Connection to Redis instance closed every couple of minutes - node.js

Question

I'm running a node.js on Google Cloud that uses a redis caching server. It was running fine for a couple of months but it suddenly started throwing connection errors and occasionally stops responding.
The app is running in the standard environment and connects to the VM that is running the Redis instance via a VPC connector. I suspect it is a networking issue because the issue doesn't seem to appear when I run the Node.js app from my own computer (connected to the same Redis server) or when the app is run in a flex environment and connects to the subnetwork directly. However, I'd prefer the app to run in the standard environment because as far as I know that's the only way to force the traffic over https.
When I monitor via Redis-cli the server just doesn't receive any commands when the connection has failed.
Time out in redis.conf is set to 0
Redis version: 5.0.5
Here's the Redis code. I don't think it is the issue though, it was running without issue a couple of weeks ago.
const redis = require('redis')
const redisOptions = {
host: process.env.REDIS_IP,
port: process.env.REDIS_PORT,
password: process.env.REDIS_PASS,
enable_offline_queue: false,
}
const client = redis.createClient(redisOptions.host, redisOptions.port)
// Log any errors
client.on('error', function(error) {
console.log('Error:')
console.log(error)
})
module.exports = client
These errors regularly show up in the Google App engine log. When they occur commands sent to Redis do not show up in in the logs.
A 2019-08-31T12:42:27.162834Z { Error: Redis connection to 10.128.15.197:6379 failed - read ETIMEDOUT "
A 2019-08-31T12:42:27.162868Z at TCP.onStreamRead (internal/stream_base_commons.js:111:27) errno: 'ETIMEDOUT', code: 'ETIMEDOUT', syscall: 'read' }

Answer 1

I see same issue many times with different databases. You already found the issue. Number of opened connections - is limited and costly resource. Try to use following pattern (it is just an example):
// Inside your db module
function dbCall(userFunc) {
const client = anyDb.createClient(host, port, ...);
userFunc(client, () => { client.quit(); /* client.close() or whatever */ }
}
// Usage
dbCall((client, done) => {
client.doSomethingWithCallback(..., () => {
// user code
done();
});
});
dbCall((client, done) => {
client.doSomePromise(...)
.finally(done);
});