Skrog

Air-gapped install

On this page

Isolated-network machines cannot use Docker Desktop at all — it phones home to log in and check for updates. Skrog installs from a single file, with zero network calls, and this page states that guarantee and how to check it.

Two steps

On a connected machine, pack the engine into a bundle:

skrog bundle -o skrog-bundle.zip

This downloads the rootfs, verifies its SHA-256, and writes a .zip containing the rootfs and a skrog.lock (engine version, rootfs checksum, component versions). Copy the file to the isolated machine by whatever means you already trust (USB, internal share).

On the isolated machine, install from it:

skrog install --offline skrog-bundle.zip
skrog start
docker run --rm hello-world

The guarantee

skrog install --offline reads the rootfs from the bundle and imports it. It does not resolve the release manifest, contact GitHub, or open any socket:

  • The rootfs source is a local file extracted from the bundle. The only importer in the codebase is the same checksum-verified path a networked install uses, so the bundle’s rootfs is verified against the lock’s SHA-256 before import — a corrupt or swapped bundle is refused, not installed.
  • Nothing is fetched as “latest,” on this step or any other. Version pinning is a contract, and the bundle is the pin.

Any network access during install --offline is a bug — please report it.

How to audit it

The promise is checkable, which is the point:

  • Run it disconnected. Pull the network on the target machine (or block the skrog.exe process at the firewall) and run skrog install --offline. It completes; nothing times out waiting on a download.
  • Watch the process. Run it under a network monitor (Process Monitor, Resource Monitor, or a packet capture). There are no connections.
  • Read the bundle. A .zip is inspectable with any tool: skrog.lock is plain JSON, and the rootfs entry’s SHA-256 is what the install verifies.

Reproducibility

The bundle embeds a skrog.lock, so an air-gapped install is also a reproducible one — every isolated machine installs the identical, verified engine. See declarative-install.md for skrog.lock and the fleet story.

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