mesh-catalog/modules/restic/cmd/restic-backups/retention_test.go

package main

// The retention is a preference (novox/hq issue 416, ADR 0262): the mesh writes the keep-daily,
// keep-weekly and keep-monthly settings into a file in this module's state, and a night thins the
// restore points by what that file says. A value that is not a count thins nothing.

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
	"time"
)

// thinning runs one night over a fake restic and answers the forget line it ran ("" when none) and
// what the module said.
func thinning(t *testing.T, retention *string) (string, []string) {
	t.Helper()
	where := placed(t, "# pg\npath /\n")
	path := filepath.Join(where.State, RetentionFile)
	if retention != nil {
		must(t, os.WriteFile(path, []byte(*retention), 0o600))
	} else {
		must(t, os.Remove(path))
	}
	forget := ""
	run := func(_ context.Context, name string, args ...string) (string, error) {
		if name == "restic" && args[5] == "forget" {
			forget = "restic " + strings.Join(args[5:], " ")
		}
		if name == "restic" && args[5] == "backup" {
			return "{\"message_type\":\"summary\",\"snapshot_id\":\"abcdef0123456789\"}\n", nil
		}
		return "", nil
	}
	var said []string
	say := func(format string, args ...any) { said = append(said, fmt.Sprintf(format, args...)) }
	b := &Backups{Where: where, Run: run, Now: func() time.Time { return time.Date(2026, 10, 11, 3, 0, 0, 0, time.UTC) }, Say: say}
	outcome, err := b.BackUp(context.Background(), "")
	must(t, err)
	if !outcome["pg"].OK {
		t.Fatalf("the night itself failed: %+v", outcome["pg"])
	}
	return forget, said
}

func TestANightThinsByTheRetentionTheMeshWrote(t *testing.T) {
	conf := "# Written by the mesh.\ndaily=7\nweekly=4\nmonthly=24\n"
	got, _ := thinning(t, &conf)
	if want := "restic forget --prune --group-by host,tags --keep-daily 7 --keep-weekly 4 --keep-monthly 24"; got != want {
		t.Errorf("ran %q, want %q", got, want)
	}
}

// Every machine has had the file since mesh-catalog #200 rolled out (novox/hq issue 454), so a missing one is
// a fault, never a reason to thin by 14/8/6: a lost file would otherwise thin by a number nobody set.
func TestWithoutTheFileANightThinsNothingAndSaysTheFileIsMissing(t *testing.T) {
	got, said := thinning(t, nil)
	if got != "" {
		t.Errorf("ran %q without a retention file", got)
	}
	all := strings.Join(said, "\n")
	if !strings.Contains(all, "retention.conf is missing") || !strings.Contains(all, "every restore point is kept") {
		t.Errorf("said %q, want it to say the file is missing and every restore point is kept", all)
	}
}

// The mesh writes the file as root's alone (a trusted file, novox/hq issue 339), and the night runs as the
// operator account: what the account cannot read is read as root, as every other root's file here is
// (novox/hq issue 454). Before, every machine's night refused it as unreadable and thinned nothing.
func TestARetentionOnlyRootMayReadIsReadAsRoot(t *testing.T) {
	where := placed(t, "# pg\npath /\n")
	path := filepath.Join(where.State, RetentionFile)
	must(t, os.WriteFile(path, []byte("daily=7\nweekly=4\nmonthly=24\n"), 0o600))
	must(t, os.Chmod(path, 0))
	if os.Getuid() == 0 {
		t.Skip("root reads a file of mode 0 itself; nothing to escalate")
	}
	forget, catted := "", ""
	run := func(_ context.Context, name string, args ...string) (string, error) {
		switch {
		case name == "cat":
			catted = strings.Join(args, " ")
			return "daily=7\nweekly=4\nmonthly=24\n", nil
		case name == "restic" && args[5] == "forget":
			forget = "restic " + strings.Join(args[5:], " ")
		case name == "restic" && args[5] == "backup":
			return "{\"message_type\":\"summary\",\"snapshot_id\":\"abcdef0123456789\"}\n", nil
		}
		return "", nil
	}
	b := &Backups{Where: where, Run: run, Now: time.Now, Say: quiet}
	_, err := b.BackUp(context.Background(), "")
	must(t, err)
	if catted != "-- "+path {
		t.Errorf("read %q as root, want %q", catted, "-- "+path)
	}
	if want := "restic forget --prune --group-by host,tags --keep-daily 7 --keep-weekly 4 --keep-monthly 24"; forget != want {
		t.Errorf("ran %q, want %q", forget, want)
	}
}

// A value that is not a count from 1 to 9999 is never handed to restic: nothing is thinned, every
// restore point is kept, and the module says which setting is wrong (issue 346: a raw setting is an
// injection point).
func TestARetentionThatIsNotACountThinsNothingAndSaysWhich(t *testing.T) {
	for _, c := range []struct{ conf, names string }{
		{"daily=0\nweekly=8\nmonthly=6\n", "keep-daily"},
		{"daily=14\nweekly=-1\nmonthly=6\n", "keep-weekly"},
		{"daily=14\nweekly=8\nmonthly=6 --keep-last 1\n", "keep-monthly"},
		{"daily=14\nweekly=8\nmonthly=10000\n", "keep-monthly"},
		{"daily=fourteen\nweekly=8\nmonthly=6\n", "keep-daily"},
		{"daily=\nweekly=8\nmonthly=6\n", "keep-daily"},
		{"daily=014\nweekly=8\nmonthly=6\n", "keep-daily"},
		{"weekly=8\nmonthly=6\n", "keep-daily"},
		{"daily=14\nweekly=8\nmonthly=6\nlast=1\n", "last"},
		{"daily=14\ndaily=3\nweekly=8\nmonthly=6\n", "daily"},
		{"daily 14\nweekly=8\nmonthly=6\n", "key=value"},
	} {
		got, said := thinning(t, &c.conf)
		if got != "" {
			t.Errorf("%q: ran %q", c.conf, got)
		}
		all := strings.Join(said, "\n")
		if !strings.Contains(all, c.names) || !strings.Contains(all, "every restore point is kept") {
			t.Errorf("%q: said %q, want it to name %s and say every restore point is kept", c.conf, all, c.names)
		}
	}
}

// The manifest declares the three preferences with today's values as their defaults, and its file,
// filled with those defaults, reads as today's retention: nothing changes on a machine that sets none.
func TestTheManifestsDefaultsAreTodaysRetention(t *testing.T) {
	raw, err := os.ReadFile("../../module.json")
	must(t, err)
	var m struct {
		Settings map[string]struct {
			Kind    string `json:"kind"`
			Default any    `json:"default"`
			Why     string `json:"why"`
		} `json:"settings"`
		Resources []map[string]any `json:"resources"`
	}
	must(t, json.Unmarshal(raw, &m))
	want := map[string]float64{"keep-daily": 14, "keep-weekly": 8, "keep-monthly": 6}
	for k, v := range want {
		s, ok := m.Settings[k]
		if !ok || s.Kind != "preference" || s.Default != v || s.Why == "" {
			t.Errorf("setting %s: %+v, want a preference defaulting to %v with why", k, s, v)
		}
	}
	content := ""
	for _, r := range m.Resources {
		if r["id"] == "retention" {
			if r["path"] != "${dir:state}/"+RetentionFile {
				t.Errorf("the retention file is placed at %v, where this program does not read it", r["path"])
			}
			content, _ = r["content"].(string)
		}
	}
	if content == "" {
		t.Fatal("no retention resource in the manifest")
	}
	filled := regexp.MustCompile(`\$\{setting:([a-z-]+)\}`).ReplaceAllStringFunc(content, func(p string) string {
		k := p[len("${setting:") : len(p)-1]
		return fmt.Sprint(m.Settings[k].Default)
	})
	got, err := ParseRetention(filled)
	must(t, err)
	if got != TodaysRetention {
		t.Errorf("the defaults read as %+v, today is %+v", got, TodaysRetention)
	}
}