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/guest/src/init.rs

@@ -4,7 +4,7 @@ use futures::stream::TryStreamExt;
 use ipnetwork::IpNetwork;
 use krata::ethtool::EthtoolHandle;
 use krata::idm::client::IdmClient;
-use krata::launchcfg::{LaunchInfo, LaunchNetwork};
+use krata::launchcfg::{LaunchInfo, LaunchNetwork, LaunchPackedFormat};
 use libc::{sethostname, setsid, TIOCSCTTY};
 use log::{trace, warn};
 use nix::ioctl_write_int_bad;
@@ -80,11 +80,13 @@ impl GuestInit {
         let idm = IdmClient::open("/dev/hvc1")
             .await
             .map_err(|x| anyhow!("failed to open idm client: {}", x))?;
-        self.mount_squashfs_images().await?;
+        self.mount_config_image().await?;
 
         let config = self.parse_image_config().await?;
         let launch = self.parse_launch_config().await?;
 
+        self.mount_root_image(launch.root.format.clone()).await?;
+
         self.mount_new_root().await?;
         self.bind_new_root().await?;
 
@@ -98,11 +100,19 @@ impl GuestInit {
             if result != 0 {
                 warn!("failed to set hostname: {}", result);
             }
+
+            let etc = PathBuf::from_str("/etc")?;
+            if !etc.exists() {
+                fs::create_dir(&etc).await?;
+            }
+            let mut etc_hostname = etc;
+            etc_hostname.push("hostname");
+            fs::write(&etc_hostname, hostname + "\n").await?;
         }
 
         if let Some(network) = &launch.network {
             trace!("initializing network");
-            if let Err(error) = self.network_setup(network).await {
+            if let Err(error) = self.network_setup(&launch, network).await {
                 warn!("failed to initialize network: {}", error);
             }
         }
@@ -177,24 +187,41 @@ impl GuestInit {
         Ok(())
     }
 
-    async fn mount_squashfs_images(&mut self) -> Result<()> {
-        trace!("mounting squashfs images");
-        let image_mount_path = Path::new(IMAGE_MOUNT_PATH);
+    async fn mount_config_image(&mut self) -> Result<()> {
+        trace!("mounting config image");
         let config_mount_path = Path::new(CONFIG_MOUNT_PATH);
-        self.mount_squashfs(Path::new(IMAGE_BLOCK_DEVICE_PATH), image_mount_path)
-            .await?;
-        self.mount_squashfs(Path::new(CONFIG_BLOCK_DEVICE_PATH), config_mount_path)
+        self.mount_image(
+            Path::new(CONFIG_BLOCK_DEVICE_PATH),
+            config_mount_path,
+            LaunchPackedFormat::Squashfs,
+        )
+        .await?;
+        Ok(())
+    }
+
+    async fn mount_root_image(&mut self, format: LaunchPackedFormat) -> Result<()> {
+        trace!("mounting root image");
+        let image_mount_path = Path::new(IMAGE_MOUNT_PATH);
+        self.mount_image(Path::new(IMAGE_BLOCK_DEVICE_PATH), image_mount_path, format)
             .await?;
         Ok(())
     }
 
-    async fn mount_squashfs(&mut self, from: &Path, to: &Path) -> Result<()> {
-        trace!("mounting squashfs image {:?} to {:?}", from, to);
+    async fn mount_image(
+        &mut self,
+        from: &Path,
+        to: &Path,
+        format: LaunchPackedFormat,
+    ) -> Result<()> {
+        trace!("mounting {:?} image {:?} to {:?}", format, from, to);
         if !to.is_dir() {
             fs::create_dir(to).await?;
         }
         Mount::builder()
-            .fstype(FilesystemType::Manual("squashfs"))
+            .fstype(FilesystemType::Manual(match format {
+                LaunchPackedFormat::Squashfs => "squashfs",
+                LaunchPackedFormat::Erofs => "erofs",
+            }))
             .flags(MountFlags::RDONLY)
             .mount(from, to)?;
         Ok(())
@@ -287,7 +314,7 @@ impl GuestInit {
         Ok(())
     }
 
-    async fn network_setup(&mut self, network: &LaunchNetwork) -> Result<()> {
+    async fn network_setup(&mut self, cfg: &LaunchInfo, network: &LaunchNetwork) -> Result<()> {
         trace!("setting up network for link");
 
         let etc = PathBuf::from_str("/etc")?;
@@ -295,14 +322,33 @@ impl GuestInit {
             fs::create_dir(etc).await?;
         }
         let resolv = PathBuf::from_str("/etc/resolv.conf")?;
-        let mut lines = vec!["# krata resolver configuration".to_string()];
-        for nameserver in &network.resolver.nameservers {
-            lines.push(format!("nameserver {}", nameserver));
+
+        {
+            let mut lines = vec!["# krata resolver configuration".to_string()];
+            for nameserver in &network.resolver.nameservers {
+                lines.push(format!("nameserver {}", nameserver));
+            }
+
+            let mut conf = lines.join("\n");
+            conf.push('\n');
+            fs::write(resolv, conf).await?;
+        }
+
+        let hosts = PathBuf::from_str("/etc/hosts")?;
+        if let Some(ref hostname) = cfg.hostname {
+            let mut lines = if hosts.exists() {
+                fs::read_to_string(&hosts)
+                    .await?
+                    .lines()
+                    .map(|x| x.to_string())
+                    .collect::<Vec<_>>()
+            } else {
+                vec!["127.0.0.1 localhost".to_string()]
+            };
+            lines.push(format!("127.0.1.1 {}", hostname));
+            fs::write(&hosts, lines.join("\n") + "\n").await?;
         }
 
-        let mut conf = lines.join("\n");
-        conf.push('\n');
-        fs::write(resolv, conf).await?;
         self.network_configure_ethtool(network).await?;
         self.network_configure_link(network).await?;
         Ok(())