Separates what a VM IS (durable intent + identity + deterministic
derived paths — `VMRuntime`) from what is CURRENTLY TRUE about it
(firecracker PID, tap device, loop devices, dm-snapshot target — new
`VMHandles`). The durable state lives in the SQLite `vms` row; the
transient state lives in an in-memory cache on the daemon plus a
per-VM `handles.json` scratch file inside VMDir, rebuilt at startup
from OS inspection. Nothing kernel-level rides the SQLite schema
anymore.
Why:
Persisting ephemeral process handles to SQLite forced reconcile to
treat "running with a stale PID" as a first-class case and mix it
with real state transitions. The schema described what we last
observed, not what the VM is. Every time the observation model
shifted (tap pool, DM naming, pgrep fallback) the reconcile logic
grew a new branch. Splitting lets each layer own what it's good at:
durable records describe intent, in-memory cache + scratch file
describe momentary reality.
Shape:
- `model.VMHandles` = PID, TapDevice, BaseLoop, COWLoop, DMName,
DMDev. Never in SQLite.
- `VMRuntime` keeps: State, GuestIP, APISockPath, VSockPath,
VSockCID, LogPath, MetricsPath, DNSName, VMDir, SystemOverlay,
WorkDiskPath, LastError. All durable or deterministic.
- `handleCache` on `*Daemon` — mutex-guarded map + scratch-file
plumbing (`writeHandlesFile` / `readHandlesFile` /
`rediscoverHandles`). See `internal/daemon/vm_handles.go`.
- `d.vmAlive(vm)` replaces the 20+ inline
`vm.State==Running && ProcessRunning(vm.Runtime.PID, apiSock)`
spreads. Single source of truth for liveness.
- Startup reconcile: per running VM, load the scratch file, pgrep
the api sock, either keep (cache seeded from scratch) or demote
to stopped (scratch handles passed to cleanupRuntime first so DM
/ loops / tap actually get torn down).
Verification:
- `go test ./...` green.
- Live: `banger vm run --name handles-test -- cat /etc/hostname`
starts; `handles.json` appears in VMDir with the expected PID,
tap, loops, DM.
- `kill -9 $(pgrep bangerd)` while the VM is running, re-invoke the
CLI, daemon auto-starts, reconcile recognises the VM as alive,
`banger vm ssh` still connects, `banger vm delete` cleans up.
Tests added:
- vm_handles_test.go: scratch-file roundtrip, missing/corrupt file
behaviour, cache concurrency, rediscoverHandles prefers pgrep
over scratch, returns scratch contents even when process is
dead (so cleanup can tear down kernel state).
- vm_test.go: reconcile test rewritten to exercise the new flow
(write scratch → reconcile reads it → verifies process is gone →
issues dmsetup/losetup teardown).
ARCHITECTURE.md updated; `handles` added to Daemon field docs.
Moves the stateless parts of the guest-session subsystem into
internal/daemon/session:
- consts (BackendSSH, attach/transport kinds, StateRoot, LogTailLineDefault)
- StateSnapshot plus ParseState / InspectStateFromDir / ApplyStateSnapshot / StateChanged
- 10 on-guest path helpers (StateDir, StdoutLogPath, StdinPipePath, …)
- 3 bash script generators (Script, InspectScript, SignalScript)
- small utilities (ShellQuote, ExitCode, CloneStringMap, TailFileContent,
ProcessAlive + syscallKill test seam, FormatStepError)
- launch helpers (DefaultName, DefaultCWD, FailLaunch,
NormalizeRequiredCommands, CWDPreflightScript, CommandPreflightScript,
AttachInputCommand, AttachTailCommand, EnvLines)
Callers inside the daemon package import the new package under the
alias "sess" to avoid colliding with the local `session model.GuestSession`
variables threaded through the orchestrator code. guest_sessions.go
shrinks from 616 → 156 LOC; session_stream.go, session_attach.go,
session_lifecycle.go, workspace.go, and guest_sessions_test.go rewire to
the exported names.
The orchestrator methods (StartGuestSession, BeginGuestSessionAttach,
SendToGuestSession, GuestSessionLogs, refresh/inspect, sessionRegistry,
guestSessionController) stay on *Daemon. Full Manager-style extraction
would need prerequisite phases (operation protocol, workdisk helpers),
mirroring Phase 4a's trade-off.
All tests green.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
guest.session.send — write to a pipe-mode session's stdin without
holding the exclusive attach. The daemon dials a fresh SSH connection,
uploads the payload to a temp file, and cats it into the session's
named FIFO. Linux atomicity for writes ≤ PIPE_BUF covers all pi RPC
JSONL lines. Attach exclusivity is unchanged.
vm.workspace.export — pull changes from guest back to host. Runs
`git add -A && git diff --cached HEAD --binary` inside the guest via a
new RunScriptOutput helper on guest.Client (stdout-only capture,
distinct from RunScript which merges stderr). Returns a binary-safe
patch and a list of changed files. CLI writes the patch to stdout for
`| git apply` or to a file via --output.
RunScriptOutput is implemented as a direct SSH session (same pattern as
runSession) rather than going through StartCommand/StreamSession to
avoid closing the underlying Client, which is required since
ExportVMWorkspace calls it twice on the same connection.
New files: internal/daemon/workspace_test.go
Guest session cwd and command preflight helpers were emitting literal
`\\n` separators, so the guest shell saw malformed one-line scripts and
could fail `preflight_cwd` even when `/root/repo` already existed.
Replace those builders with real newlines, and fix the nearby attach
helper commands that were making the same mistake.
Add a small daemon guest-SSH seam so workspace preparation and session
start can share a fake backend in tests, then cover the regression with
an end-to-end daemon test for `PrepareVMWorkspace` followed by
`StartGuestSession` on `/root/repo`.
Validation: `GOCACHE=/tmp/banger-gocache go test ./internal/daemon` and
`GOCACHE=/tmp/banger-gocache go test ./...`.
