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hypha: implement write overlay on top of image

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This commit is contained in:
Alex Zenla
2024-01-22 03:00:58 -08:00
parent 1980e870ba
commit f3103c6c51
1 changed files with 56 additions and 8 deletions
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64
hypha/src/container/init.rs
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@ -9,6 +9,13 @@ const CONFIG_BLOCK_DEVICE_PATH: &str = "/dev/xvdb";
const IMAGE_MOUNT_PATH: &str = "/image";
const CONFIG_MOUNT_PATH: &str = "/config";
const OVERLAY_MOUNT_PATH: &str = "/overlay";
const OVERLAY_IMAGE_BIND_PATH: &str = "/overlay/image";
const OVERLAY_WORK_PATH: &str = "/overlay/work";
const OVERLAY_UPPER_PATH: &str = "/overlay/upper";
const PIVOT_PATH: &str = "/pivot";
const IMAGE_CONFIG_JSON_PATH: &str = "/config/image/config.json";
@ -26,8 +33,10 @@ impl ContainerInit {
}
pub fn init(&mut self) -> Result<()> {
self.prepare_mounts()?;
self.mount_early()?;
let config = self.parse_image_config()?;
self.mount_late()?;
if let Some(cfg) = config.config() {
if let Some(cmd) = cfg.cmd() {
println!("image command: {:?}", cmd);
@ -36,7 +45,7 @@ impl ContainerInit {
Ok(())
}
fn prepare_mounts(&mut self) -> Result<()> {
fn mount_early(&mut self) -> Result<()> {
let image_mount_path = Path::new(IMAGE_MOUNT_PATH);
let config_mount_path = Path::new(CONFIG_MOUNT_PATH);
self.mount_squashfs(Path::new(IMAGE_BLOCK_DEVICE_PATH), image_mount_path)?;
@ -44,12 +53,6 @@ impl ContainerInit {
Ok(())
}
fn parse_image_config(&mut self) -> Result<ImageConfiguration> {
let image_config_path = Path::new(IMAGE_CONFIG_JSON_PATH);
let config = ImageConfiguration::from_file(image_config_path)?;
Ok(config)
}
fn mount_squashfs(&mut self, from: &Path, to: &Path) -> Result<()> {
if !to.is_dir() {
fs::create_dir(to)?;
@ -60,4 +63,49 @@ impl ContainerInit {
.mount(from, to)?;
Ok(())
}
fn mount_late(&mut self) -> Result<()> {
self.mount_overlay_tmpfs()?;
self.bind_image_to_overlay_tmpfs()?;
self.mount_overlay_to_pivot()?;
Ok(())
}
fn mount_overlay_tmpfs(&mut self) -> Result<()> {
fs::create_dir(OVERLAY_MOUNT_PATH)?;
Mount::builder()
.fstype(FilesystemType::Manual("tmpfs"))
.mount("tmpfs", OVERLAY_MOUNT_PATH)?;
fs::create_dir(OVERLAY_UPPER_PATH)?;
fs::create_dir(OVERLAY_WORK_PATH)?;
Ok(())
}
fn bind_image_to_overlay_tmpfs(&mut self) -> Result<()> {
fs::create_dir(OVERLAY_IMAGE_BIND_PATH)?;
Mount::builder()
.fstype(FilesystemType::Manual("none"))
.flags(MountFlags::BIND | MountFlags::RDONLY)
.mount(IMAGE_MOUNT_PATH, OVERLAY_IMAGE_BIND_PATH)?;
Ok(())
}
fn mount_overlay_to_pivot(&mut self) -> Result<()> {
fs::create_dir(PIVOT_PATH)?;
Mount::builder()
.fstype(FilesystemType::Manual("overlay"))
.flags(MountFlags::NOATIME)
.data(&format!(
"lowerdir={},upperdir={},workdir={}",
OVERLAY_IMAGE_BIND_PATH, OVERLAY_UPPER_PATH, OVERLAY_WORK_PATH
))
.mount(format!("overlayfs:{}", OVERLAY_MOUNT_PATH), PIVOT_PATH)?;
Ok(())
}
fn parse_image_config(&mut self) -> Result<ImageConfiguration> {
let image_config_path = Path::new(IMAGE_CONFIG_JSON_PATH);
let config = ImageConfiguration::from_file(image_config_path)?;
Ok(config)
}
}