containerd-store

A small, read-only helper crate to explore containerd metadata and content. It resolves images from containerd's meta.db, finds their content digests, and can export or iterate images without needing a running daemon.

Features

• Open containerd metadata (io.containerd.metadata.v1.bolt/meta.db) and read images by namespace.
• Resolve image descriptors and locate blobs under io.containerd.content.v1.content/blobs.
• Export images (and meta.db) into a portable bundle; supports multiple images and deduplicates blobs.
• Optional bucket-path logging (bucket-logging feature) to trace layout differences across vendors.

Quick start: list and resolve

use containerd_store::{ContainerdStore, ImageEntry};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = ContainerdStore::open(
        "~/.local/share/containerd",
        "default",
    )?;

    let images: Vec<ImageEntry> = store.list_images()?;
    for img in &images {
        println!("{} -> {} ({} bytes)", img.name, img.target.digest, img.target.size);
    }

    let resolved = store.resolve_image("busybox:latest")?;
    println!("manifest at {}", resolved.manifest_path.display());
    Ok(())
}

Export helper

• Single image: export_image_to_dir(&store, "busybox:latest", "./out")
• Multiple images: export_images_to_dir(&store, &["foo:tag", "bar:tag"], "./out")

Exports include:

• io.containerd.metadata.v1.bolt/meta.db (so bundles are self-contained)
• All referenced manifests, configs, and layers under io.containerd.content.v1.content/blobs/
• Deduplicated blobs across all exported images

Bucket-path logging

Enable bucket-logging feature and register a logger:

containerd_store::set_bucket_match_logger(|m| {
    eprintln!("matched {:?}: {}", m.kind, m.path.join("/"));
}).ok();

This is useful when debugging vendor-specific layout changes.

Notes

• Read-only: no mutations to containerd data.
• Size parsing tolerates missing size fields (defaults to 0, warns once).
• Platform selection prefers linux/amd64 when walking OCI indexes; falls back to the first entry.

License

MIT