Zero To Production (with axum)

Developed following the book Zero To Production In Rust using axum.

A summary of the differences:

• §3.3: the chosen web framework is axum;
• §3.5: hyper is used as HTTP client;
• §3.8: docker compose is used to setting up the test environment:

  $ docker compose -f docker-compose.test.yml -p zero2prod up -d
  $ sqlx database reset -y

• §3.9: axum::State is used as type safe replacement of axum::Extension and ? operator is used to handle errors;
• §4.5: traces are collected using Grafana Tempo and they can be inspected using Grafana at the address http://localhost:3000;
• §5.3: hierarchical configuration is not implemented, configuration can be customized using environment variables; database migrations can be executed on service startup;
• §6.8: unmaintained project claim is replaced with claym;
• §6.10: error 422 Unprocessable Entity is used to notify a syntatically correct request, but semantically erroneous;
• §7.2: hyper is used as HTTP client, HTTP client timeout can be configured using humantime;
• §7.8: routes are refactored exploiting that Result implements IntoResponse.