Category: DigitalOcean

Golang and MySQL – DigitalOcean managed cluster

Hey everyone,

Just sharing a helper function to get you started when trying to connect to a mysql managed cluster on DigitalOcean with Golang.

Before we get into the code you’ll need to grab a couple of things from the database dashboard (on DigitalOcean).

  • Open the databases tab
  • Look for the “Connection Details” section
  • Download your ca cert file
  • Copy down your “public network” settings
    • If you’re moving this into a cluster you can use the “private network” settings instead
// initDb creates initialises the connection to mysql
func initDb(connectionString string, caCertPath string) (*sql.DB, error) {

	log.Infof("initialising db connection")

	// Prepare ssl if required: https://stackoverflow.com/a/54189333/522859
	if caCertPath != "" {

		log.Infof("Loading the ca-cert: %v", caCertPath)

		// Load the CA cert
		certBytes, err := ioutil.ReadFile(caCertPath)
		if err != nil {
			log.Fatal("unable to read in the cert file", err)
		}

		caCertPool := x509.NewCertPool()
		if ok := caCertPool.AppendCertsFromPEM(certBytes); !ok {
			log.Fatal("failed-to-parse-sql-ca", err)
		}

		tlsConfig := &tls.Config{
			InsecureSkipVerify: false,
			RootCAs:            caCertPool,
		}

		mysql.RegisterTLSConfig("bbs-tls", tlsConfig)
	}

	var sqlDb, err = sql.Open("mysql", connectionString)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to the database: %v", err)
	}

	// Ensure that the database can be reached
	err = sqlDb.Ping()
	if err != nil {
		return nil, fmt.Errorf("error on opening database connection: %s", err.Error())
	}

	return sqlDb, nil
}

A couple of things to note in the helper above.

  1. You’ll need to provide the path to your downloaded ca-cert as the second argument
  2. Your connection string will need to look something like the following: USERNAME:PASSWORD@tcp(HOST_NAME:PORT_NUMBER)/DB_NAME

Note that the “tcp(…)” bit is required, see the following post for more info: https://whatibroke.com/2021/11/27/failed-to-connect-to-the-database-default-addr-for-network-unknown-mysql-and-golang/

Depending on which version of the mysql driver you’re using you may also need to revert to the legacy auth mechanism: https://docs.digitalocean.com/products/databases/mysql/resources/troubleshoot-connections/#authentication

failed to connect to the database: default addr for network unknown – MySql and Golang

Hey everyone,

I’m currently setting up a mysql database on DigitalOcean and hit the following error when connecting:

failed to connect to the database: default addr for "DATABASE_CONN_STR" network unknown

Luckily this turned out to be a pretty easy fix. In the mysql driver repo you can see that the only scenario where this error is shown is when the network doesn’t match “tcp” or “unix”. 

// Set default network if empty
	if cfg.Net == "" {
		cfg.Net = "tcp"
	}

	// Set default address if empty
	if cfg.Addr == "" {
		switch cfg.Net {
		case "tcp":
			cfg.Addr = "127.0.0.1:3306"
		case "unix":
			cfg.Addr = "/tmp/mysql.sock"
		default:
			return errors.New("default addr for network '" + cfg.Net + "' unknown")
		}

	} else if cfg.Net == "tcp" {
		cfg.Addr = ensureHavePort(cfg.Addr)
	}

To fix it, all that was required was to wrap part of the connection string in tcp or unix. 

root:password@db-mysite.com:1234/db_name?ssl-mode=required&timeout=10s
root:password@tcp(db-mysite.com:1234)/db_name?ssl-mode=required&timeout=10s

Note that the host name and port on the second line is now wrapped in “tcp(…)”. In my case I didn’t have either set so I find it a bit strange that the “set default address if empty” check was triggered.

Thanks to this stackoverflow post and github link for the info:

No matches for kind “Deployment” in version “apps/v1beta2” – DigitalOcean

Hey everyone,

I’ve been working on a small golang app and decided to try out Kubernetes on DigitalOcean instead of the usual Azure or AWS. In order to get started I followed the tutorial at this link: https://www.digitalocean.com/community/tutorials/webinar-series-a-closer-look-at-kubernetes

I ran into a small issue while trying to using the provided deployment.yaml. 

error: unable to recognize "./api/deploy/prod/deployment.yaml": no matches for kind "Deployment" in version "apps/v1beta2"

This turned out to be an issue with the apiVersion being used. Changing the first line to apps/v1 resolved it:

apiVersion: apps/v1beta2
kind: Deployment
metadata:

apiVersion: apps/v1
kind: Deployment
metadata:

Thanks to this link on github for pointing me in the right direction: https://github.com/coreos/etcd-operator/issues/2126