fix: wire up cron metrics (#3401)

There were a couple of metrics that no longer made sense, and we don't
have the deployment key available in the cron module, which might be a
problem.

backend/cron/observability/cron.go

@@ -19,9 +19,6 @@ const (
 	cronMeterName            = "ftl.cron"
 	cronJobFullNameAttribute = "ftl.cron.job.full_name"
 
-	cronJobKilledStatus      = "killed"
-	cronJobFailedStartStatus = "failed_start"
-
 	deploymentMeterName = "ftl.deployments.cron"
 )
 
@@ -84,24 +81,12 @@ func (m *CronMetrics) JobSuccess(ctx context.Context, job model.CronJob) {
 	m.jobCompleted(ctx, job, observability.SuccessStatus)
 }
 
-func (m *CronMetrics) JobKilled(ctx context.Context, job model.CronJob) {
-	m.jobCompleted(ctx, job, cronJobKilledStatus)
-}
-
-func (m *CronMetrics) JobFailedStart(ctx context.Context, job model.CronJob) {
-	completionAttributes := cronAttributes(job, optional.Some(cronJobFailedStartStatus))
-
-	elapsed := timeSinceMS(job.NextExecution)
-	m.jobLatency.Record(ctx, elapsed, completionAttributes)
-	m.jobsCompleted.Add(ctx, 1, completionAttributes)
-}
-
 func (m *CronMetrics) JobFailed(ctx context.Context, job model.CronJob) {
 	m.jobCompleted(ctx, job, observability.FailureStatus)
 }
 
 func (m *CronMetrics) jobCompleted(ctx context.Context, job model.CronJob, status string) {
-	elapsed := timeSinceMS(job.NextExecution)
+	elapsed := timeSinceMS(job.StartTime)
 
 	m.jobsActive.Add(ctx, -1, cronAttributes(job, optional.None[string]()))
 

backend/cron/service.go

@@ -10,10 +10,12 @@ import (
 	"github.com/jpillora/backoff"
 	"golang.org/x/sync/errgroup"
 
+	"github.com/TBD54566975/ftl/backend/cron/observability"
 	ftlv1 "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1"
 	schemapb "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/schema"
 	"github.com/TBD54566975/ftl/internal/cron"
 	"github.com/TBD54566975/ftl/internal/log"
+	"github.com/TBD54566975/ftl/internal/model"
 	"github.com/TBD54566975/ftl/internal/rpc"
 	"github.com/TBD54566975/ftl/internal/schema"
 	"github.com/TBD54566975/ftl/internal/slices"
@@ -108,8 +110,20 @@ func run(ctx context.Context, verbClient CallClient, changes chan *ftlv1.PullSch
 			cronQueue[0] = job
 			orderQueue(cronQueue)
 
+			cronModel := model.CronJob{
+				// TODO: We don't have the runner key available here.
+				Key:           model.NewCronJobKey(job.module, job.verb.Name),
+				Verb:          schema.Ref{Module: job.module, Name: job.verb.Name},
+				Schedule:      job.pattern.String(),
+				StartTime:     time.Now(),
+				NextExecution: job.next,
+			}
+			observability.Cron.JobStarted(ctx, cronModel)
 			if err := callCronJob(ctx, verbClient, job); err != nil {
+				observability.Cron.JobFailed(ctx, cronModel)
 				logger.Errorf(err, "Failed to execute cron job")
+			} else {
+				observability.Cron.JobSuccess(ctx, cronModel)
 			}
 		}
 	}