hypha: use manifest digest as part of key in image cache

hypha/src/image/fetch.rs

@@ -47,7 +47,11 @@ impl RegistryClient {
         Ok(copy(reader.deref_mut(), dest)?)
     }
 
-    pub fn get_manifest(&mut self, name: &str, reference: &str) -> Result<ImageManifest> {
+    pub fn get_manifest_with_digest(
+        &mut self,
+        name: &str,
+        reference: &str,
+    ) -> Result<(ImageManifest, String)> {
         let url = self
             .url
             .join(&format!("/v2/{}/manifests/{}", name, reference))?;
@@ -69,10 +73,14 @@ impl RegistryClient {
             let descriptor = self
                 .pick_manifest(index)
                 .ok_or_else(|| HyphaError::new("unable to pick manifest from index"))?;
-            return self.get_manifest(name, descriptor.digest());
+            return self.get_manifest_with_digest(name, descriptor.digest());
         }
+        let digest = response
+            .header("Docker-Content-Digest")
+            .ok_or_else(|| HyphaError::new("fetching manifest did not yield a content digest"))?
+            .to_string();
         let manifest = ImageManifest::from_reader(response.into_reader())?;
-        Ok(manifest)
+        Ok((manifest, digest))
     }
 
     fn pick_manifest(&mut self, index: ImageIndex) -> Option<Descriptor> {

hypha/src/image/mod.rs

@@ -6,7 +6,8 @@ use crate::error::{HyphaError, Result};
 use crate::image::cache::ImageCache;
 use crate::image::fetch::RegistryClient;
 use crate::image::name::ImageName;
-use backhand::{FilesystemWriter, NodeHeader};
+use backhand::compression::Compressor;
+use backhand::{FilesystemCompressor, FilesystemWriter, NodeHeader};
 use flate2::read::GzDecoder;
 use log::{debug, trace, warn};
 use oci_spec::image::{Descriptor, ImageConfiguration, ImageManifest, MediaType, ToDockerV2S2};
@@ -125,11 +126,10 @@ impl ImageCompiler<'_> {
             image_dir.to_str().unwrap()
         );
         let mut client = RegistryClient::new(image.registry_url()?)?;
-        let manifest = client.get_manifest(&image.name, &image.reference)?;
-        let manifest_serialized = serde_json::to_string(&manifest)?;
+        let (manifest, digest) = client.get_manifest_with_digest(&image.name, &image.reference)?;
         let cache_key = format!(
-            "manifest\n{}squashfs-version\n{}\n",
-            manifest_serialized, IMAGE_SQUASHFS_VERSION
+            "manifest={}:squashfs-version={}\n",
+            digest, IMAGE_SQUASHFS_VERSION
         );
         let cache_digest = sha256::digest(cache_key);
 
@@ -338,6 +338,7 @@ impl ImageCompiler<'_> {
 
     fn squash(&self, image_dir: &PathBuf, squash_file: &PathBuf) -> Result<()> {
         let mut writer = FilesystemWriter::default();
+        writer.set_compressor(FilesystemCompressor::new(Compressor::Gzip, None)?);
         let walk = WalkDir::new(image_dir).follow_links(false);
         for entry in walk {
             let entry = entry?;

xenclient/src/lib.rs

@@ -195,7 +195,8 @@ impl XenClient {
             let mut count: u32 = 0;
             loop {
                 if count >= 100 {
-                    return Err(XenClientError::new("unable to destroy device"));
+                    warn!("unable to safely destroy backend: {}", backend);
+                    break;
                 }
                 let state = self.store.read_string(&state_path)?;
                 let state = i64::from_str(&state).unwrap_or(-1);