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accesslog.go
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accesslog.go
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// Copyright 2016 Granitic. All rights reserved.
// Use of this source code is governed by an Apache 2.0 license that can be found in the LICENSE file at the root of this project.
package httpserver
import (
"bytes"
"context"
"errors"
"fmt"
"github.com/graniticio/granitic/httpendpoint"
"github.com/graniticio/granitic/ioc"
"net/http"
"os"
"regexp"
"strconv"
"strings"
"time"
)
const percent = "%"
const hyphen = "-"
const unsupportedPlaceholder = "???"
const presetCommonName = "common"
const presetCommonFormat = "%h %l %u %t \"%r\" %s %b"
const presetCombinedName = "combined"
// The log format used when AccessLogWriter.LogLinePreset is set to combined. Similar to the Apache HTTP preset of the same name.
const PresetCombinedFormat = "%h %l %u %t \"%r\" %s %b \"%{Referer}i\" \"%{User-agent}i\""
const presetframeworkName = "framework"
// The log format used when AccessLogWriter.LogLinePreset is set to framework. Uses the X-Forwarded-For header to show all
// IP addresses that the request has been proxied for (useful for services that sit behind multiple load-balancers and proxies) and logs
// processing time in microseconds.
const PresetFrameworkFormat = "%h XFF[%{X-Forwarded-For}i] %l %u [%{02/Jan/2006:15:04:05 Z0700}t] \"%m %U%q\" %s %bB %{us}Tμs"
const formatRegex = "\\%[a-zA-Z]|\\%\\%|\\%{[^}]*}[a-zA-Z]"
const varModifiedRegex = "\\%{([^}]*)}([a-zA-Z])"
const commonLogDateFormat = "[02/Jan/2006:15:04:05 -0700]"
type logFormatPlaceHolder int
const (
unsupported = iota
remoteHost
clientId
userId
receivedTime
requestLine
statusCode
bytesReturned
bytesReturnedClf
requestHeader
percentSymbol
method
path
puery
processTimeMicro
processTime
)
type logLineTokenType int
const (
textToken = iota
placeholderToken
placeholderWithVar
)
type logLineToken struct {
tokenType logLineTokenType
placeholderType logFormatPlaceHolder
content string
variable string
}
func newTextLogLineElement(text string) *logLineToken {
e := new(logLineToken)
e.tokenType = textToken
e.content = text
return e
}
func newPlaceholderLineElement(phType logFormatPlaceHolder) *logLineToken {
e := new(logLineToken)
e.tokenType = placeholderToken
e.placeholderType = phType
return e
}
func newPlaceholderWithVarLineElement(phType logFormatPlaceHolder, variable string) *logLineToken {
e := new(logLineToken)
e.tokenType = placeholderWithVar
e.placeholderType = phType
e.variable = variable
return e
}
// A component able to asynchronously write an Apache HTTPD style access log. See the top of this GoDoc page for more information.
type AccessLogWriter struct {
logFile *os.File
// The path of the log file to be written to (and created if required)
LogPath string
// The format of each log line. See the top of this GoDoc page for supported formats. Mutually exclusive with LogLinePreset.
LogLineFormat string
// A pre-defined format. Supported values are framework or combined. Mutually exclusive with LogLineFormat.
LogLinePreset string
//The number of lines that can be buffered for asynchronous writing to the log file before calls to LogRequest block.
LineBufferSize int
//Whether or not timestamps should be converted to UTC before they are written to the access log.
UtcTimes bool
elements []*logLineToken
lines chan string
state ioc.ComponentState
}
// LogRequest generates an access log line according the configured format. As long as the number of log lines waiting to
// be written to the file does not exceed the value of AccessLogWriter.LineBufferSize, this method will return immediately.
func (alw *AccessLogWriter) LogRequest(req *http.Request, res *httpendpoint.HttpResponseWriter, rec *time.Time, fin *time.Time, ctx context.Context) {
alw.lines <- alw.buildLine(req, res, rec, fin, ctx)
}
func (alw *AccessLogWriter) buildLine(req *http.Request, res *httpendpoint.HttpResponseWriter, rec *time.Time, fin *time.Time, ctx context.Context) string {
var b bytes.Buffer
if alw.UtcTimes {
utcRec := rec.UTC()
utcFin := fin.UTC()
rec = &utcRec
fin = &utcFin
}
for _, e := range alw.elements {
switch e.tokenType {
case textToken:
b.WriteString(e.content)
case placeholderToken:
b.WriteString(alw.findValue(e, req, res, rec, fin, ctx))
case placeholderWithVar:
b.WriteString(alw.findValueWithVar(e, req, res, rec, fin, ctx))
}
}
b.WriteString("\n")
return b.String()
}
// StartComponent parses the specified log format, sets up a channel to buffer lines for asynchrnous writing and opens the log file. An error
// is returned if any of these steps fails.
func (alw *AccessLogWriter) StartComponent() error {
if alw.state != ioc.StoppedState {
return nil
}
alw.state = ioc.StartingState
alw.lines = make(chan string, alw.LineBufferSize)
err := alw.configureLogFormat()
if err != nil {
return err
}
err = alw.openFile()
go alw.watchLineBuffer()
alw.state = ioc.RunningState
return err
}
func (alw *AccessLogWriter) watchLineBuffer() {
for {
line := <-alw.lines
f := alw.logFile
if f != nil {
f.WriteString(line)
}
}
}
func (alw *AccessLogWriter) openFile() error {
logPath := alw.LogPath
if len(strings.TrimSpace(logPath)) == 0 {
return errors.New("HTTP server access log is enabled, but no path to a log file specified")
}
f, err := os.OpenFile(logPath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
if err != nil {
return err
}
alw.logFile = f
return nil
}
func (alw *AccessLogWriter) configureLogFormat() error {
f := alw.LogLineFormat
pre := alw.LogLinePreset
if f == "" && pre == "" {
return errors.New("You must specify either a format for access log lines or the name of a preset format (neither has been provided).")
}
if f != "" && pre != "" {
return errors.New("You must specify either a format for access log lines OR the name of a preset format (BOTH have been provided).")
}
if pre != "" {
if pre == presetCommonName {
return alw.parseFormat(presetCommonFormat)
} else if pre == presetCombinedName {
return alw.parseFormat(PresetCombinedFormat)
} else if pre == presetframeworkName {
return alw.parseFormat(PresetFrameworkFormat)
} else {
message := fmt.Sprintf("%s is not a supported preset for access log lines", pre)
return errors.New(message)
}
}
return alw.parseFormat(f)
}
func (alw *AccessLogWriter) parseFormat(format string) error {
lineRe := regexp.MustCompile(formatRegex)
varRe := regexp.MustCompile(varModifiedRegex)
placeholders := lineRe.FindAllString(format, -1)
textFragments := lineRe.Split(format, -1)
firstMatch := lineRe.FindStringIndex(format)
var startsWithPh bool
if len(firstMatch) > 0 {
startsWithPh = (firstMatch[0] == 0) && textFragments[0] != ""
}
phCount := len(placeholders)
tCount := len(textFragments)
maxCount := intMax(phCount, tCount)
for i := 0; i < maxCount; i++ {
phAvail := i < phCount
tAvail := i < tCount
var err error
if phAvail && tAvail {
ph := placeholders[i]
text := textFragments[i]
if startsWithPh {
err = alw.addPlaceholder(ph, varRe)
alw.addTextElement(text)
} else {
alw.addTextElement(text)
err = alw.addPlaceholder(ph, varRe)
}
} else if phAvail {
ph := placeholders[i]
err = alw.addPlaceholder(ph, varRe)
} else if tAvail {
text := textFragments[i]
alw.addTextElement(text)
}
if err != nil {
return err
}
}
return nil
}
func (alw *AccessLogWriter) addTextElement(text string) {
if text != "" {
e := newTextLogLineElement(text)
alw.elements = append(alw.elements, e)
}
}
func (alw *AccessLogWriter) addPlaceholder(ph string, re *regexp.Regexp) error {
if len(ph) == 2 {
formatTypeCode := ph[1:2]
lfph := alw.mapPlaceholder(formatTypeCode)
if lfph == unsupported {
message := fmt.Sprintf("%s is not a supported field for formatting access log lines", ph)
return errors.New(message)
} else {
e := newPlaceholderLineElement(lfph)
alw.elements = append(alw.elements, e)
}
} else {
v := re.FindStringSubmatch(ph)
arg := v[1]
formatTypeCode := v[2]
lfph := alw.mapPlaceholder(formatTypeCode)
if lfph == unsupported {
message := fmt.Sprintf("%s is not a supported field for formatting access log lines", ph)
return errors.New(message)
} else {
e := newPlaceholderWithVarLineElement(lfph, arg)
alw.elements = append(alw.elements, e)
}
}
return nil
}
func intMax(x, y int) int {
if x > y {
return x
} else {
return y
}
}
func (alw *AccessLogWriter) mapPlaceholder(ph string) logFormatPlaceHolder {
switch ph {
default:
return unsupported
case "%":
return percentSymbol
case "b":
return bytesReturnedClf
case "B":
return bytesReturned
case "D":
return processTimeMicro
case "h":
return remoteHost
case "i":
return requestHeader
case "l":
return clientId
case "m":
return method
case "q":
return puery
case "r":
return requestLine
case "s":
return statusCode
case "t":
return receivedTime
case "T":
return processTime
case "u":
return userId
case "U":
return path
}
}
func (alw *AccessLogWriter) findValueWithVar(element *logLineToken, req *http.Request, res *httpendpoint.HttpResponseWriter, received *time.Time, finished *time.Time, ctx context.Context) string {
switch element.placeholderType {
case requestHeader:
return alw.requestHeader(element.variable, req)
case receivedTime:
return received.Format(element.variable)
case processTime:
switch element.variable {
case "s":
return alw.processTime(received, finished, time.Second)
case "us":
return alw.processTime(received, finished, time.Microsecond)
case "ms":
return alw.processTime(received, finished, time.Millisecond)
default:
return "??"
}
default:
return unsupportedPlaceholder
}
}
func (alw *AccessLogWriter) findValue(element *logLineToken, req *http.Request, res *httpendpoint.HttpResponseWriter, received *time.Time, finished *time.Time, ctx context.Context) string {
switch element.placeholderType {
case percentSymbol:
return percent
case bytesReturnedClf:
if res.BytesServed == 0 {
return hyphen
} else {
return (strconv.Itoa(res.BytesServed))
}
case bytesReturned:
return (strconv.Itoa(res.BytesServed))
case remoteHost:
return req.RemoteAddr
case clientId:
return hyphen
case userId:
return alw.userId(ctx)
case method:
return req.Method
case path:
return req.URL.Path
case puery:
return alw.query(req)
case requestLine:
return alw.requestLine(req)
case receivedTime:
return received.Format(commonLogDateFormat)
case statusCode:
return strconv.Itoa(res.Status)
case processTimeMicro:
return alw.processTime(received, finished, time.Microsecond)
case processTime:
return alw.processTime(received, finished, time.Second)
default:
return unsupportedPlaceholder
}
}
func (alw *AccessLogWriter) processTime(rec *time.Time, fin *time.Time, unit time.Duration) string {
spent := fin.Sub(*rec)
return strconv.FormatInt(int64(spent/unit), 10)
}
func (alw *AccessLogWriter) query(req *http.Request) string {
q := req.URL.RawQuery
if q == "" {
return q
} else {
return "?" + q
}
}
func (alw *AccessLogWriter) requestHeader(name string, req *http.Request) string {
value := req.Header.Get(name)
if value == "" {
return hyphen
} else {
return value
}
}
func (alw *AccessLogWriter) requestLine(req *http.Request) string {
return fmt.Sprintf("%s %s %s", req.Method, req.RequestURI, req.Proto)
}
func (alw *AccessLogWriter) userId(ctx context.Context) string {
return hyphen
}
// PrepareToStop settings state to 'Stopping'
func (alw *AccessLogWriter) PrepareToStop() {
alw.state = ioc.StoppingState
}
// ReadyToStop always returns true
func (alw *AccessLogWriter) ReadyToStop() (bool, error) {
return true, nil
}
// Stop closes the log file
func (alw *AccessLogWriter) Stop() error {
if alw.logFile != nil {
return alw.logFile.Close()
}
alw.state = ioc.StoppedState
return nil
}