Unpack tar from GCS bucket

pkg/constants/constants.go

@@ -26,7 +26,17 @@ const (
 	// WorkspaceDir is the path to the workspace directory
 	WorkspaceDir = "/workspace"
 
+	//KbuildDir is the path to the kbuild directory
+	KbuildDir = "/kbuild"
+
 	WhitelistPath = "/proc/self/mountinfo"
 
 	Author = "kbuild"
+
+	// KbuildTar is the default name of the tar uploaded to GCS buckets
+	KbuildTar = "kbuild.tar"
+
+	// BuildContextDir is the directory a build context will be unpacked into,
+	// for example, a tarball from a GCS bucket will be unpacked here
+	BuildContextDir = "/kbuild/buildcontext/"
 )

pkg/util/bucket_util.go

@@ -0,0 +1,73 @@
+/*
+Copyright 2018 Google LLC
+
+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 util
+
+import (
+	"cloud.google.com/go/storage"
+	pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
+	"github.com/GoogleCloudPlatform/k8s-container-builder/pkg/constants"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/net/context"
+	"os"
+	"path/filepath"
+)
+
+// UnpackTarFromGCSBucket unpacks the kbuild.tar file in the given bucket to the given directory
+func UnpackTarFromGCSBucket(bucketName, directory string) error {
+	// Get the tar from the bucket
+	tarPath, err := getTarFromBucket(bucketName, directory)
+	if err != nil {
+		return err
+	}
+	logrus.Debug("Unpacking source context tar...")
+	// Now, unpack the tar to a build context, and return the path to the build context
+	file, err := os.Open(tarPath)
+	if err != nil {
+		return err
+	}
+	if err := pkgutil.UnTar(file, directory, nil); err != nil {
+		return err
+	}
+	// Remove the tar so it doesn't interfere with subsequent commands
+	logrus.Debugf("Deleting %s", tarPath)
+	return os.Remove(tarPath)
+}
+
+// getTarFromBucket gets kbuild.tar from the GCS bucket and saves it to the filesystem
+// It returns the path to the tar file
+func getTarFromBucket(bucketName, directory string) (string, error) {
+	ctx := context.Background()
+	client, err := storage.NewClient(ctx)
+	if err != nil {
+		return "", err
+	}
+	bucket := client.Bucket(bucketName)
+
+	// Get the tarfile kbuild.tar from the GCS bucket, and save it to a tar object
+
+	reader, err := bucket.Object(constants.KbuildTar).NewReader(ctx)
+	if err != nil {
+		return "", err
+	}
+	defer reader.Close()
+	tarPath := filepath.Join(directory, constants.KbuildTar)
+	if err := CreateFile(tarPath, reader, 0600); err != nil {
+		return "", err
+	}
+	logrus.Debugf("Copied tarball %s from GCS bucket %s to %s", constants.KbuildTar, bucketName, tarPath)
+	return tarPath, nil
+}