diff --git a/SPECS.md b/SPECS.md index 191b13b..5195fda 100644 --- a/SPECS.md +++ b/SPECS.md @@ -228,7 +228,7 @@ Upgrading nixpkgs (the kernel and every package) on the router, without a new re - **Setting** `router.update.channel`: `unstable` or a release like `26.05` (branch `nixos-26.05`); null: the packages that came with the installed release. Read from the saved `settings.json` when upgrading; applying settings does not change nixpkgs. - **`router-upgrade check`**: the branch's newest revision from `//git-revision` (a redirect to releases.nixos.org, so curl follows it; the last revision Hydra's tests passed), against the running one (`nixos-version --revision`). Writes `/var/lib/router/upgrade/check.json`. -- **`preview [--force]`**: locks a copy of the configuration flake to that revision (`nix flake lock --override-input nixos-router/nixpkgs`), evaluates it and lists the packages of the running system that have another version in the new system's derivations, how much `nix build --dry-run` would download, and how many derivations would be built here. Nothing is downloaded: evaluation fetches the nixpkgs source only. Approximate: a rebuild without a new version is not listed. Refuses a NixOS release older than the running one. A changed `linux` sets `rebootNeeded`. Result in `preview.json`. +- **`preview [--force] [--downgrade]`**: locks a copy of the configuration flake to that revision (`nix flake lock --override-input nixos-router/nixpkgs`), evaluates it and lists the packages of the running system that have another version in the new system's derivations, how much `nix build --dry-run` would download, and how many derivations would be built here. Nothing is downloaded: evaluation fetches the nixpkgs source only. Approximate: a rebuild without a new version is not listed. Refuses a NixOS release older than the running one (unstable calls itself 26.11, so following 26.05 from unstable is one) unless `--downgrade` (the page's "downgrade anyway") is given; it then warns that state written by the newer release may not work. Not exercised in a VM test: the test's nixpkgs copy has the same release. A changed `linux` sets `rebootNeeded`. Result in `preview.json`. - **`download`**: fetches and builds it (needs 3 GiB free), so a flaky uplink does not matter at `apply`. - **`apply [timeout]`**: takes the previewed lock into the configuration directory and runs `router-apply` (commit-confirm). The directory as it was is kept in `config.pre-update` like for updates: a rollback or a failed build puts the lock back. Refused if the configuration flake changed since the preview. - **Pin**: `nixpkgs-pin.json` in the configuration directory (channel, revision, flake reference with `narHash`). `router-update` locks it again after it installs a new release of nixos-router, so a release does not undo an upgrade; the reference is found in the store by its hash, offline. diff --git a/modules/settings/upgrade.nix b/modules/settings/upgrade.nix index 73f1a32..c049255 100644 --- a/modules/settings/upgrade.nix +++ b/modules/settings/upgrade.nix @@ -41,7 +41,7 @@ let ]; text = '' usage() { - echo "usage: router-upgrade check | preview [--force] | download | apply [timeout] | --request" >&2 + echo "usage: router-upgrade check | preview [--force] [--downgrade] | download | apply [timeout] | --request" >&2 echo " check the newest revision of router.update.channel, against the running one" >&2 echo " preview the packages that change and the size of the download (nothing is fetched)" >&2 echo " download fetch and build what was previewed, without activating it" >&2 @@ -56,12 +56,13 @@ let [ -r "$req" ] || die "no request" action=$(jq -er .action "$req") force=$(jq -r 'if .force then "--force" else "" end' "$req") + downgrade=$(jq -r 'if .downgrade then "--downgrade" else "" end' "$req") timeout=$(jq -r '.timeout // ""' "$req") rm -f "$req" # The web UI shows the last run (a finished unit forgets its journal). exec > >(tee ${dir}/last.log) 2>&1 case $action in - preview) set -- preview ''${force:+"$force"} ;; + preview) set -- preview ''${force:+"$force"} ''${downgrade:+"$downgrade"} ;; apply) set -- apply ''${timeout:+"$timeout"} ;; check | download) set -- "$action" ;; *) die "unknown request: $action" ;; @@ -127,8 +128,14 @@ let } preview() { - local force=0 - [ "''${1:-}" != --force ] || force=1 + local force=0 downgrade=0 arg + for arg in "$@"; do + case $arg in + --force) force=1 ;; + --downgrade) downgrade=1 ;; + *) usage ;; + esac + done check rm -rf ${dir}/preview.json ${dir}/flake ${dir}/result if [ "$same" = true ] && [ "$force" -eq 0 ]; then return 0; fi @@ -155,8 +162,11 @@ let # The release (26.05) of a version like 26.05.20260101.abcdef0 or 26.11pre-git. release() { sed -E 's/^([0-9]+\.[0-9]+).*/\1/' <<<"$1"; } newer=$(printf '%s\n%s\n' "$(release "$new_version")" "$(release "$running_version")" | sort -V | tail -1) - [ "$newer" = "$(release "$new_version")" ] \ - || die "$new_version is older than the running $running_version: NixOS cannot be downgraded" + if [ "$newer" != "$(release "$new_version")" ]; then + [ "$downgrade" -eq 1 ] \ + || die "$new_version is older than the running $running_version: NixOS cannot be downgraded safely (use --downgrade to try anyway)" + echo "router-upgrade: warning: $new_version is older than the running $running_version; state written by the newer release may not work with it" + fi drv=$(nix eval --raw "$attr.build.toplevel.drvPath") nix path-info -r /run/current-system | names > ${dir}/old.names diff --git a/pkgs/router-webui/templates/upgrade.html b/pkgs/router-webui/templates/upgrade.html index 6200e08..3f3f008 100644 --- a/pkgs/router-webui/templates/upgrade.html +++ b/pkgs/router-webui/templates/upgrade.html @@ -18,8 +18,9 @@ -

The channel only chooses what an upgrade offers; saving it changes nothing on the router. NixOS cannot go back to - an older release.

+

The channel only chooses what an upgrade offers; saving it changes nothing on the router. Going back to an older release + (unstable to 26.05) is refused unless you tick "downgrade anyway" when previewing; state written by the newer + release may not work with the older one.

{{if $d.Updating}} @@ -54,6 +55,7 @@
{{if and $d.Check $d.Check.UpToDate}}{{end}} +

Works it out from the new revision's description: no package is downloaded.

diff --git a/pkgs/router-webui/upgrade.go b/pkgs/router-webui/upgrade.go index da12ece..bfcb259 100644 --- a/pkgs/router-webui/upgrade.go +++ b/pkgs/router-webui/upgrade.go @@ -121,8 +121,8 @@ type UpgradeRun = UpdateStatus func (s System) UpgradeStatus() UpgradeRun { return unitRun("router-upgrade.service") } // requestUpgrade asks the router-upgrade unit for one step. -func (s System) requestUpgrade(action string, force bool, timeout string) error { - data, _ := json.Marshal(map[string]any{"action": action, "force": force, "timeout": timeout}) +func (s System) requestUpgrade(action string, force, downgrade bool, timeout string) error { + data, _ := json.Marshal(map[string]any{"action": action, "force": force, "downgrade": downgrade, "timeout": timeout}) if err := os.MkdirAll(s.upgradeDir(), 0o700); err != nil { return err } @@ -254,7 +254,7 @@ func (a *app) upgradeStep(w http.ResponseWriter, r *http.Request, _ session) { a.upgradeBack(w, r, "Preview first: it says what would change.") return } - if err := a.sys.requestUpgrade(action, r.PostFormValue("force") == "on", ""); err != nil { + if err := a.sys.requestUpgrade(action, r.PostFormValue("force") == "on", r.PostFormValue("downgrade") == "on", ""); err != nil { a.upgradeBack(w, r, fmt.Sprintf("Could not start it: %v", err)) return } diff --git a/pkgs/router-webui/upgrade_test.go b/pkgs/router-webui/upgrade_test.go index ac41d24..726e811 100644 --- a/pkgs/router-webui/upgrade_test.go +++ b/pkgs/router-webui/upgrade_test.go @@ -135,8 +135,8 @@ func TestUpgradePage(t *testing.T) { if r := request(); r["action"] != "check" || started != 1 { t.Fatalf("%v started %d", r, started) } - post("/upgrade/preview", url.Values{"force": {"on"}}) - if r := request(); r["action"] != "preview" || r["force"] != true { + post("/upgrade/preview", url.Values{"force": {"on"}, "downgrade": {"on"}}) + if r := request(); r["action"] != "preview" || r["force"] != true || r["downgrade"] != true { t.Fatalf("%v", r) } if resp := post("/upgrade/format-disk", url.Values{}); resp.StatusCode != http.StatusNotFound {