Merge pull request #382 from developer-guy/feature/diff

oci/client: add diff capability

oci/client/diff.go

@@ -0,0 +1,92 @@
+/*
+Copyright 2022 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package client
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/google/go-containerregistry/pkg/crane"
+	"github.com/google/go-containerregistry/pkg/name"
+)
+
+// Diff compares the files included in an OCI image with the local files in the given path
+// and returns an error if the contents is different
+func (c *Client) Diff(ctx context.Context, url, dir string, ignorePaths []string) error {
+	_, err := name.ParseReference(url)
+	if err != nil {
+		return fmt.Errorf("invalid URL: %w", err)
+	}
+
+	tmpBuildDir, err := os.MkdirTemp("", "ocibuild")
+	if err != nil {
+		return fmt.Errorf("creating temp build dir failed: %w", err)
+	}
+	defer os.RemoveAll(tmpBuildDir)
+
+	tmpFile := filepath.Join(tmpBuildDir, "artifact.tgz")
+
+	if err := c.Build(tmpFile, dir, ignorePaths); err != nil {
+		return fmt.Errorf("building artifact failed: %w", err)
+	}
+
+	f, err := os.Open(tmpFile)
+	if err != nil {
+		return fmt.Errorf("opening artifact failed: %w", err)
+	}
+	defer f.Close()
+
+	h1 := sha256.New()
+	if _, err := io.Copy(h1, f); err != nil {
+		return fmt.Errorf("calculating artifact hash failed: %w", err)
+	}
+
+	img, err := crane.Pull(url, c.optionsWithContext(ctx)...)
+	if err != nil {
+		return err
+	}
+
+	layers, err := img.Layers()
+	if err != nil {
+		return fmt.Errorf("failed to list layers: %w", err)
+	}
+
+	if len(layers) < 1 {
+		return fmt.Errorf("no layers found in artifact")
+	}
+
+	blob, err := layers[0].Compressed()
+	if err != nil {
+		return fmt.Errorf("extracting first layer failed: %w", err)
+	}
+
+	h2 := sha256.New()
+	if _, err := io.Copy(h2, blob); err != nil {
+		return fmt.Errorf("calculating hash failed: %w", err)
+	}
+
+	if bytes.Compare(h1.Sum(nil), h2.Sum(nil)) != 0 {
+		return fmt.Errorf("the remote artifact contents differs from the local one")
+	}
+
+	return nil
+}

oci/client/diff_test.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2022 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package client
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	_ "github.com/google/go-containerregistry/pkg/crane"
+	. "github.com/onsi/gomega"
+)
+
+func TestClient_Diff(t *testing.T) {
+	g := NewWithT(t)
+	ctx := context.Background()
+	c := NewLocalClient()
+	tag := "v0.0.1"
+	repo := "test-push" + randStringRunes(5)
+
+	url := fmt.Sprintf("%s/%s:%s", dockerReg, repo, tag)
+	metadata := Metadata{
+		Source:   "github.com/fluxcd/flux2",
+		Revision: "rev",
+	}
+
+	testDir := "testdata/artifact"
+	_, err := c.Push(ctx, url, testDir, metadata, nil)
+	g.Expect(err).ToNot(HaveOccurred())
+
+	err = c.Diff(ctx, url, testDir, nil)
+	g.Expect(err).ToNot(HaveOccurred())
+
+	tmpBuildDir, err := os.MkdirTemp("", "oci")
+	g.Expect(err).ToNot(HaveOccurred())
+	defer os.RemoveAll(tmpBuildDir)
+
+	g.Expect(os.WriteFile(filepath.Join(tmpBuildDir, "test.txt"), []byte("test"), 0600)).ToNot(HaveOccurred())
+
+	newTag := "v0.0.2"
+	url = fmt.Sprintf("%s/%s:%s", dockerReg, repo, newTag)
+
+	_, err = c.Push(ctx, url, tmpBuildDir, metadata, nil)
+	g.Expect(err).ToNot(HaveOccurred())
+
+	err = c.Diff(ctx, url, testDir, nil)
+	g.Expect(err).To(HaveOccurred())
+}