README
¶
file-rotatelogs
Provide an io.Writer that periodically rotates log files from within the application. Port of File::RotateLogs from Perl to Go.
SYNOPSIS
import (
"log"
"net/http"
apachelog "github.com/lestrrat-go/apache-logformat"
rotatelogs "github.com/lestrrat-go/file-rotatelogs"
)
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { ... })
logf, err := rotatelogs.New(
"/path/to/access_log.%Y%m%d%H%M",
rotatelogs.WithLinkName("/path/to/access_log"),
rotatelogs.WithMaxAge(24 * time.Hour),
rotatelogs.WithRotationTime(time.Hour),
)
if err != nil {
log.Printf("failed to create rotatelogs: %s", err)
return
}
// Now you must write to logf. apache-logformat library can create
// a http.Handler that only writes the approriate logs for the request
// to the given handle
http.ListenAndServe(":8080", apachelog.CombinedLog.Wrap(mux, logf))
}
DESCRIPTION
When you integrate this to into your app, it automatically write to logs that are rotated from within the app: No more disk-full alerts because you forgot to setup logrotate!
To install, simply issue a go get:
go get github.com/lestrrat-go/file-rotatelogs
It's normally expected that this library is used with some other
logging service, such as the built-in log library, or loggers
such as github.com/lestrrat-go/apache-logformat.
import(
"log"
"github.com/lestrrat-go/file-rotatelogs"
)
func main() {
rl, _ := rotatelogs.New("/path/to/access_log.%Y%m%d%H%M")
log.SetOutput(rl)
/* elsewhere ... */
log.Printf("Hello, World!")
}
OPTIONS
Pattern (Required)
The pattern used to generate actual log file names. You should use patterns using the strftime (3) format. For example:
rotatelogs.New("/var/log/myapp/log.%Y%m%d")
Clock (default: rotatelogs.Local)
You may specify an object that implements the roatatelogs.Clock interface. When this option is supplied, it's used to determine the current time to base all of the calculations on. For example, if you want to base your calculations in UTC, you may specify rotatelogs.UTC
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithClock(rotatelogs.UTC),
)
Location
This is an alternative to the WithClock option. Instead of providing an
explicit clock, you can provide a location for you times. We will create
a Clock object that produces times in your specified location, and configure
the rotatelog to respect it.
LinkName (default: "")
Path where a symlink for the actual log file is placed. This allows you to always check at the same location for log files even if the logs were rotated
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithLinkName("/var/log/myapp/current"),
)
// Else where
$ tail -f /var/log/myapp/current
Links that share the same parent directory with the main log path will get a special treatment: namely, linked paths will be RELATIVE to the main log file.
| Main log file name | Link name | Linked path |
|---|---|---|
| /path/to/log.%Y%m%d | /path/to/log | log.YYYYMMDD |
| /path/to/log.%Y%m%d | /path/to/nested/log | ../log.YYYYMMDD |
| /path/to/log.%Y%m%d | /foo/bar/baz/log | /path/to/log.YYYYMMDD |
If not provided, no link will be written.
RotationTime (default: 86400 sec)
Interval between file rotation. By default logs are rotated every 86400 seconds. Note: Remember to use time.Duration values.
// Rotate every hour
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithRotationTime(time.Hour),
)
MaxAge (default: 7 days)
Time to wait until old logs are purged. By default no logs are purged, which certainly isn't what you want. Note: Remember to use time.Duration values.
// Purge logs older than 1 hour
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithMaxAge(time.Hour),
)
RotationCount (default: -1)
The number of files should be kept. By default, this option is disabled.
Note: MaxAge should be disabled by specifing WithMaxAge(-1) explicitly.
// Purge logs except latest 7 files
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithMaxAge(-1),
rotatelogs.WithRotationCount(7),
)
Handler (default: nil)
Sets the event handler to receive event notifications from the RotateLogs object. Currently only supported event type is FiledRotated
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.Handler(rotatelogs.HandlerFunc(func(e Event) {
if e.Type() != rotatelogs.FileRotatedEventType {
return
}
// Do what you want with the data. This is just an idea:
storeLogFileToRemoteStorage(e.(*FileRotatedEvent).PreviousFile())
})),
)
ForceNewFile
Ensure a new file is created every time New() is called. If the base file name already exists, an implicit rotation is performed.
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.ForceNewFile(),
)
Rotating files forcefully
If you want to rotate files forcefully before the actual rotation time has reached,
you may use the Rotate() method. This method forcefully rotates the logs, but
if the generated file name clashes, then a numeric suffix is added so that
the new file will forcefully appear on disk.
For example, suppose you had a pattern of '%Y.log' with a rotation time of
86400 so that it only gets rotated every year, but for whatever reason you
wanted to rotate the logs now, you could install a signal handler to
trigger this rotation:
rl := rotatelogs.New(...)
signal.Notify(ch, syscall.SIGHUP)
go func(ch chan os.Signal) {
<-ch
rl.Rotate()
}()
And you will get a log file name in like 2018.log.1, 2018.log.2, etc.
Documentation
¶
Overview ¶
package rotatelogs is a port of File-RotateLogs from Perl (https://metacpan.org/release/File-RotateLogs), and it allows you to automatically rotate output files when you write to them according to the filename pattern that you can specify.
Index ¶
- Variables
- type Clock
- type Event
- type EventType
- type FileRotatedEvent
- type Handler
- type HandlerFunc
- type Option
- func ForceNewFile() Option
- func WithClock(c Clock) Option
- func WithHandler(h Handler) Option
- func WithLinkName(s string) Option
- func WithLocation(loc *time.Location) Option
- func WithMaxAge(d time.Duration) Option
- func WithRotationCount(n uint) Option
- func WithRotationSize(s int64) Option
- func WithRotationTime(d time.Duration) Option
- type RotateLogs
Constants ¶
This section is empty.
Variables ¶
var Local = clockFn(time.Now)
Local is an object satisfying the Clock interface, which returns the current time in the local timezone
var UTC = clockFn(func() time.Time { return time.Now().UTC() })
UTC is an object satisfying the Clock interface, which returns the current time in UTC
Functions ¶
This section is empty.
Types ¶
type FileRotatedEvent ¶
type FileRotatedEvent struct {
// contains filtered or unexported fields
}
func (*FileRotatedEvent) CurrentFile ¶
func (e *FileRotatedEvent) CurrentFile() string
func (*FileRotatedEvent) PreviousFile ¶
func (e *FileRotatedEvent) PreviousFile() string
func (*FileRotatedEvent) Type ¶
func (e *FileRotatedEvent) Type() EventType
type HandlerFunc ¶
type HandlerFunc func(Event)
func (HandlerFunc) Handle ¶
func (h HandlerFunc) Handle(e Event)
type Option ¶
type Option interface {
Name() string
Value() interface{}
}
Option is used to pass optional arguments to the RotateLogs constructor
func ForceNewFile ¶
func ForceNewFile() Option
ForceNewFile ensures a new file is created every time New() is called. If the base file name already exists, an implicit rotation is performed
func WithClock ¶
WithClock creates a new Option that sets a clock that the RotateLogs object will use to determine the current time.
By default rotatelogs.Local, which returns the current time in the local time zone, is used. If you would rather use UTC, use rotatelogs.UTC as the argument to this option, and pass it to the constructor.
func WithHandler ¶
WithHandler creates a new Option that specifies the Handler object that gets invoked when an event occurs. Currently `FileRotated` event is supported
func WithLinkName ¶
WithLinkName creates a new Option that sets the symbolic link name that gets linked to the current file name being used.
func WithLocation ¶
WithLocation creates a new Option that sets up a "Clock" interface that the RotateLogs object will use to determine the current time.
This optin works by always returning the in the given location.
func WithMaxAge ¶
WithMaxAge creates a new Option that sets the max age of a log file before it gets purged from the file system.
func WithRotationCount ¶
WithRotationCount creates a new Option that sets the number of files should be kept before it gets purged from the file system.
func WithRotationSize ¶
WithRotationSize creates a new Option that sets the log file size between rotation.
func WithRotationTime ¶
WithRotationTime creates a new Option that sets the time between rotation.
type RotateLogs ¶
type RotateLogs struct {
// contains filtered or unexported fields
}
RotateLogs represents a log file that gets automatically rotated as you write to it.
func New ¶
func New(p string, options ...Option) (*RotateLogs, error)
New creates a new RotateLogs object. A log filename pattern must be passed. Optional `Option` parameters may be passed
func (*RotateLogs) Close ¶
func (rl *RotateLogs) Close() error
Close satisfies the io.Closer interface. You must call this method if you performed any writes to the object.
func (*RotateLogs) CurrentFileName ¶
func (rl *RotateLogs) CurrentFileName() string
CurrentFileName returns the current file name that the RotateLogs object is writing to
func (*RotateLogs) Rotate ¶
func (rl *RotateLogs) Rotate() error
Rotate forcefully rotates the log files. If the generated file name clash because file already exists, a numeric suffix of the form ".1", ".2", ".3" and so forth are appended to the end of the log file
Thie method can be used in conjunction with a signal handler so to emulate servers that generate new log files when they receive a SIGHUP
func (*RotateLogs) Write ¶
func (rl *RotateLogs) Write(p []byte) (n int, err error)
Write satisfies the io.Writer interface. It writes to the appropriate file handle that is currently being used. If we have reached rotation time, the target file gets automatically rotated, and also purged if necessary.
Source Files
Directories