fix(events): refuse a retention below one day

A retention of zero or less moved the delete cutoff to now or later. The cleaner then deleted all event history. The cleaner now refuses to start and returns an error.

events.go

@@ -12,6 +12,9 @@ import (
 const (
 	initialDelay    = 60 * time.Second
 	cleanupInterval = 1 * time.Hour
+
+	// minRetentionDays guards against a cutoff at or after NOW(), which would delete all event history.
+	minRetentionDays = 1
 )
 
 // Use parameterized queries to prevent SQL injection
@@ -46,6 +49,10 @@ func enableHasuraEventCleaner(ctx context.Context) error {
 	logger := cfg.Logger
 	cfgMutex.RUnlock()
 
+	if clearOlderThan < minRetentionDays {
+		return fmt.Errorf("HASURA_EVENT_CLEANER_OLDER_THAN must be at least %d day, got %d: event cleaner not started", minRetentionDays, clearOlderThan)
+	}
+
 	logger.Info(&libpack_logger.LogMessage{
 		Message: "Event cleaner enabled",
 		Pairs:   map[string]any{"interval_in_days": clearOlderThan},

events_retention_test.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"context"
+	"testing"
+
+	libpack_logger "github.com/lukaszraczylo/graphql-monitoring-proxy/logging"
+	"github.com/stretchr/testify/assert"
+)
+
+// Pins theorems/Theorems/EventCleaner.lean: a retention below one day would delete all event history.
+func TestEnableHasuraEventCleaner_RejectsNonPositiveRetention(t *testing.T) {
+	for _, days := range []int{0, -1, -30} {
+		cfgMutex.Lock()
+		cfg = &config{Logger: libpack_logger.New()}
+		cfg.HasuraEventCleaner.Enable = true
+		cfg.HasuraEventCleaner.EventMetadataDb = "postgres://fake:[email protected]:1/fake"
+		cfg.HasuraEventCleaner.ClearOlderThan = days
+		cfgMutex.Unlock()
+
+		ctx, cancel := context.WithCancel(context.Background())
+		err := enableHasuraEventCleaner(ctx)
+		cancel()
+		assert.Error(t, err, "days=%d", days)
+	}
+}