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package libpod
import (
"fmt"
"io/ioutil"
"os"
"strings"
"sync"
"time"
"github.com/hpcloud/tail"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
const (
// logTimeFormat is the time format used in the log.
// It is a modified version of RFC3339Nano that guarantees trailing
// zeroes are not trimmed, taken from
// https://github.com/golang/go/issues/19635
logTimeFormat = "2006-01-02T15:04:05.000000000Z07:00"
// partialLogType signifies a log line that exceeded the buffer
// length and needed to spill into a new line
partialLogType = "P"
// fullLogType signifies a log line is full
fullLogType = "F"
)
// LogOptions is the options you can use for logs
type LogOptions struct {
Details bool
Follow bool
Since time.Time
Tail uint64
Timestamps bool
Multi bool
WaitGroup *sync.WaitGroup
}
// LogLine describes the information for each line of a log
type LogLine struct {
Device string
ParseLogType string
Time time.Time
Msg string
CID string
}
// Log is a runtime function that can read one or more container logs.
func (r *Runtime) Log(containers []*Container, options *LogOptions, logChannel chan *LogLine) error {
for _, ctr := range containers {
if err := ctr.ReadLog(options, logChannel); err != nil {
return err
}
}
return nil
}
// ReadLog reads a containers log based on the input options and returns loglines over a channel
func (c *Container) ReadLog(options *LogOptions, logChannel chan *LogLine) error {
// TODO Skip sending logs until journald logs can be read
// TODO make this not a magic string
if c.LogDriver() == JournaldLogging {
return c.readFromJournal(options, logChannel)
}
return c.readFromLogFile(options, logChannel)
}
func (c *Container) readFromLogFile(options *LogOptions, logChannel chan *LogLine) error {
t, tailLog, err := getLogFile(c.LogPath(), options)
if err != nil {
// If the log file does not exist, this is not fatal.
if os.IsNotExist(errors.Cause(err)) {
return nil
}
return errors.Wrapf(err, "unable to read log file %s for %s ", c.ID(), c.LogPath())
}
options.WaitGroup.Add(1)
if len(tailLog) > 0 {
for _, nll := range tailLog {
nll.CID = c.ID()
if nll.Since(options.Since) {
logChannel <- nll
}
}
}
go func() {
var partial string
for line := range t.Lines {
nll, err := newLogLine(line.Text)
if err != nil {
logrus.Error(err)
continue
}
if nll.Partial() {
partial = partial + nll.Msg
continue
} else if !nll.Partial() && len(partial) > 1 {
nll.Msg = partial
partial = ""
}
nll.CID = c.ID()
if nll.Since(options.Since) {
logChannel <- nll
}
}
options.WaitGroup.Done()
}()
return nil
}
// getLogFile returns an hp tail for a container given options
func getLogFile(path string, options *LogOptions) (*tail.Tail, []*LogLine, error) {
var (
whence int
err error
logTail []*LogLine
)
// whence 0=origin, 2=end
if options.Tail > 0 {
whence = 2
logTail, err = getTailLog(path, int(options.Tail))
if err != nil {
return nil, nil, err
}
}
seek := tail.SeekInfo{
Offset: 0,
Whence: whence,
}
t, err := tail.TailFile(path, tail.Config{MustExist: true, Poll: true, Follow: options.Follow, Location: &seek, Logger: tail.DiscardingLogger})
return t, logTail, err
}
func getTailLog(path string, tail int) ([]*LogLine, error) {
var (
tailLog []*LogLine
nlls []*LogLine
tailCounter int
partial string
)
content, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
splitContent := strings.Split(string(content), "\n")
// We read the content in reverse and add each nll until we have the same
// number of F type messages as the desired tail
for i := len(splitContent) - 1; i >= 0; i-- {
if len(splitContent[i]) == 0 {
continue
}
nll, err := newLogLine(splitContent[i])
if err != nil {
return nil, err
}
nlls = append(nlls, nll)
if !nll.Partial() {
tailCounter = tailCounter + 1
}
if tailCounter == tail {
break
}
}
// Now we iterate the results and assemble partial messages to become full messages
for _, nll := range nlls {
if nll.Partial() {
partial = partial + nll.Msg
} else {
nll.Msg = nll.Msg + partial
tailLog = append(tailLog, nll)
partial = ""
}
}
return tailLog, nil
}
// String converts a logline to a string for output given whether a detail
// bool is specified.
func (l *LogLine) String(options *LogOptions) string {
var out string
if options.Multi {
cid := l.CID
if len(cid) > 12 {
cid = cid[:12]
}
out = fmt.Sprintf("%s ", cid)
}
if options.Timestamps {
out = out + fmt.Sprintf("%s ", l.Time.Format(logTimeFormat))
}
return out + l.Msg
}
// Since returns a bool as to whether a log line occurred after a given time
func (l *LogLine) Since(since time.Time) bool {
return l.Time.After(since)
}
// newLogLine creates a logLine struct from a container log string
func newLogLine(line string) (*LogLine, error) {
splitLine := strings.Split(line, " ")
if len(splitLine) < 4 {
return nil, errors.Errorf("'%s' is not a valid container log line", line)
}
logTime, err := time.Parse(logTimeFormat, splitLine[0])
if err != nil {
return nil, errors.Wrapf(err, "unable to convert time %s from container log", splitLine[0])
}
l := LogLine{
Time: logTime,
Device: splitLine[1],
ParseLogType: splitLine[2],
Msg: strings.Join(splitLine[3:], " "),
}
return &l, nil
}
// Partial returns a bool if the log line is a partial log type
func (l *LogLine) Partial() bool {
if l.ParseLogType == partialLogType {
return true
}
return false
}
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