Merge pull request #36 from slp/macos-rosetta

macos: add support for running x86 microVMs on ARM64

Author: slp

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "krunvm"
-version = "0.2.2"
+version = "0.2.3"
 authors = ["Sergio Lopez <[email protected]>"]
 description = "Create microVMs from OCI images"
 repository = "https://github.com/containers/krunvm"

Cargo.toml

@@ -3,6 +3,8 @@
 
 use std::fs;
 use std::io::Write;
+#[cfg(target_os = "macos")]
+use std::path::Path;
 use std::process::Command;
 
 use super::utils::{
@@ -11,6 +13,9 @@ use super::utils::{
 };
 use crate::{ArgMatches, KrunvmConfig, VmConfig, APP_NAME};
 
+#[cfg(target_os = "macos")]
+const KRUNVM_ROSETTA_FILE: &str = ".krunvm-rosetta";
+
 fn fix_resolv_conf(rootfs: &str, dns: &str) -> Result<(), std::io::Error> {
     let resolvconf_dir = format!("{}/etc/", rootfs);
     fs::create_dir_all(resolvconf_dir)?;
@@ -62,7 +67,7 @@ fn export_container_config(
 }
 
 pub fn create(cfg: &mut KrunvmConfig, matches: &ArgMatches) {
-    let cpus = match matches.value_of("cpus") {
+    let mut cpus = match matches.value_of("cpus") {
         Some(c) => match c.parse::<u32>() {
             Err(_) => {
                 println!("Invalid value for \"cpus\"");
@@ -114,6 +119,47 @@ pub fn create(cfg: &mut KrunvmConfig, matches: &ArgMatches) {
     }
 
     let mut args = get_buildah_args(cfg, BuildahCommand::From);
+
+    #[cfg(target_os = "macos")]
+    let force_x86 = matches.is_present("x86");
+
+    #[cfg(target_os = "macos")]
+    if force_x86 {
+        let home = match std::env::var("HOME") {
+            Err(e) => {
+                println!("Error reading \"HOME\" enviroment variable: {}", e);
+                std::process::exit(-1);
+            }
+            Ok(home) => home,
+        };
+
+        let path = format!("{}/{}", home, KRUNVM_ROSETTA_FILE);
+        if !Path::new(&path).is_file() {
+            println!(
+                "
+To use Rosetta for Linux you need to create the file...
+
+{}
+
+...with the contents that the \"rosetta\" binary expects to be served from
+its specific ioctl.
+
+For more information, please refer to this post:
+https://threedots.ovh/blog/2022/06/quick-look-at-rosetta-on-linux/
+",
+                path
+            );
+            std::process::exit(-1);
+        }
+
+        if cpus != 1 {
+            println!("x86 microVMs on Aarch64 are restricted to 1 CPU");
+            cpus = 1;
+        }
+        args.push("--arch".to_string());
+        args.push("x86_64".to_string());
+    }
+
     args.push(image.to_string());
 
     let output = match Command::new("buildah")
@@ -161,6 +207,10 @@ pub fn create(cfg: &mut KrunvmConfig, matches: &ArgMatches) {
     let rootfs = mount_container(cfg, &vmcfg).unwrap();
     export_container_config(cfg, &rootfs, image).unwrap();
     fix_resolv_conf(&rootfs, dns).unwrap();
+    #[cfg(target_os = "macos")]
+    if force_x86 {
+        _ = fs::create_dir(format!("{}/.rosetta", rootfs));
+    }
     umount_container(cfg, &vmcfg).unwrap();
 
     cfg.vmconfig_map.insert(name.clone(), vmcfg);

src/create.rs

@@ -246,65 +246,6 @@ fn main() {
                         .takes_value(true),
                 ),
         )
-        .subcommand(
-            App::new("create")
-                .about("Create a new microVM")
-                .arg(
-                    Arg::with_name("cpus")
-                        .long("cpus")
-                        .help("Number of vCPUs")
-                        .takes_value(true),
-                )
-                .arg(
-                    Arg::with_name("mem")
-                        .long("mem")
-                        .help("Amount of RAM in MiB")
-                        .takes_value(true),
-                )
-                .arg(
-                    Arg::with_name("dns")
-                        .long("dns")
-                        .help("DNS server to use in the microVM")
-                        .takes_value(true),
-                )
-                .arg(
-                    Arg::with_name("workdir")
-                        .long("workdir")
-                        .short("w")
-                        .help("Working directory inside the microVM")
-                        .takes_value(true)
-                        .default_value(""),
-                )
-                .arg(
-                    Arg::with_name("volume")
-                        .long("volume")
-                        .short("v")
-                        .help("Volume in form \"host_path:guest_path\" to be exposed to the guest")
-                        .takes_value(true)
-                        .multiple(true)
-                        .number_of_values(1),
-                )
-                .arg(
-                    Arg::with_name("port")
-                        .long("port")
-                        .short("p")
-                        .help("Port in format \"host_port:guest_port\" to be exposed to the host")
-                        .takes_value(true)
-                        .multiple(true)
-                        .number_of_values(1),
-                )
-                .arg(
-                    Arg::with_name("name")
-                        .long("name")
-                        .help("Assign a name to the VM")
-                        .takes_value(true),
-                )
-                .arg(
-                    Arg::with_name("IMAGE")
-                        .help("OCI image to use as template")
-                        .required(true),
-                ),
-        )
         .subcommand(
             App::new("delete").about("Delete an existing microVM").arg(
                 Arg::with_name("NAME")
@@ -348,6 +289,75 @@ fn main() {
                 ),
         );
 
+    let mut create = App::new("create")
+        .about("Create a new microVM")
+        .arg(
+            Arg::with_name("cpus")
+                .long("cpus")
+                .help("Number of vCPUs")
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name("mem")
+                .long("mem")
+                .help("Amount of RAM in MiB")
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name("dns")
+                .long("dns")
+                .help("DNS server to use in the microVM")
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name("workdir")
+                .long("workdir")
+                .short("w")
+                .help("Working directory inside the microVM")
+                .takes_value(true)
+                .default_value(""),
+        )
+        .arg(
+            Arg::with_name("volume")
+                .long("volume")
+                .short("v")
+                .help("Volume in form \"host_path:guest_path\" to be exposed to the guest")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+        )
+        .arg(
+            Arg::with_name("port")
+                .long("port")
+                .short("p")
+                .help("Port in format \"host_port:guest_port\" to be exposed to the host")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+        )
+        .arg(
+            Arg::with_name("name")
+                .long("name")
+                .help("Assign a name to the VM")
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name("IMAGE")
+                .help("OCI image to use as template")
+                .required(true),
+        );
+
+    if cfg!(target_os = "macos") {
+        create = create.arg(
+            Arg::with_name("x86")
+                .long("x86")
+                .short("x")
+                .help("Create a x86_64 microVM even on an Aarch64 host"),
+        );
+    }
+
+    app = app.subcommand(create);
+
     let matches = app.clone().get_matches();
 
     #[cfg(target_os = "macos")]