feat(master): check the registry now from the service page (#35)

internal/master/poller/poller.go

@@ -139,6 +139,17 @@ func (p *Poller) Cycle(ctx context.Context) {
 		p.log.Error("poll_list_failed", "error", err)
 		return
 	}
+	stats := p.pollServices(ctx, svcs)
+	p.log.Info("poll_cycle", "refs", stats.refs, "ok", stats.ok, "failed", stats.failed,
+		"suggested", stats.suggested, "jobs", stats.jobs, "skipped", stats.skipped,
+		"repos_listed", stats.reposListed, "tags_failed", stats.tagsFailed, "newer", stats.newer,
+		"duration_ms", p.now().Sub(began).Milliseconds())
+}
+
+// pollServices does the work of a cycle for svcs: it looks up every distinct
+// followed ref once, records the results and starts auto jobs, then syncs the
+// newer-tag suggestions of svcs.
+func (p *Poller) pollServices(ctx context.Context, svcs []model.Service) cycleStats {
 	var stats cycleStats
 	byRef := map[string][]model.Service{}
 	var refs []string
@@ -170,10 +181,41 @@ func (p *Poller) Cycle(ctx context.Context) {
 	p.publishIfWrote(&stats)
 	p.syncNewer(ctx, write, svcs, &stats)
 	p.publishIfWrote(&stats)
-	p.log.Info("poll_cycle", "refs", stats.refs, "ok", stats.ok, "failed", stats.failed,
-		"suggested", stats.suggested, "jobs", stats.jobs, "skipped", stats.skipped,
-		"repos_listed", stats.reposListed, "tags_failed", stats.tagsFailed, "newer", stats.newer,
+	return stats
+}
+
+// NotPolledError says a service cannot be checked against the registry.
+type NotPolledError struct{ Reason string }
+
+func (e *NotPolledError) Error() string { return "not polled: " + e.Reason }
+
+// PollService does what Cycle does, for the service id only: it looks up the
+// followed ref, records the digest, starts an auto job if one is wanted and
+// syncs the newer-tag suggestion. Other services that follow the same ref are
+// updated at the next cycle. It is safe to run while Run is running: the
+// unique index update_jobs_one_active prevents duplicate jobs. A registry
+// error is not returned; it is stored as last_poll_error, like in a cycle. It
+// returns the store's error when the service cannot be read, model.ErrNotFound
+// for a removed service, *NotPolledError when the service is not polled, and
+// ctx.Err() when ctx ended.
+func (p *Poller) PollService(ctx context.Context, id int64) error {
+	began := p.now()
+	svc, err := p.store.GetService(ctx, id)
+	if err != nil {
+		return err
+	}
+	if svc.RemovedAt != nil {
+		return model.ErrNotFound
+	}
+	if r := SkipReason(svc); r != "" {
+		return &NotPolledError{Reason: r}
+	}
+	stats := p.pollServices(ctx, []model.Service{svc})
+	p.log.Info("poll_service", "service_id", id, "ref", jobs.FollowedRef(svc.ActualRef),
+		"ok", stats.ok, "failed", stats.failed, "suggested", stats.suggested, "jobs", stats.jobs,
+		"tags_failed", stats.tagsFailed, "newer", stats.newer,
 		"duration_ms", p.now().Sub(began).Milliseconds())
+	return ctx.Err()
 }
 
 // publishIfWrote tells the browsers to refresh if a phase of the cycle wrote