Add imagetag filter based on kayml libraries

api/image/image.go

@@ -0,0 +1,50 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package image
+
+import (
+	"regexp"
+	"strings"
+)
+
+// IsImageMatched returns true if the value of t is identical to the
+// image name in the full image name and tag as given by s.
+func IsImageMatched(s, t string) bool {
+	// Tag values are limited to [a-zA-Z0-9_.{}-].
+	// Some tools like Bazel rules_k8s allow tag patterns with {} characters.
+	// More info: https://github.com/bazelbuild/rules_k8s/pull/423
+	pattern, _ := regexp.Compile("^" + t + "(@sha256)?(:[a-zA-Z0-9_.{}-]*)?$")
+	return pattern.MatchString(s)
+}
+
+// Split separates and returns the name and tag parts
+// from the image string using either colon `:` or at `@` separators.
+// Note that the returned tag keeps its separator.
+func Split(imageName string) (name string, tag string) {
+	// check if image name contains a domain
+	// if domain is present, ignore domain and check for `:`
+	ic := -1
+	if slashIndex := strings.Index(imageName, "/"); slashIndex < 0 {
+		ic = strings.LastIndex(imageName, ":")
+	} else {
+		lastIc := strings.LastIndex(imageName[slashIndex:], ":")
+		// set ic only if `:` is present
+		if lastIc > 0 {
+			ic = slashIndex + lastIc
+		}
+	}
+	ia := strings.LastIndex(imageName, "@")
+	if ic < 0 && ia < 0 {
+		return imageName, ""
+	}
+
+	i := ic
+	if ia > 0 {
+		i = ia
+	}
+
+	name = imageName[:i]
+	tag = imageName[i:]
+	return
+}

api/image/image_test.go

@@ -0,0 +1,80 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package image
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsImageMatched(t *testing.T) {
+	testCases := []struct {
+		testName  string
+		value     string
+		name      string
+		isMatched bool
+	}{
+		{
+			testName:  "identical",
+			value:     "nginx",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is match",
+			value:     "nginx:12345",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is not a match",
+			value:     "apache:12345",
+			name:      "nginx",
+			isMatched: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.testName, func(t *testing.T) {
+			assert.Equal(t, tc.isMatched, IsImageMatched(tc.value, tc.name))
+		})
+	}
+}
+
+func TestSplit(t *testing.T) {
+	testCases := []struct {
+		testName string
+		value    string
+		name     string
+		tag      string
+	}{
+		{
+			testName: "no tag",
+			value:    "nginx",
+			name:     "nginx",
+			tag:      "",
+		},
+		{
+			testName: "with tag",
+			value:    "nginx:1.2.3",
+			name:     "nginx",
+			tag:      ":1.2.3",
+		},
+		{
+			testName: "with digest",
+			value:    "nginx@12345",
+			name:     "nginx",
+			tag:      "@12345",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.testName, func(t *testing.T) {
+			name, tag := Split(tc.value)
+			assert.Equal(t, tc.name, name)
+			assert.Equal(t, tc.tag, tag)
+		})
+	}
+}