github.com/coreos/mantle@v0.13.0/network/journal/record.go (about)

     1  // Copyright 2017 CoreOS, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package journal
    16  
    17  import (
    18  	"context"
    19  	"io"
    20  	"os"
    21  
    22  	"github.com/kballard/go-shellquote"
    23  	"golang.org/x/crypto/ssh"
    24  
    25  	"github.com/coreos/mantle/system/exec"
    26  )
    27  
    28  type Recorder struct {
    29  	formatter Formatter
    30  	cursor    string
    31  	status    chan error
    32  	rawFile   io.WriteCloser
    33  }
    34  
    35  func NewRecorder(f Formatter, rawFile io.WriteCloser) *Recorder {
    36  	return &Recorder{
    37  		formatter: f,
    38  		rawFile:   rawFile,
    39  		status:    make(chan error, 1),
    40  	}
    41  }
    42  
    43  func (r *Recorder) journalctl() []string {
    44  	cmd := []string{"journalctl",
    45  		"--output=export", "--follow", "--lines=all"}
    46  	if r.cursor == "" {
    47  		cmd = append(cmd, "--boot")
    48  	} else {
    49  		cmd = append(cmd, "--after-cursor", r.cursor)
    50  	}
    51  	return cmd
    52  }
    53  
    54  func (r *Recorder) record(export io.Reader) error {
    55  	exportTee := io.TeeReader(export, r.rawFile)
    56  	src := NewExportReader(exportTee)
    57  	for {
    58  		entry, err := src.ReadEntry()
    59  		if err != nil {
    60  			if err == io.EOF {
    61  				err = nil
    62  			}
    63  			return err
    64  		}
    65  
    66  		r.cursor = string(entry[FIELD_CURSOR])
    67  
    68  		if err := r.formatter.WriteEntry(entry); err != nil {
    69  			return err
    70  		}
    71  	}
    72  }
    73  
    74  func (r *Recorder) StartSSH(ctx context.Context, client *ssh.Client) error {
    75  	ctx, cancel := context.WithCancel(ctx)
    76  	go func() {
    77  		<-ctx.Done()
    78  		client.Close()
    79  	}()
    80  
    81  	journal, err := client.NewSession()
    82  	if err != nil {
    83  		cancel()
    84  		return err
    85  	}
    86  	journal.Stderr = os.Stderr
    87  
    88  	export, err := journal.StdoutPipe()
    89  	if err != nil {
    90  		cancel()
    91  		return err
    92  	}
    93  
    94  	cmd := shellquote.Join(r.journalctl()...)
    95  	if err := journal.Start(cmd); err != nil {
    96  		cancel()
    97  		return err
    98  	}
    99  
   100  	go func() {
   101  		err := r.record(export)
   102  		cancel()
   103  		err2 := journal.Wait()
   104  		// Tolerate closed/canceled SSH connections.
   105  		if _, ok := err2.(*ssh.ExitMissingError); ok {
   106  			err2 = nil
   107  		}
   108  		if err == nil && err2 != nil {
   109  			err = err2
   110  		}
   111  		r.status <- err
   112  	}()
   113  
   114  	return nil
   115  }
   116  
   117  func (r *Recorder) StartLocal(ctx context.Context) error {
   118  	cmd := r.journalctl()
   119  	journal := exec.CommandContext(ctx, cmd[0], cmd[1:]...)
   120  	journal.Stderr = os.Stderr
   121  
   122  	export, err := journal.StdoutPipe()
   123  	if err != nil {
   124  		return err
   125  	}
   126  
   127  	if err := journal.Start(); err != nil {
   128  		return err
   129  	}
   130  
   131  	go func() {
   132  		err := r.record(export)
   133  		err2 := journal.Wait()
   134  		if err == nil && err2 != nil {
   135  			err = err2
   136  		}
   137  		r.status <- err
   138  	}()
   139  
   140  	return nil
   141  }
   142  
   143  func (r *Recorder) Wait() error {
   144  	return <-r.status
   145  }
   146  
   147  func (r *Recorder) RunSSH(ctx context.Context, client *ssh.Client) error {
   148  	if err := r.StartSSH(ctx, client); err != nil {
   149  		return err
   150  	}
   151  	return r.Wait()
   152  }
   153  
   154  func (r *Recorder) RunLocal(ctx context.Context) error {
   155  	if err := r.StartLocal(ctx); err != nil {
   156  		return err
   157  	}
   158  	return r.Wait()
   159  }