jcoffey-dev
7e04351b0f
Two changes that arrived together: the cutover phase (ARCHITECTURE.md 4.5) is implemented, and the rollback phase is deleted. Recovery from a failed migration is now explicitly the operator's own snapshot or backup, and out of scope for this tool. internal/cutover implements 4.5 as seven checkpointed steps: verify the staged binary's version, install it, preserve and rewrite the service definition, reload, start, wait for a healthy JMAP session, recalculate quotas. The unit is rewritten in place rather than generated from a template. An operator's unit carries hardening options, limits and dependencies this tool has no business having an opinion about, and regenerating it would silently drop them. It repoints ExecStart (preserving systemd's -@:+! prefix characters and every argument after the executable), updates --config, and strips recovery-mode Environment lines - leaving STALWART_RECOVERY_MODE=1 set would recovery-boot the service on every restart, forever. It refuses on a unit with no ExecStart, and on an Environment line mixing a recovery variable with others: a line it only partly understands is one it must not edit. Quota recalculation is the one step allowed to fail without failing the phase. Its wire format is grounded in Stalwart's x:Task schema reference - Task/set creating one AccountMaintenance per account with maintenanceType recalculateQuota - but the upgrade guide only documents the WebUI path, so two details remain inferred and are called out in stalwartapi/task.go: whether the schema's "read-only" annotation on accountId/maintenanceType means "immutable after creation", and whether a finished task simply leaves the queue (TaskStatus documents Pending/Retry/Failed with no success state). Warning rather than failing is the honest response to that uncertainty, and stale counters are an accounting problem next to calling for a restore of a machine that is otherwise migrated and serving mail. Docker deployments are refused outright: cutting a container over means pulling an image and recreating it, not swapping a binary. On removing rollback. The implementation worked and was tested, and it was removed because restoring bytes correctly is not the hard part. It copied file contents and permissions and verified every restored file against a manifest - and did not preserve ownership. Run as root, as this tool requires, it would have produced a byte-perfect, checksum-verified, root-owned data directory that Stalwart, running as its own user, could not open, and it would have reported success. The PostgreSQL path was worse: pg_dump without --clean emits CREATE TABLE + COPY, which fails replaying into a database whose tables still exist, and the ON_ERROR_STOP=1 added so a half-applied restore couldn't be reported as success turned that into a hard failure. None of it had ever run against a real server. A filesystem snapshot has none of these failure modes, because it never lost the metadata to begin with. So cutover's gate is no longer rollback.CanRollBack but an explicit RecoveryPointConfirmed acknowledgement. That is an assertion, not a check - this tool cannot verify someone else's snapshot - and its only value is that nobody migrates a production mail server having never been asked the question. Two consequences are accepted deliberately: restoring any pre-migration recovery point discards mail delivered since, and a failed migration now stops and reports rather than undoing itself. What the tool still does to make a manual restore easier: the old binary is preserved and never deleted, the original service definition is preserved before the rewrite, the settings and principals dumps stay on disk, and every artifact path and checksum stays in the checkpoint where `status <run-id>` can print it. Also removed: the `confirm` command stub and RollbackWindowClosed, whose only purpose was closing a rollback window that no longer exists, and checkpoint.PhaseRollback. Old state.json files still load - JSON ignores the now-unknown field. Still open, and recorded in 8: cutover ignores systemd drop-ins, so an ExecStart or Environment override in stalwart.service.d/*.conf is invisible to the rewrite - including the recovery variable it exists to strip; nothing prevents concurrent runs on the same run-id; and nothing in this repo has ever run against a real Stalwart, real systemd, or a real store.
157 lines
6.6 KiB
Markdown
157 lines
6.6 KiB
Markdown
# stalwart-migrator
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In-place upgrade tool for Stalwart Mail Server, 0.15.5 → latest: no data
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loss, a checkpoint at every step so an interrupted run resumes instead of
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restarting, and automated validation that the server still works afterwards.
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**Recovery from a failed migration is your own snapshot or backup — this
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tool does not undo a migration.** See [Recovery is your
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job](#recovery-is-your-job) before using it on anything you care about.
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Go, standard library only — no external dependencies.
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## Status
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Partially implemented. Roughly 8,800 lines of tested code. Every phase
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except staging now exists as a package, including cutover, but nothing wires
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them into a production run yet, so `run` still refuses.
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| Command | State |
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|---|---|
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| `stalwart-migrate preflight` | **Works** — read-only checks and a migration plan |
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| `stalwart-migrate run --dry-run` | **Works** — preflight, real backup, sandboxed trial conversion |
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| `stalwart-migrate run` | **Refuses on purpose** — see below |
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| `stalwart-migrate status <id>` | **Works** |
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| `stalwart-migrate report <id>` | Not implemented |
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**`run` without `--dry-run` deliberately refuses to proceed.** Cutover
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(ARCHITECTURE.md §4.5) is implemented and tested, but nothing calls it: the
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staging phase (§4.3) and the production pipeline that would run preflight →
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backup → stage → recovery-mode → cutover → validate against real paths don't
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exist yet. `run` stops rather than going partway. That refusal is the correct
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behaviour today, not a bug.
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Package state:
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| Package | Lines | Tests |
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| `internal/backup` | 1806 | yes |
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| `internal/preflight` | 1329 | yes |
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| `internal/stalwartapi` | 1276 | yes |
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| `internal/cutover` | 1186 | yes |
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| `internal/validate` | 792 | yes |
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| `internal/recovery` | 702 | yes |
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| `internal/checkpoint` | 556 | yes |
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| `internal/service` | 467 | yes |
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| `internal/plan` | 195 | yes |
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| `internal/config` | stub | — |
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## Why not a shell script
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Stalwart's 0.15 → 0.16 boundary is not a drop-in binary swap: settings move,
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and the data directory has to be migrated rather than merely copied. The
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failure mode that matters is a half-migrated mail store with no way back —
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which is why backup verification and checkpointing are the design centre
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rather than conveniences bolted on afterwards — and why the tool refuses to
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cut over until you confirm you have a way back.
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[`ARCHITECTURE.md`](ARCHITECTURE.md) covers this in full: §1 on why a thin
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wrapper is insufficient, §4 on the migration phases, §5 on the checkpoint
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state machine, §6 on the CLI surface, and §8 on what is still open.
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## Build and test
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```sh
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go build ./...
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go test ./...
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```
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Requires Go 1.26 or newer.
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## Trying it safely
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`preflight` is the sensible starting point — its checks against the Stalwart
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installation are read-only:
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```sh
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sudo go run ./cmd/stalwart-migrate preflight
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```
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It still needs write access, because it records the run as a checkpoint
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before doing anything else:
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```
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create run: checkpoint: create run directory:
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mkdir /var/lib/stalwart-migrator: permission denied
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```
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That path is `checkpoint.DefaultBaseDir`, a compile-time constant with no
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flag or environment override — so preflight needs either root or a
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pre-created writable `/var/lib/stalwart-migrator`. (`run` takes `--work-dir`
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for its scratch space, but that is a different directory and does not move
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the checkpoint store.)
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`run --dry-run` performs a **real backup**, which touches the live data
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directory — read the caveat the command prints before using it on anything
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you care about. Where the plan crosses the 0.15/0.16 boundary it clones that
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verified backup into a disposable sandbox and converts the copy, leaving the
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original untouched.
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## Recovery is your job
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**This tool does not undo a migration.** There is no `rollback` command.
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Recovery from a failed migration is your own snapshot or backup, taken by
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whatever method you already trust and know how to restore — a ZFS, LVM or
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btrfs snapshot, a VM or volume snapshot, or a restorable backup. Choosing
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that method, taking it, and verifying you can actually restore from it is
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out of scope for this tool: it does not take one, does not check that one
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exists, and cannot restore from one.
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Cutover refuses to start until you confirm a recovery point exists. That
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confirmation is an acknowledgement, not a check — nothing here can verify
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your snapshot. Its only purpose is that nobody migrates a production mail
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server having never been asked the question.
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**Take the snapshot with the service stopped** if you want a clean one. A
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snapshot of a running Stalwart is crash-consistent rather than clean; RocksDB
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will usually recover from its WAL, but "usually" is doing real work in that
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sentence.
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### Restoring from a snapshot loses mail delivered since
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Reverting to any pre-migration recovery point discards mail delivered
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between taking it and restoring it. This is inherent to restoring a point in
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time and this tool cannot solve it — plan your migration window with that in
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mind, and consider holding inbound mail at a secondary MX for the duration
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if the gap matters to you.
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### What the tool does to make a manual restore easier
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- **The old binary is preserved**, never deleted, next to the new one as
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`<binary>.v<old-version>` — so putting things back doesn't depend on
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re-downloading a specific old release under pressure.
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- **The original service definition is preserved** as `<unit>.pre-<run-id>`
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before cutover rewrites it, so you aren't reconstructing a unit file from
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memory.
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- **The settings and principals dumps** taken during backup stay on disk.
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- **Every artifact path and checksum is in the checkpoint**, and
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`stalwart-migrate status <run-id>` prints exactly which steps completed
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and which failed — which is the first thing you want when deciding what to
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restore.
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None of this is a substitute for the snapshot. It's what makes the twenty
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minutes after restoring one less unpleasant.
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### Why it works this way
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An earlier version of this tool implemented rollback itself: it restored the
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filesystem backup, verified every restored file against a manifest, replayed
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SQL dumps, reinstalled the old binary, and re-validated the result. It was
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tested and it looked good. It was removed, because restoring bytes correctly
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is not the hard part — it copied contents and permissions but not
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*ownership*, so run as root it would have produced a byte-perfect,
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checksum-verified, root-owned data directory that Stalwart, running as its
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own user, could not open, and it would have reported success. A filesystem
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snapshot has no such failure mode, because it never lost the metadata to
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begin with. ARCHITECTURE.md §4.8 records the full reasoning.
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