How to use TLS authentication with multiple hosts in connection url?

[Sireax]

Greetings! I was trying to authenticate to a postgres cluster using tls, but ran into a problem with specifying ServerName in tls.Config.

Here is how I create connection:

conf, err := pgx.ParseConfig(conn)
if err != nil {
    return nil, err
}
cert, err := tls.X509KeyPair(c.TLSCert, c.TLSKey)
if err != nil {
    return nil, err
}
tlsConfig = &tls.Config{
    ServerName:   connUrl.Hostname(),
    Certificates: []tls.Certificate{cert},
}
conf.TLSConfig = tlsAuth

This code works only if I connect to a single node. If the connection url looks something like postgres://pg1:5432,pg2:5432/database it refuses server certificate.

The problem is that we can only specify one hostname in tls.ServerName field. In source files of x509 package there is not support for multiple hosts, separated for example by comma (or is there?).

So the question is - how can I authenticate to postgres using tls if the connection url consists of 2+ hostnames?

There is also a problem with calling url.Hostname() method, as it just separates host and port by colon. I can easily write a helper method to return correct hostnames like pg1,pg2. But anyway ServerName will not work correctly with this format

[jackc]

Multiple hosts get converted to fallback configs. See https://pkg.go.dev/github.com/jackc/pgx/v5@v5.3.1/pgconn#FallbackConfig. You can specify different tsl configs for each.

[Sireax]

So I just specify ServerName like pghost1,pghost2, or where should I provide multiple tls configs?
Could you please provide a basic example of doing that?

[jackc]

You would need to iterate through the fallback configs and set the tls config option appropriately for each one.

[Sireax]

Got it, thanks!