99 lines
2.4 KiB
Go
99 lines
2.4 KiB
Go
/*
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Copyright 2018 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package snapshot
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import (
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"archive/tar"
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"bytes"
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"github.com/GoogleCloudPlatform/k8s-container-builder/pkg/util"
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"github.com/sirupsen/logrus"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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)
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// Snapshotter holds the root directory from which to take snapshots, and a list of snapshots taken
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type Snapshotter struct {
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l *LayeredMap
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directory string
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snapshots []string
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}
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// NewSnapshotter creates a new snapshotter rooted at d
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func NewSnapshotter(l *LayeredMap, d string) *Snapshotter {
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return &Snapshotter{l: l, directory: d, snapshots: []string{}}
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}
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// Init initializes a new snapshotter
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func (s *Snapshotter) Init() error {
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if _, err := s.snapShotFS(ioutil.Discard); err != nil {
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return err
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}
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return nil
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}
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// TakeSnapshot takes a snapshot of the filesystem, avoiding directories in the whitelist
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// It stores changed files in a tar, and returns the contents of this tar at the end
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func (s *Snapshotter) TakeSnapshot() ([]byte, error) {
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buf := bytes.NewBuffer([]byte{})
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added, err := s.snapShotFS(buf)
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if err != nil {
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return nil, err
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}
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if !added {
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logrus.Infof("No files were changed in this command, this layer will not be appended.")
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return nil, nil
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}
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if err != nil {
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return nil, err
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}
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// Add buffer contents until buffer is empty
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var contents []byte
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for {
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next := buf.Next(buf.Len())
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if len(next) == 0 {
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break
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}
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contents = append(contents, next...)
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}
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return contents, nil
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}
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func (s *Snapshotter) snapShotFS(f io.Writer) (bool, error) {
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s.l.Snapshot()
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added := false
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w := tar.NewWriter(f)
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defer w.Close()
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err := filepath.Walk(s.directory, func(path string, info os.FileInfo, err error) error {
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if util.PathInWhitelist(path, s.directory) {
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return nil
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}
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// Only add to the tar if we add it to the layeredmap.
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if s.l.MaybeAdd(path) {
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added = true
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return util.AddToTar(path, info, w)
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}
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return nil
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})
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return added, err
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}
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