In this recipe, we compress the source code directory into archive.tar.gz. We create a file with File::create("archive.tar.gz") and assign it to the tar_gz variable. We then wrap it using flate2::write::GzEncoder and tar::Builder. Lastly, we add the contents of the ../sample_com directory recursively into the archive under ./backup with Builder::append_dir_all.

The error-chain crate is a library for consistent and reliable error handling that makes it easier to take full advantage of Rust's powerful error-handling features, without the overhead of maintaining boilerplate error types and conversions. It implements a strategy for defining your own error types, as well as conversions from others' error types.

The basic pattern we use here has a function named run() that produces a Result that acts like a real main function. We use the error-chain crate to make ? work within run. This is using the error_chain! macro from the error-chain to define a custom Error and Result type, along with automatic conversions from the crate error types. The automatic conversions make the ? operator work. The quick_main! macro generates the actual main function and prints out the error if it occurs during the course of execution.

We return Ok(()) to the quick_run! macro to ensure that the program executed successfully without any errors.