mesh-host/internal/apply/restart_order_test.go

package apply

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/novox/mesh-host/internal/store"
)

// The resolver's configuration named a second file, the mesh's zones, declared after the service —
// as a module's facts are, after its resources. The host restarted the service for the
// configuration, the daemon could not read the zones file the same apply had not written yet, and
// the apply failed on every machine (novox/hq issue 260). A service is restarted only once every
// resource it names under restart-on has been applied.
func TestAServiceIsRestartedOnlyOnceEveryFileItNamesIsWritten(t *testing.T) {
	dir := t.TempDir()
	conf := filepath.Join(dir, "resolver.conf")
	zones := filepath.Join(dir, "zones.conf")
	declare := func(zonesContent string) string {
		return fmt.Sprintf(`{"declaration":1,"resources":[
		  {"id":"resolver.config","type":"file","path":%q,"content":"conf-file=%s\n","mode":"0644"},
		  {"id":"resolver.service","type":"service","unit":"resolver.service","state":"running",
		   "restart-on":["resolver.config","resolver.fact-zones"]},
		  {"id":"resolver.fact-zones","type":"file","path":%q,"content":%q,"mode":"0644"}
		]}`, conf, zones, zones, zonesContent)
	}

	// A daemon that cannot start without both of its files, as dnsmasq cannot.
	var commands []string
	services := recordingServices(&commands)
	run := func(ctx context.Context, name string, args ...string) (string, error) {
		args = oldShape(name, args)
		if strings.Contains(strings.Join(args, " "), "start resolver.service") {
			if _, err := os.Stat(zones); err != nil {
				commands = append(commands, name+" "+strings.Join(args, " "))
				return "", errors.New("cannot read " + zones + ": no such file or directory")
			}
		}
		return services(ctx, name, args...)
	}

	report, state, err := Apply(context.Background(), archHost(t), parse(t, declare("server=/a/1\n")),
		store.State{}, store.OriginCarried, run, nil, nil)
	if err != nil {
		t.Fatalf("the service was restarted before every file it reads was written: %v", err)
	}
	var detail string
	for _, o := range report.Outcomes {
		if o.ID == "resolver.service" {
			detail = o.Detail
		}
	}
	if !strings.Contains(detail, "resolver.config") || !strings.Contains(detail, "resolver.fact-zones") {
		t.Errorf("one restart for both files was expected, the outcome says %q", detail)
	}
	restarts := 0
	for _, c := range commands {
		if strings.Contains(c, "stop resolver.service") {
			restarts++
		}
	}
	if restarts != 1 {
		t.Errorf("the service was restarted %d times; once, after both files: %v", restarts, commands)
	}

	// And a change to the file declared after the service alone is acted on in the apply that
	// makes it — not passed by because the service was reached first.
	commands = nil
	if _, _, err := Apply(context.Background(), archHost(t), parse(t, declare("server=/b/2\n")),
		state, store.OriginCarried, run, nil, nil); err != nil {
		t.Fatal(err)
	}
	restarted := false
	for _, c := range commands {
		if strings.Contains(c, "stop resolver.service") {
			restarted = true
		}
	}
	if !restarted {
		t.Errorf("the zones file changed and the service was not restarted: %v", commands)
	}
}

// Only a service moves, and only to just after the last resource it names — under restart-on or
// reload-on, in its own module or another's. Everything else keeps its declared place, and a name
// not in the declaration is no reason to move.
func TestAServiceIsOrderedAfterWhatItNamesAndNothingElseMoves(t *testing.T) {
	d := parse(t, `{"declaration":1,"resources":[
	  {"id":"a.dir","type":"directory","path":"/tmp/a"},
	  {"id":"a.runtime","type":"service","unit":"docker.service","state":"running","reload-on":["b.daemon"]},
	  {"id":"a.svc","type":"service","unit":"a.service","state":"running","restart-on":["a.conf","gone"]},
	  {"id":"a.conf","type":"file","path":"/tmp/a/conf","content":"x\n"},
	  {"id":"b.daemon","type":"file","path":"/tmp/b/daemon.json","content":"{}\n"},
	  {"id":"b.after","type":"file","path":"/tmp/b/after","content":"y\n"},
	  {"id":"b.svc","type":"service","unit":"b.service","state":"running","restart-on":["a.conf"]}
	]}`)
	var got []string
	for _, r := range afterWhatTheyRead(d.Resources) {
		got = append(got, r.Identity())
	}
	want := "a.dir a.conf a.svc b.daemon a.runtime b.after b.svc"
	if strings.Join(got, " ") != want {
		t.Errorf("ordered\n  %s\nwant\n  %s", strings.Join(got, " "), want)
	}
}