# repo-sync

A universal Linux package repository synchronization tool. It mirrors remote
repositories into a local directory tree, preserving the upstream layout so
the result can be served directly to package managers.

Supported repository types:

- **rpm** — yum/dnf repositories (`repodata/repomd.xml`), including
  plain-text mirrorlist and metalink URLs with failover between mirrors.
- **deb** — apt repositories, both standard (`dists/<suite>` with a shared
  `pool/`) and flat layouts, including `Acquire-By-Hash` population.
- **arch** — pacman repositories (`<name>.db`), including detached package
  signatures and companion metadata (`.files`, `.db.tar.gz`, `.links.tar.gz`).
- **apk** — Alpine Linux repositories (`APKINDEX.tar.gz` with packages
  beside it).

## Usage

```
repo-sync <type> [flags] <url> [<url> ...] <destination-directory>
```

The last argument is always the destination directory; every argument before
it is a repository or mirrorlist URL, synchronized one after the other.

```sh
# Mirror one repository. The URL path is copied below the destination, so
# this produces ./mirror/repos/CentOS/7/EA4/.
repo-sync rpm https://example.com/repos/CentOS/7/EA4/ ./mirror

# Trim the first two path components: ./mirror/7/EA4/.
repo-sync rpm --trim 2 https://example.com/repos/CentOS/7/EA4/ ./mirror

# No path copying at all: the repository lands directly in ./mirror.
repo-sync rpm --flat https://example.com/repos/CentOS/7/EA4/ ./mirror

# Multiple repositories in one run.
repo-sync rpm https://example.com/repos/a/ https://example.com/repos/b/ ./mirror

# Crawl directory listings for repositories, at most 4 levels deep.
repo-sync rpm --discover --depth 4 https://example.com/repos/ ./mirror

# A pacman repository. The database name is discovered from the directory
# listing, or by probing URL path segments when listings are disabled.
repo-sync arch https://example.com/archlinux/core/os/x86_64/ ./mirror

# An Alpine repository is one arch directory; discovery syncs every arch
# of a release/repo tree in one run.
repo-sync apk https://dl-cdn.alpinelinux.org/alpine/v3.24/community/x86_64/ ./mirror
repo-sync apk --discover --depth 1 https://dl-cdn.alpinelinux.org/alpine/v3.24/community/ ./mirror

# A Fedora-style metalink URL; mirrors are used in preference order. The
# mirrors' paths differ, so --flat keeps the destination stable.
repo-sync rpm --flat 'https://mirrors.fedoraproject.org/metalink?repo=epel-9&arch=x86_64' ./mirror/epel9

# An apt suite. Pool files resolve against the archive root, producing
# ./mirror/debian/dists/bookworm/ and ./mirror/debian/pool/.
repo-sync deb https://deb.example.com/debian/dists/bookworm ./mirror

# Limit an apt mirror to specific components and architectures. Include
# "source" as an architecture to keep source indexes.
repo-sync deb --component main --arch amd64,source https://deb.example.com/debian/dists/bookworm ./mirror
```

## Building

```sh
make
```

The build stamps the binary with the contents of the `VERSION` file plus the
git commit and build date, shown by `repo-sync --version`. A plain
`go build` also works but reports the version as `dev`.

## Testing

```sh
make test
```

The suite is hermetic: fixture repositories for every supported format
(rpm, deb, arch, apk) are generated in temp directories and served over
local HTTP, so no network access is required.