Add crane-based methods for extraction

- create a new api package to encapsulate image manipulation
- use new api method to calculate delta

Fixes #258
Fixes #204
Fixes #90

pkg/api/core/image/delta_test.go

@@ -0,0 +1,136 @@
+// Copyright © 2021 Ettore Di Giacinto <mudler@gentoo.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package image_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	daemon "github.com/google/go-containerregistry/pkg/v1/daemon"
+	. "github.com/mudler/luet/pkg/api/core/image"
+	"github.com/mudler/luet/pkg/api/core/types"
+	"github.com/mudler/luet/pkg/helpers/file"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("DeltaInfo", func() {
+	Context("Generates deltas of images", func() {
+		It("Correctly detect packages", func() {
+			ref, err := name.ParseReference("alpine")
+			Expect(err).ToNot(HaveOccurred())
+
+			img, err := daemon.Image(ref)
+			Expect(err).ToNot(HaveOccurred())
+
+			layers, err := Delta(img, img)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(len(layers.Changes)).To(Equal(0))
+			Expect(len(layers.Additions)).To(Equal(0))
+			Expect(len(layers.Deletions)).To(Equal(0))
+		})
+
+		Context("ExtractDeltaFiles", func() {
+			ctx := types.NewContext()
+			var tmpfile *os.File
+			var ref, ref2 name.Reference
+			var img, img2 v1.Image
+			var diff ImageDiff
+			var err error
+
+			BeforeEach(func() {
+				ctx = types.NewContext()
+
+				tmpfile, err = ioutil.TempFile("", "delta")
+				Expect(err).ToNot(HaveOccurred())
+				defer os.RemoveAll(tmpfile.Name()) // clean up
+
+				ref, err = name.ParseReference("alpine")
+				Expect(err).ToNot(HaveOccurred())
+
+				ref2, err = name.ParseReference("golang:alpine")
+				Expect(err).ToNot(HaveOccurred())
+
+				img, err = daemon.Image(ref)
+				Expect(err).ToNot(HaveOccurred())
+				img2, err = daemon.Image(ref2)
+				Expect(err).ToNot(HaveOccurred())
+
+				diff, err = Delta(img, img2)
+				Expect(err).ToNot(HaveOccurred())
+
+				Expect(len(diff.Additions) > 0).To(BeTrue())
+				Expect(len(diff.Changes) > 0).To(BeTrue())
+				Expect(len(diff.Deletions) > 0).To(BeTrue())
+			})
+
+			It("Extract all deltas", func() {
+				tmpdir, err := Extract(
+					ctx,
+					img2,
+					ExtractDeltaFiles(ctx, diff, []string{}, []string{}),
+				)
+				Expect(err).ToNot(HaveOccurred())
+				defer os.RemoveAll(tmpdir) // clean up
+
+				fmt.Println(file.ListDir(tmpdir))
+				Expect(file.Exists(filepath.Join(tmpdir, "root", ".cache"))).To(BeTrue())
+				Expect(file.Exists(filepath.Join(tmpdir, "bin", "sh"))).To(BeFalse())
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go"))).To(BeTrue())
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go", "bin"))).To(BeTrue())
+			})
+
+			It("Extract deltas and excludes stuff", func() {
+				tmpdir, err := Extract(
+					ctx,
+					img2,
+					ExtractDeltaFiles(ctx, diff, []string{}, []string{"usr/local/go"}),
+				)
+				Expect(err).ToNot(HaveOccurred())
+				defer os.RemoveAll(tmpdir) // clean up
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go"))).To(BeFalse())
+			})
+			It("Extract deltas and excludes stuff", func() {
+				tmpdir, err := Extract(
+					ctx,
+					img2,
+					ExtractDeltaFiles(ctx, diff, []string{"usr/local/go"}, []string{"usr/local/go/bin"}),
+				)
+				Expect(err).ToNot(HaveOccurred())
+				defer os.RemoveAll(tmpdir) // clean up
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go"))).To(BeTrue())
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go", "bin"))).To(BeFalse())
+			})
+
+			It("Extract deltas and excludes stuff", func() {
+				tmpdir, err := Extract(
+					ctx,
+					img2,
+					ExtractDeltaFiles(ctx, diff, []string{"usr/local/go"}, []string{}),
+				)
+				Expect(err).ToNot(HaveOccurred())
+				defer os.RemoveAll(tmpdir) // clean up
+
+				Expect(file.Exists(filepath.Join(tmpdir, "usr", "local", "go"))).To(BeTrue())
+				Expect(file.Exists(filepath.Join(tmpdir, "root", ".cache"))).To(BeFalse())
+			})
+		})
+	})
+})