hypha: config as a block device

hypha/src/ctl/cfgblk.rs

@@ -0,0 +1,49 @@
+use crate::error::Result;
+use crate::image::ImageInfo;
+use backhand::{FilesystemWriter, NodeHeader};
+use std::fs;
+use std::fs::File;
+use std::path::PathBuf;
+use uuid::Uuid;
+
+pub struct ConfigBlock<'a> {
+    pub image_info: &'a ImageInfo,
+    pub file: PathBuf,
+}
+
+impl ConfigBlock<'_> {
+    pub fn new<'a>(uuid: &Uuid, image_info: &'a ImageInfo) -> Result<ConfigBlock<'a>> {
+        let mut file = std::env::temp_dir().clone();
+        file.push(format!("hypha-cfg-{}", uuid));
+        fs::create_dir_all(&file)?;
+        file.push("config.squashfs");
+        Ok(ConfigBlock { image_info, file })
+    }
+
+    pub fn build(&self) -> Result<()> {
+        let manifest = self.image_info.config.to_string()?;
+        let mut writer = FilesystemWriter::default();
+        writer.push_dir(
+            "/image",
+            NodeHeader {
+                permissions: 384,
+                uid: 0,
+                gid: 0,
+                mtime: 0,
+            },
+        )?;
+        writer.push_file(
+            manifest.as_bytes(),
+            "/image/config.json",
+            NodeHeader {
+                permissions: 384,
+                uid: 0,
+                gid: 0,
+                mtime: 0,
+            },
+        )?;
+        let mut file = File::create(&self.file)?;
+        writer.write(&mut file)?;
+        Ok(())
+    }
+}

hypha/src/ctl/mod.rs

@@ -1,3 +1,6 @@
+mod cfgblk;
+
+use crate::ctl::cfgblk::ConfigBlock;
 use crate::error::{HyphaError, Result};
 use crate::image::cache::ImageCache;
 use crate::image::name::ImageName;
@@ -55,10 +58,16 @@ impl Controller {
         let uuid = Uuid::new_v4();
         let name = format!("hypha-{uuid}");
         let image_info = self.compile()?;
-        let squashfs_path = image_info
-            .squashfs
+        let cfgblk = ConfigBlock::new(&uuid, &image_info)?;
+        cfgblk.build()?;
+        let cfgblk_squashfs_path = cfgblk
+            .file
             .to_str()
-            .ok_or_else(|| HyphaError::new("failed to convert squashfs path to string"))?;
+            .ok_or_else(|| HyphaError::new("failed to convert config squashfs path to string"))?;
+        let image_squashfs_path = image_info
+            .image_squashfs
+            .to_str()
+            .ok_or_else(|| HyphaError::new("failed to convert image squashfs path to string"))?;
         let config = DomainConfig {
             backend_domid: 0,
             name: &name,
@@ -66,13 +75,21 @@ impl Controller {
             mem_mb: self.mem,
             kernel_path: self.kernel_path.as_str(),
             initrd_path: self.initrd_path.as_str(),
-            cmdline: "elevator=noop",
-            disks: vec![DomainDisk {
-                vdev: "xvda",
-                pdev: squashfs_path,
-                writable: false,
-            }],
+            cmdline: "quiet elevator=noop",
+            disks: vec![
+                DomainDisk {
+                    vdev: "xvda",
+                    pdev: image_squashfs_path,
+                    writable: false,
+                },
+                DomainDisk {
+                    vdev: "xvdb",
+                    pdev: cfgblk_squashfs_path,
+                    writable: false,
+                },
+            ],
         };
-        Ok(self.client.create(&config)?)
+        let domid = self.client.create(&config)?;
+        Ok(domid)
     }
 }