalAgent.options.ca = [];
for (const ca of trustedCa) {
  https.globalAgent.options.ca.push(fs.readFileSync(ca));
}

to loop through each trusrtedCa path with a for-of loop.

In it, we call https.globalAgent.options.ca.push with the file read from readFileSync to add the certificate file into the array with push.