agent: Introduce File Logger

This commit introduces a rotating file logger for Nomad Agent Logs. The
logger implementation itself is a lift and shift from Consul, with tests
updated to fit with the Nomad pattern of using require, and not having a
testutil for creating tempdirs cleanly.
This commit is contained in:
Danielle Lancashire
2019-10-07 14:37:31 +02:00
parent 234d113a81
commit fff69a50e3
2 changed files with 309 additions and 0 deletions

138
command/agent/log_file.go Normal file
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package agent
import (
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"time"
"github.com/hashicorp/logutils"
)
var (
now = time.Now
)
// logFile is used to setup a file based logger that also performs log rotation
type logFile struct {
// Log level Filter to filter out logs that do not matcch LogLevel criteria
logFilter *logutils.LevelFilter
//Name of the log file
fileName string
//Path to the log file
logPath string
//Duration between each file rotation operation
duration time.Duration
//LastCreated represents the creation time of the latest log
LastCreated time.Time
//FileInfo is the pointer to the current file being written to
FileInfo *os.File
//MaxBytes is the maximum number of desired bytes for a log file
MaxBytes int
//BytesWritten is the number of bytes written in the current log file
BytesWritten int64
// Max rotated files to keep before removing them.
MaxFiles int
//acquire is the mutex utilized to ensure we have no concurrency issues
acquire sync.Mutex
}
func (l *logFile) fileNamePattern() string {
// Extract the file extension
fileExt := filepath.Ext(l.fileName)
// If we have no file extension we append .log
if fileExt == "" {
fileExt = ".log"
}
// Remove the file extension from the filename
return strings.TrimSuffix(l.fileName, fileExt) + "-%s" + fileExt
}
func (l *logFile) openNew() error {
fileNamePattern := l.fileNamePattern()
// New file name has the format : filename-timestamp.extension
createTime := now()
newfileName := fmt.Sprintf(fileNamePattern, strconv.FormatInt(createTime.UnixNano(), 10))
newfilePath := filepath.Join(l.logPath, newfileName)
// Try creating a file. We truncate the file because we are the only authority to write the logs
filePointer, err := os.OpenFile(newfilePath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0640)
if err != nil {
return err
}
l.FileInfo = filePointer
// New file, new bytes tracker, new creation time :)
l.LastCreated = createTime
l.BytesWritten = 0
return nil
}
func (l *logFile) rotate() error {
// Get the time from the last point of contact
timeElapsed := time.Since(l.LastCreated)
// Rotate if we hit the byte file limit or the time limit
if (l.BytesWritten >= int64(l.MaxBytes) && (l.MaxBytes > 0)) || timeElapsed >= l.duration {
l.FileInfo.Close()
if err := l.pruneFiles(); err != nil {
return err
}
return l.openNew()
}
return nil
}
func (l *logFile) pruneFiles() error {
if l.MaxFiles == 0 {
return nil
}
pattern := l.fileNamePattern()
//get all the files that match the log file pattern
globExpression := filepath.Join(l.logPath, fmt.Sprintf(pattern, "*"))
matches, err := filepath.Glob(globExpression)
if err != nil {
return err
}
// Prune if there are more files stored than the configured max
stale := len(matches) - l.MaxFiles
for i := 0; i < stale; i++ {
if err := os.Remove(matches[i]); err != nil {
return err
}
}
return nil
}
// Write is used to implement io.Writer
func (l *logFile) Write(b []byte) (n int, err error) {
// Filter out log entries that do not match log level criteria
if !l.logFilter.Check(b) {
return 0, nil
}
l.acquire.Lock()
defer l.acquire.Unlock()
//Create a new file if we have no file to write to
if l.FileInfo == nil {
if err := l.openNew(); err != nil {
return 0, err
}
}
// Check for the last contact and rotate if necessary
if err := l.rotate(); err != nil {
return 0, err
}
l.BytesWritten += int64(len(b))
return l.FileInfo.Write(b)
}

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package agent
import (
"io/ioutil"
"os"
"path/filepath"
"testing"
"time"
"github.com/hashicorp/logutils"
"github.com/stretchr/testify/require"
)
const (
testFileName = "Nomad.log"
testDuration = 2 * time.Second
testBytes = 10
)
func TestLogFile_timeRotation(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterTimeTest")
require.NoError(err)
defer os.Remove(tempDir)
filt := LevelFilter()
logFile := logFile{
logFilter: filt,
fileName: testFileName,
logPath: tempDir,
duration: testDuration,
}
logFile.Write([]byte("Hello World"))
time.Sleep(2 * time.Second)
logFile.Write([]byte("Second File"))
want := 2
if got, _ := ioutil.ReadDir(tempDir); len(got) != want {
t.Errorf("Expected %d files, got %v file(s)", want, len(got))
}
}
func TestLogFile_openNew(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterOpenTest")
require.NoError(err)
defer os.Remove(tempDir)
logFile := logFile{fileName: testFileName, logPath: tempDir, duration: testDuration}
require.NoError(logFile.openNew())
_, err = ioutil.ReadFile(logFile.FileInfo.Name())
require.NoError(err)
}
func TestLogFile_byteRotation(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterByteTest")
require.NoError(err)
defer os.Remove(tempDir)
filt := LevelFilter()
filt.MinLevel = logutils.LogLevel("INFO")
logFile := logFile{
logFilter: filt,
fileName: testFileName,
logPath: tempDir,
MaxBytes: testBytes,
duration: 24 * time.Hour,
}
logFile.Write([]byte("Hello World"))
logFile.Write([]byte("Second File"))
want := 2
tempFiles, _ := ioutil.ReadDir(tempDir)
require.Equal(want, len(tempFiles))
}
func TestLogFile_logLevelFiltering(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterFilterTest")
require.NoError(err)
defer os.Remove(tempDir)
filt := LevelFilter()
logFile := logFile{
logFilter: filt,
fileName: testFileName,
logPath: tempDir,
MaxBytes: testBytes,
duration: testDuration,
}
logFile.Write([]byte("[INFO] This is an info message"))
logFile.Write([]byte("[DEBUG] This is a debug message"))
logFile.Write([]byte("[ERR] This is an error message"))
want := 2
tempFiles, _ := ioutil.ReadDir(tempDir)
require.Equal(want, len(tempFiles))
}
func TestLogFile_deleteArchives(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterDeleteArchivesTest")
require.NoError(err)
defer os.Remove(tempDir)
filt := LevelFilter()
filt.MinLevel = logutils.LogLevel("INFO")
logFile := logFile{
logFilter: filt,
fileName: testFileName,
logPath: tempDir,
MaxBytes: testBytes,
duration: 24 * time.Hour,
MaxFiles: 1,
}
logFile.Write([]byte("[INFO] Hello World"))
logFile.Write([]byte("[INFO] Second File"))
logFile.Write([]byte("[INFO] Third File"))
want := 2
tempFiles, _ := ioutil.ReadDir(tempDir)
require.Equal(want, len(tempFiles))
for _, tempFile := range tempFiles {
var bytes []byte
var err error
path := filepath.Join(tempDir, tempFile.Name())
if bytes, err = ioutil.ReadFile(path); err != nil {
t.Errorf(err.Error())
return
}
contents := string(bytes)
require.NotEqual("[INFO] Hellow World", contents, "oldest log should have been deleted")
}
}
func TestLogFile_deleteArchivesDisabled(t *testing.T) {
t.Parallel()
require := require.New(t)
tempDir, err := ioutil.TempDir("", "LogWriterDeleteArchivesDisabledTest")
require.NoError(err)
defer os.Remove(tempDir)
filt := LevelFilter()
filt.MinLevel = logutils.LogLevel("INFO")
logFile := logFile{
logFilter: filt,
fileName: testFileName,
logPath: tempDir,
MaxBytes: testBytes,
duration: 24 * time.Hour,
MaxFiles: 0,
}
logFile.Write([]byte("[INFO] Hello World"))
logFile.Write([]byte("[INFO] Second File"))
logFile.Write([]byte("[INFO] Third File"))
want := 3
tempFiles, _ := ioutil.ReadDir(tempDir)
require.Equal(want, len(tempFiles))
}