mocker.md

Preparation

First we will create a small program in Rust that will:

1. print its pid
2. list all the files and directories in /

use std::{ fs, process };
fn main() {
    println!("{}", process::id());
    
    let paths = fs::read_dir("/").unwrap();

    for path in paths {
        println!("Name: {}", path.unwrap().path().display())
    }
}

We can now statically build this program: RUSTFLAGS='-C target-feature=+crt-static' cargo build --release --target x86_64-unknown-linux-gnu.

Exercice

Let's now create a new cargo project: cargo new mocker (mocker -> mock docker)

Let's build mocker a small docker clone interatively:

1. Make it so that mocker ./pid will run the binary and show its output.
2. Make it so that running mocker ./pid shows 1 as its pid

tip

When you execute the binary, give it a new pid namespace https://docs.rs/nix/0.26.2/nix/sched/struct.CloneFlags.html#associatedconstant.CLONE_NEWPID use namespaces

3. Make it so that running mocker ./pid will make pid list files from the current directory

Tip

Use chroot: https://docs.rs/nix/0.26.2/nix/unistd/fn.chroot.html