mirror of
https://github.com/vmware-tanzu/velero.git
synced 2026-01-06 13:26:26 +00:00
114 lines
2.6 KiB
Go
114 lines
2.6 KiB
Go
/*
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Copyright The Velero Contributors.
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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 logging
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import (
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"bytes"
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"io"
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"os"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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)
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const (
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ListeningLevel = logrus.ErrorLevel
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ListeningMessage = "merge-log-57847fd0-0c7c-48e3-b5f7-984b293d8376"
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LogSourceKey = "log-source"
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)
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// MergeHook is used to redirect a batch of logs to another logger atomically.
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// It hooks a log with ListeningMessage message, once the message is hit it replaces
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// the logger's output to HookWriter so that HookWriter retrieves the logs from a file indicated
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// by LogSourceKey field.
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type MergeHook struct {
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}
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type hookWriter struct {
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orgWriter io.Writer
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source string
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logger *logrus.Logger
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}
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func newHookWriter(orgWriter io.Writer, source string, logger *logrus.Logger) io.Writer {
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return &hookWriter{
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orgWriter: orgWriter,
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source: source,
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logger: logger,
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}
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}
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func (h *MergeHook) Levels() []logrus.Level {
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return []logrus.Level{ListeningLevel}
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}
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func (h *MergeHook) Fire(entry *logrus.Entry) error {
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if entry.Message != ListeningMessage {
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return nil
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}
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source, exist := entry.Data[LogSourceKey]
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if !exist {
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return nil
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}
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entry.Logger.SetOutput(newHookWriter(entry.Logger.Out, source.(string), entry.Logger))
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return nil
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}
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func (w *hookWriter) Write(p []byte) (n int, err error) {
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if !bytes.Contains(p, []byte(ListeningMessage)) {
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return w.orgWriter.Write(p)
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}
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defer func() {
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w.logger.Out = w.orgWriter
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}()
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sourceFile, err := os.OpenFile(w.source, os.O_RDONLY, 0400)
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if err != nil {
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return 0, err
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}
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defer sourceFile.Close()
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total := 0
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buffer := make([]byte, 2048)
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for {
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read, err := sourceFile.Read(buffer)
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if err == io.EOF {
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return total, nil
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}
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if err != nil {
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return total, errors.Wrapf(err, "error to read source file %s at pos %v", w.source, total)
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}
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written, err := w.orgWriter.Write(buffer[0:read])
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if err != nil {
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return total, errors.Wrapf(err, "error to write log at pos %v", total)
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}
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if written != read {
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return total, errors.Errorf("error to write log at pos %v, read %v but written %v", total, read, written)
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}
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total += read
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}
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}
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