Prerequisites

Before you connect, you need a Postgres to connect to. The cheapest debugger you’ll get on this whole journey is a Postgres that prints every byte it does back at you, so let’s run one of those.

A Postgres that talks back

Open a terminal, paste this, and leave it running. It’s a throwaway container — --rm means it disappears when you Ctrl-C, so nothing leaks past your tutorial session.

docker run --rm -it \
  --name babar-pg \
  -p 5432:5432 \
  -e POSTGRES_PASSWORD=postgres \
  postgres:17 \
  -c log_statement=all \
  -c log_min_duration_statement=0 \
  -c log_connections=on \
  -c log_disconnections=on

What each flag is doing for you:

• --rm -it — foreground, throwaway, Ctrl-C to stop. No daemon, no cleanup chores later.
• -p 5432:5432 — Postgres’ default port, exposed on localhost.
• -e POSTGRES_PASSWORD=postgres — sets the password for the default postgres superuser. The postgres:17 image already creates that role and a database of the same name on first boot, so we just need to give it a password.
• -c log_statement=all — every SQL statement gets logged.
• -c log_min_duration_statement=0 — every statement also gets a duration logged, no threshold.
• -c log_connections=on / -c log_disconnections=on — connection lifecycle in the same stream.

The connection string for everything that follows is:

postgres://postgres:postgres@localhost:5432/postgres

…which in Config form is:

#![allow(unused)]
fn main() {
use babar::Config;

let cfg = Config::new("localhost", 5432, "postgres", "postgres")  // type: Config
    .password("postgres")
    .application_name("first-query");
}

Why foreground?

Because the second window — the one tailing those logs — is where you’ll see exactly what babar sent on the wire. Prepared-statement names, parameter values, every BEGIN and COMMIT. When something surprises you in chapter 3 or chapter 7, your first move is to glance at that window. It is faster than any println you will ever write.

Stop it

Ctrl-C in the Postgres window. --rm cleans up the container; the data goes with it. That’s the point — every tutorial run is a fresh database.

Next

• Your first query → — connect, query, decode.