krunvm 0.1.6

Create microVMs from OCI images
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// Copyright 2021 Red Hat, Inc.
// SPDX-License-Identifier: Apache-2.0

use std::fs;
use std::io::Write;
use std::process::Command;

use super::utils::{
    get_buildah_args, mount_container, parse_mapped_ports, parse_mapped_volumes, umount_container,
    BuildahCommand,
};
use crate::{ArgMatches, KrunvmConfig, VmConfig, APP_NAME};

fn fix_resolv_conf(rootfs: &str, dns: &str) -> Result<(), std::io::Error> {
    let resolvconf_dir = format!("{}/etc/", rootfs);
    fs::create_dir_all(resolvconf_dir)?;
    let resolvconf = format!("{}/etc/resolv.conf", rootfs);
    let mut file = fs::File::create(resolvconf)?;
    file.write_all(b"options use-vc\nnameserver ")?;
    file.write_all(dns.as_bytes())?;
    file.write_all(b"\n")?;
    Ok(())
}

pub fn create(cfg: &mut KrunvmConfig, matches: &ArgMatches) {
    let cpus = match matches.value_of("cpus") {
        Some(c) => match c.parse::<u32>() {
            Err(_) => {
                println!("Invalid value for \"cpus\"");
                std::process::exit(-1);
            }
            Ok(cpus) => cpus,
        },
        None => cfg.default_cpus,
    };
    let mem = match matches.value_of("mem") {
        Some(m) => match m.parse::<u32>() {
            Err(_) => {
                println!("Invalid value for \"mem\"");
                std::process::exit(-1);
            }
            Ok(mem) => mem,
        },
        None => cfg.default_mem,
    };
    let dns = match matches.value_of("dns") {
        Some(d) => d,
        None => &cfg.default_dns,
    };

    let workdir = matches.value_of("workdir").unwrap();

    let volume_matches = if matches.is_present("volume") {
        matches.values_of("volume").unwrap().collect()
    } else {
        vec![]
    };
    let mapped_volumes = parse_mapped_volumes(volume_matches);

    let port_matches = if matches.is_present("port") {
        matches.values_of("port").unwrap().collect()
    } else {
        vec![]
    };
    let mapped_ports = parse_mapped_ports(port_matches);

    let image = matches.value_of("IMAGE").unwrap();

    let name = matches.value_of("name");
    if let Some(name) = name {
        if cfg.vmconfig_map.contains_key(name) {
            println!("A VM with this name already exists");
            std::process::exit(-1);
        }
    }

    let mut args = get_buildah_args(cfg, BuildahCommand::From);
    args.push(image.to_string());

    let output = match Command::new("buildah")
        .args(&args)
        .stderr(std::process::Stdio::inherit())
        .output()
    {
        Ok(output) => output,
        Err(err) => {
            if err.kind() == std::io::ErrorKind::NotFound {
                println!("{} requires buildah to manage the OCI images, and it wasn't found on this system.", APP_NAME);
            } else {
                println!("Error executing buildah: {}", err);
            }
            std::process::exit(-1);
        }
    };

    let exit_code = output.status.code().unwrap_or(-1);
    if exit_code != 0 {
        println!(
            "buildah returned an error: {}",
            std::str::from_utf8(&output.stdout).unwrap()
        );
        std::process::exit(-1);
    }

    let container = std::str::from_utf8(&output.stdout).unwrap().trim();
    let name = if let Some(name) = name {
        name.to_string()
    } else {
        container.to_string()
    };
    let vmcfg = VmConfig {
        name: name.clone(),
        cpus,
        mem,
        dns: dns.to_string(),
        container: container.to_string(),
        workdir: workdir.to_string(),
        mapped_volumes,
        mapped_ports,
    };

    let rootfs = mount_container(cfg, &vmcfg).unwrap();
    fix_resolv_conf(&rootfs, dns).unwrap();
    umount_container(cfg, &vmcfg).unwrap();

    cfg.vmconfig_map.insert(name.clone(), vmcfg);
    confy::store(APP_NAME, cfg).unwrap();

    println!("microVM created with name: {}", name);
}