Implementing TLS and mTLS

openssl req -x509 -newkey rsa:2048 -nodes -days 365 \
  -subj "/CN=localhost" -keyout server.key -out server.crt

cert, err := tls.LoadX509KeyPair("server.crt", "server.key")
if err != nil { log.Fatal(err) }

tlsCfg := &tls.Config{
    Certificates: []tls.Certificate{cert},
    MinVersion:   tls.VersionTLS13,
}
srv := grpc.NewServer(grpc.Creds(credentials.NewTLS(tlsCfg)))

creds := credentials.NewTLS(&tls.Config{
    ServerName: "users.internal",
    MinVersion: tls.VersionTLS13,
})
conn, _ := grpc.NewClient(addr, grpc.WithTransportCredentials(creds))

pool, _ := x509.SystemCertPool()
caPEM, _ := os.ReadFile("ca.crt")
pool.AppendCertsFromPEM(caPEM)
tlsCfg := &tls.Config{RootCAs: pool}

caPEM, _ := os.ReadFile("ca.crt")
pool := x509.NewCertPool()
pool.AppendCertsFromPEM(caPEM)
tlsCfg := &tls.Config{
    Certificates: []tls.Certificate{cert},
    ClientCAs:    pool,
    ClientAuth:   tls.RequireAndVerifyClientCert,
    MinVersion:   tls.VersionTLS13,
}