Cargo.toml

[package]
name = "instant-replay"
version = "0.1.0"
authors = ["davidpdrsn"]

[dependencies]
postgres = { version = "0.15", features = ["with-openssl"] }

main.rs

extern crate postgres;

use postgres::{Connection, TlsMode};
use postgres::tls::openssl::OpenSsl;

fn main() {
    let openssl = OpenSsl::new().expect("failed to create openssl");

    let connection = Connection::connect(
        "postgres://_:_@_:5432/_?sslmode=require",
        TlsMode::Prefer(&openssl),
        ).expect("failed to connect");

    for row in &connection.query("select * from users limit 1", &[]).expect("query failed") {
        println!("{:?}", row);
    }
}

The error I get is:

thread 'main' panicked at 'failed to connect: Error(Tls(Failure(MidHandshakeSslStream { stream: SslStream { stream: TcpStream { addr: V4(192.168.1.12:51332), peer: V4(54.228.220.197:5432), fd: 5 }, ssl: Ssl { state: "error", verify_result: X509VerifyError { code: 18, error: "self signed certificate" } } }, error: Ssl(ErrorStack([Error { code: 337047686, library: "SSL routines", function: "tls_process_server_certificate", reason: "certificate verify failed", file: "ssl/statem/statem_clnt.c", line: 1230 }])) })))', src/libcore/result.rs:859
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
   1: std::panicking::default_hook::{{closure}}
   2: std::panicking::default_hook
   3: std::panicking::rust_panic_with_hook
   4: std::panicking::begin_panic
   5: std::panicking::begin_panic_fmt
   6: rust_begin_unwind
   7: core::panicking::panic_fmt
   8: core::result::unwrap_failed
   9: <core::result::Result<T, E>>::expect
  10: run::main
  11: __rust_maybe_catch_panic
  12: std::rt::lang_start
  13: main