banger/docs/advanced.md
Thales Maciel 2a7f55f028
vm run: ship tracked files only by default; add --include-untracked + --dry-run
Workspace-mode vm run and vm workspace prepare used to copy both
tracked AND untracked non-ignored files into the guest. That silently
catches local .env files, scratch notes, credentials, and any other
working-tree state a developer hasn't explicitly gitignored — a real
data-exposure footgun given the golden image ships Docker and the
usual dev tooling.

Flip the default to tracked-only. Users who actually want the fuller
set opt in with --include-untracked (documented in both commands'
help). Gitignored files are still always excluded regardless of the
flag.

Add --dry-run to both vm run and vm workspace prepare. Dry-run
inspects the repo CLI-side (no VM created, no daemon RPC needed since
the daemon is always local and the inspection is a pure git read),
prints the exact file list + mode, and exits. A byte-level preview of
what would land in the guest.

When running real (non-dry) and untracked files exist in the repo but
are being skipped under the new default, print a one-line notice
pointing to --include-untracked so users aren't surprised when the
guest is missing something they expected.

Signature changes:
- ListOverlayPaths takes an includeUntracked bool (tracked always;
  untracked gated by flag).
- InspectRepo takes the same flag and passes it through.
- VMWorkspacePrepareParams gains IncludeUntracked.
- WorkspaceService.workspaceInspectRepo seam signature widened to
  match (4 callers in tests updated).

New workspace package tests cover both modes and verify that
gitignored files never leak regardless of the flag.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 19:53:17 -03:00

3.1 KiB

Advanced flows

banger vm run covers the common sandbox case. This doc is for the rest: scripting, arbitrary images, custom rootfs stacks, long-lived guest processes.

vm create — the low-level primitive

Use when you want to provision without starting, or when you need to script VM creation piecewise.

banger vm create --image debian-bookworm --name testbox --no-start
banger vm start testbox
banger vm ssh testbox
banger vm stop testbox
banger vm delete testbox

Sweep every non-running VM (stopped, created, error) with:

banger vm prune          # interactive confirmation
banger vm prune -f       # skip the prompt

vm create is synchronous by default, but on a TTY it shows live progress until the VM is fully ready.

image pull <oci-ref> — arbitrary container images

For images outside banger's catalog, pull from any OCI registry:

banger image pull docker.io/library/alpine:3.20 --kernel-ref generic-6.12

Layers are flattened, ownership is fixed (setuid binaries, root-owned config preserved), banger's guest agents are injected, and a first-boot systemd service installs openssh-server via the guest's package manager so the VM is reachable on first boot.

See docs/oci-import.md for supported distros, caveats, and the internal/imagepull design.

image register — existing host-side stack

If you already have an ext4 rootfs, a kernel, optional initrd, and optional modules as files on disk:

banger image register --name base \
  --rootfs /abs/path/rootfs.ext4 \
  --kernel-ref generic-6.12

You can mix --kernel-ref (a cataloged kernel) with --rootfs from disk, or pass --kernel /abs/path/vmlinux for a one-off kernel.

For reproducible custom images, write a Dockerfile and publish it to an image catalog. See docs/image-catalog.md.

Workspace primitive

vm run ./repo (see README) handles the common case. For a manual flow against an already-running VM, vm workspace prepare materialises a local git checkout into the guest:

banger vm workspace prepare <vm> ./other-repo --guest-path /root/repo

Default guest path is /root/repo; default mode is a shallow metadata copy plus a tracked-files overlay. Untracked files are skipped by default — pass --include-untracked to ship untracked non-ignored files too (the old behaviour). Pass --dry-run to list the exact file set without touching the guest. For repositories with submodules, pass --mode full_copy.

Inspecting boot failures

When a VM's create flow errors ("ssh did not come up within 90s" or similar), the VM is kept alive for inspection:

  • banger vm logs <name> — the firecracker serial console output, the best window into a stuck boot (systemd unit failures, kernel panics, missing modules).
  • banger vm ports <name> — what's listening in the guest. Works as long as banger's vsock agent has come up, even if SSH is wedged.
  • banger vm show <name> — daemon-side state (IP, PID, overlay paths).

--rm on vm run intentionally does NOT fire when the initial ssh wait times out, so the VM stays around for post-mortem.