refactor: Add registry pkg registry scanner (#933)

Signed-off-by: Ishita Sequeira <ishiseq29@gmail.com>

3 files changed, 164 insertions, 0 deletions

diff --git a/registry-scanner/pkg/cache/cache.go b/registry-scanner/pkg/cache/cache.go
new file mode 100644
index 0000000..1ceef66
--- /dev/null
+++ b/registry-scanner/pkg/cache/cache.go
@@ -0,0 +1,20 @@
+package cache
+
+import (
+	"github.com/argoproj-labs/argocd-image-updater/registry-scanner/pkg/tag"
+)
+
+type ImageTagCache interface {
+	HasTag(imageName string, imageTag string) bool
+	GetTag(imageName string, imageTag string) (*tag.ImageTag, error)
+	SetTag(imageName string, imgTag *tag.ImageTag)
+	ClearCache()
+	NumEntries() int
+}
+
+// KnownImage represents a known image and the applications using it, without
+// any version/tag information.
+type KnownImage struct {
+	ImageName string
+	// Applications []string
+}
diff --git a/registry-scanner/pkg/cache/memcache.go b/registry-scanner/pkg/cache/memcache.go
new file mode 100644
index 0000000..03b4080
--- /dev/null
+++ b/registry-scanner/pkg/cache/memcache.go
@@ -0,0 +1,74 @@
+package cache
+
+import (
+	"fmt"
+
+	"github.com/argoproj-labs/argocd-image-updater/registry-scanner/pkg/tag"
+
+	memcache "github.com/patrickmn/go-cache"
+)
+
+type MemCache struct {
+	cache *memcache.Cache
+}
+
+// NewMemCache returns a new instance of MemCache
+func NewMemCache() ImageTagCache {
+	mc := MemCache{}
+	c := memcache.New(0, 0)
+	mc.cache = c
+	return &mc
+}
+
+// HasTag returns true if cache has entry for given tag, false if not
+func (mc *MemCache) HasTag(imageName string, tagName string) bool {
+	tag, err := mc.GetTag(imageName, tagName)
+	if err != nil || tag == nil {
+		return false
+	} else {
+		return true
+	}
+}
+
+// SetTag sets a tag entry into the cache
+func (mc *MemCache) SetTag(imageName string, imgTag *tag.ImageTag) {
+	mc.cache.Set(tagCacheKey(imageName, imgTag.TagName), *imgTag, -1)
+}
+
+// GetTag gets a tag entry from the cache
+func (mc *MemCache) GetTag(imageName string, tagName string) (*tag.ImageTag, error) {
+	var imgTag tag.ImageTag
+	e, ok := mc.cache.Get(tagCacheKey(imageName, tagName))
+	if !ok {
+		return nil, nil
+	}
+	imgTag, ok = e.(tag.ImageTag)
+	if !ok {
+		return nil, fmt.Errorf("")
+	}
+	return &imgTag, nil
+}
+
+func (mc *MemCache) SetImage(imageName, application string) {
+	mc.cache.Set(imageCacheKey(imageName), application, -1)
+}
+
+// ClearCache clears the cache
+func (mc *MemCache) ClearCache() {
+	for k := range mc.cache.Items() {
+		mc.cache.Delete(k)
+	}
+}
+
+// NumEntries returns the number of entries in the cache
+func (mc *MemCache) NumEntries() int {
+	return mc.cache.ItemCount()
+}
+
+func tagCacheKey(imageName, imageTag string) string {
+	return fmt.Sprintf("tags:%s:%s", imageName, imageTag)
+}
+
+func imageCacheKey(imageName string) string {
+	return fmt.Sprintf("image:%s", imageName)
+}
diff --git a/registry-scanner/pkg/cache/memcache_test.go b/registry-scanner/pkg/cache/memcache_test.go
new file mode 100644
index 0000000..8fcb47b
--- /dev/null
+++ b/registry-scanner/pkg/cache/memcache_test.go
@@ -0,0 +1,70 @@
+package cache
+
+import (
+	"testing"
+	"time"
+
+	memcache "github.com/patrickmn/go-cache"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/argoproj-labs/argocd-image-updater/pkg/tag"
+)
+
+func Test_MemCache(t *testing.T) {
+	imageName := "foo/bar"
+	imageTag := "v1.0.0"
+	t.Run("Cache hit", func(t *testing.T) {
+		mc := NewMemCache()
+		newTag := tag.NewImageTag(imageTag, time.Unix(0, 0), "")
+		mc.SetTag(imageName, newTag)
+		cachedTag, err := mc.GetTag(imageName, imageTag)
+		require.NoError(t, err)
+		require.NotNil(t, cachedTag)
+		assert.Equal(t, imageTag, cachedTag.TagName)
+		assert.True(t, mc.HasTag(imageName, imageTag))
+		assert.Equal(t, 1, mc.NumEntries())
+	})
+
+	t.Run("Cache miss", func(t *testing.T) {
+		mc := NewMemCache()
+		newTag := tag.NewImageTag(imageTag, time.Unix(0, 0), "")
+		mc.SetTag(imageName, newTag)
+		assert.Equal(t, 1, mc.NumEntries())
+		cachedTag, err := mc.GetTag(imageName, "v1.0.1")
+		require.NoError(t, err)
+		require.Nil(t, cachedTag)
+		assert.False(t, mc.HasTag(imageName, "v1.0.1"))
+	})
+
+	t.Run("Cache clear", func(t *testing.T) {
+		mc := NewMemCache()
+		newTag := tag.NewImageTag(imageTag, time.Unix(0, 0), "")
+		mc.SetTag(imageName, newTag)
+		cachedTag, err := mc.GetTag(imageName, imageTag)
+		require.NoError(t, err)
+		require.NotNil(t, cachedTag)
+		assert.Equal(t, imageTag, cachedTag.TagName)
+		assert.True(t, mc.HasTag(imageName, imageTag))
+		assert.Equal(t, 1, mc.NumEntries())
+		mc.ClearCache()
+		assert.Equal(t, 0, mc.NumEntries())
+		cachedTag, err = mc.GetTag(imageName, imageTag)
+		require.NoError(t, err)
+		require.Nil(t, cachedTag)
+	})
+	t.Run("Image Cache Key", func(t *testing.T) {
+		mc := MemCache{
+			cache: memcache.New(0, 0),
+		}
+		application := "application1"
+		key := imageCacheKey(imageName)
+		mc.SetImage(imageName, application)
+		app, b := mc.cache.Get(key)
+		assert.True(t, b)
+		assert.Equal(t, application, app)
+		assert.Equal(t, 1, mc.NumEntries())
+		mc.ClearCache()
+		assert.Equal(t, 0, mc.NumEntries())
+	})
+}