Alerting: Delete expired images from the database (#53236)

This commit adds a DeleteExpiredService that deletes expired images from the database. It is run in the periodic collector service.

pkg/services/ngalert/models/image.go

@@ -5,8 +5,10 @@ import (
 	"time"
 )
 
-// ErrImageNotFound is returned when the image does not exist.
-var ErrImageNotFound = errors.New("image not found")
+var (
+	// ErrImageNotFound is returned when the image does not exist.
+	ErrImageNotFound = errors.New("image not found")
+)
 
 type Image struct {
 	ID        int64     `xorm:"pk autoincr 'id'"`
@@ -17,6 +19,27 @@ type Image struct {
 	ExpiresAt time.Time `xorm:"expires_at"`
 }
 
+// ExtendDuration extends the expiration time of the image. It can shorten
+// the duration of the image if d is negative.
+func (i *Image) ExtendDuration(d time.Duration) {
+	i.ExpiresAt = i.ExpiresAt.Add(d)
+}
+
+// HasExpired returns true if the image has expired.
+func (i *Image) HasExpired() bool {
+	return time.Now().After(i.ExpiresAt)
+}
+
+// HasPath returns true if the image has a path on disk.
+func (i *Image) HasPath() bool {
+	return i.Path != ""
+}
+
+// HasURL returns true if the image has a URL.
+func (i *Image) HasURL() bool {
+	return i.URL != ""
+}
+
 // A XORM interface that defines the used table for this struct.
 func (i *Image) TableName() string {
 	return "alert_image"

pkg/services/ngalert/models/image_test.go

@@ -0,0 +1,48 @@
+package models
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestImage_ExtendDuration(t *testing.T) {
+	var i Image
+	d := time.Now().Add(time.Minute)
+	i.ExpiresAt = d
+	// extend the duration for 1 minute
+	i.ExtendDuration(time.Minute)
+	assert.Equal(t, d.Add(time.Minute), i.ExpiresAt)
+	// can shorten the duration too
+	i.ExtendDuration(-time.Minute)
+	assert.Equal(t, d, i.ExpiresAt)
+}
+
+func TestImage_HasExpired(t *testing.T) {
+	var i Image
+	i.ExpiresAt = time.Now().Add(time.Minute)
+	assert.False(t, i.HasExpired())
+	i.ExpiresAt = time.Now()
+	assert.True(t, i.HasExpired())
+	i.ExpiresAt = time.Now().Add(-time.Minute)
+	assert.True(t, i.HasExpired())
+}
+
+func TestImage_HasPath(t *testing.T) {
+	var i Image
+	assert.False(t, i.HasPath())
+	i.Path = "/"
+	assert.True(t, i.HasPath())
+	i.Path = "/tmp/image.png"
+	assert.True(t, i.HasPath())
+}
+
+func TestImage_HasURL(t *testing.T) {
+	var i Image
+	assert.False(t, i.HasURL())
+	i.URL = "/"
+	assert.True(t, i.HasURL())
+	i.URL = "https://example.com/image.png"
+	assert.True(t, i.HasURL())
+}