feat: oci packer can now use mksquashfs if available (#70)

* feat: oci packer can now use mksquashfs if available

* fix: use nproc in kernel build script for default jobs, and fix DEV.md guide

* feat: working erofs backend

crates/runtime/src/launch.rs

@@ -8,7 +8,9 @@ use anyhow::{anyhow, Result};
 use ipnetwork::{IpNetwork, Ipv4Network};
 use krata::launchcfg::{
     LaunchInfo, LaunchNetwork, LaunchNetworkIpv4, LaunchNetworkIpv6, LaunchNetworkResolver,
+    LaunchPackedFormat, LaunchRoot,
 };
+use krataoci::packer::OciPackerFormat;
 use krataoci::progress::OciProgressContext;
 use tokio::sync::Semaphore;
 use uuid::Uuid;
@@ -19,13 +21,14 @@ use crate::cfgblk::ConfigBlock;
 use crate::RuntimeContext;
 use krataoci::{
     cache::ImageCache,
-    compiler::{ImageCompiler, ImageInfo},
+    compiler::{ImageInfo, OciImageCompiler},
     name::ImageName,
 };
 
 use super::{GuestInfo, GuestState};
 
 pub struct GuestLaunchRequest<'a> {
+    pub format: LaunchPackedFormat,
     pub uuid: Option<Uuid>,
     pub name: Option<&'a str>,
     pub image: &'a str,
@@ -58,6 +61,10 @@ impl GuestLauncher {
                 request.image,
                 &context.image_cache,
                 &context.oci_progress_context,
+                match request.format {
+                    LaunchPackedFormat::Squashfs => OciPackerFormat::Squashfs,
+                    LaunchPackedFormat::Erofs => OciPackerFormat::Erofs,
+                },
             )
             .await?;
 
@@ -77,6 +84,9 @@ impl GuestLauncher {
         let ipv6_network_mask: u32 = 10;
 
         let launch_config = LaunchInfo {
+            root: LaunchRoot {
+                format: request.format.clone(),
+            },
             hostname: Some(
                 request
                     .name
@@ -110,9 +120,9 @@ impl GuestLauncher {
         cfgblk.build(&launch_config)?;
 
         let image_squashfs_path = image_info
-            .image_squashfs
+            .image
             .to_str()
-            .ok_or_else(|| anyhow!("failed to convert image squashfs path to string"))?;
+            .ok_or_else(|| anyhow!("failed to convert image path to string"))?;
 
         let cfgblk_dir_path = cfgblk
             .dir
@@ -257,10 +267,11 @@ impl GuestLauncher {
         image: &str,
         image_cache: &ImageCache,
         progress: &OciProgressContext,
+        format: OciPackerFormat,
     ) -> Result<ImageInfo> {
         let image = ImageName::parse(image)?;
-        let compiler = ImageCompiler::new(image_cache, None, progress.clone())?;
-        compiler.compile(id, &image).await
+        let compiler = OciImageCompiler::new(image_cache, None, progress.clone())?;
+        compiler.compile(id, &image, format).await
     }
 
     async fn allocate_ipv4(&self, context: &RuntimeContext) -> Result<Ipv4Addr> {