bolt-lite

Minimal, read-only BoltDB parser focused on containerd metadata.db. It keeps everything in-memory, walks buckets, and exposes a tiny API that mirrors common containerd layouts.

Features

• Parse BoltDB meta pages and B+tree without unsafe code.
• Bucket navigation (Tx::bucket, Tx::bucket_path), entry lookup, and iteration.
• Cursor over leaf entries and simple stats.
• No writes or page mutations.

Quick start

use bolt_lite::Bolt;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let db = Bolt::open_ro("/var/lib/containerd/io.containerd.metadata.v1.bolt/meta.db")?;
    let tx = db.begin()?;
    let images = tx
        .bucket_path(&[b"v1", b"default", b"images"])
        .expect("images bucket")
        .iter_buckets();

    for (name, bucket) in images {
        if let Some(desc) = bucket.get(b"target") {
            println!("{} -> {} bytes", String::from_utf8_lossy(&name), desc.len());
        }
    }
    Ok(())
}

Buckets and helpers

• Tx::bucket_path handles nested buckets by byte segments.
• Bucket::get and Bucket::bucket fetch values or nested buckets.
• Bucket::cursor iterates leaf entries; Bucket::iter_buckets discovers child buckets with BUCKET_VALUE_FLAG set.
• ok_opt converts Result<T, E> into Option<T> when you want fallbacks.

Notes

• Only supports read-only access; checksum and freelist validation are intentionally skipped to tolerate containerd variants.
• Page sizes outside 1 KiB–64 KiB are rejected.
• Inline buckets (root=0) are handled by inlining the value bytes.

License

MIT