open-consul/vendor/github.com/Azure/go-autorest/logger/logger.go

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package logger
// Copyright 2017 Microsoft Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"os"
"strings"
"sync"
"time"
)
// LevelType tells a logger the minimum level to log. When code reports a log entry,
// the LogLevel indicates the level of the log entry. The logger only records entries
// whose level is at least the level it was told to log. See the Log* constants.
// For example, if a logger is configured with LogError, then LogError, LogPanic,
// and LogFatal entries will be logged; lower level entries are ignored.
type LevelType uint32
const (
// LogNone tells a logger not to log any entries passed to it.
LogNone LevelType = iota
// LogFatal tells a logger to log all LogFatal entries passed to it.
LogFatal
// LogPanic tells a logger to log all LogPanic and LogFatal entries passed to it.
LogPanic
// LogError tells a logger to log all LogError, LogPanic and LogFatal entries passed to it.
LogError
// LogWarning tells a logger to log all LogWarning, LogError, LogPanic and LogFatal entries passed to it.
LogWarning
// LogInfo tells a logger to log all LogInfo, LogWarning, LogError, LogPanic and LogFatal entries passed to it.
LogInfo
// LogDebug tells a logger to log all LogDebug, LogInfo, LogWarning, LogError, LogPanic and LogFatal entries passed to it.
LogDebug
)
const (
logNone = "NONE"
logFatal = "FATAL"
logPanic = "PANIC"
logError = "ERROR"
logWarning = "WARNING"
logInfo = "INFO"
logDebug = "DEBUG"
logUnknown = "UNKNOWN"
)
// ParseLevel converts the specified string into the corresponding LevelType.
func ParseLevel(s string) (lt LevelType, err error) {
switch strings.ToUpper(s) {
case logFatal:
lt = LogFatal
case logPanic:
lt = LogPanic
case logError:
lt = LogError
case logWarning:
lt = LogWarning
case logInfo:
lt = LogInfo
case logDebug:
lt = LogDebug
default:
err = fmt.Errorf("bad log level '%s'", s)
}
return
}
// String implements the stringer interface for LevelType.
func (lt LevelType) String() string {
switch lt {
case LogNone:
return logNone
case LogFatal:
return logFatal
case LogPanic:
return logPanic
case LogError:
return logError
case LogWarning:
return logWarning
case LogInfo:
return logInfo
case LogDebug:
return logDebug
default:
return logUnknown
}
}
// Filter defines functions for filtering HTTP request/response content.
type Filter struct {
// URL returns a potentially modified string representation of a request URL.
URL func(u *url.URL) string
// Header returns a potentially modified set of values for the specified key.
// To completely exclude the header key/values return false.
Header func(key string, val []string) (bool, []string)
// Body returns a potentially modified request/response body.
Body func(b []byte) []byte
}
func (f Filter) processURL(u *url.URL) string {
if f.URL == nil {
return u.String()
}
return f.URL(u)
}
func (f Filter) processHeader(k string, val []string) (bool, []string) {
if f.Header == nil {
return true, val
}
return f.Header(k, val)
}
func (f Filter) processBody(b []byte) []byte {
if f.Body == nil {
return b
}
return f.Body(b)
}
// Writer defines methods for writing to a logging facility.
type Writer interface {
// Writeln writes the specified message with the standard log entry header and new-line character.
Writeln(level LevelType, message string)
// Writef writes the specified format specifier with the standard log entry header and no new-line character.
Writef(level LevelType, format string, a ...interface{})
// WriteRequest writes the specified HTTP request to the logger if the log level is greater than
// or equal to LogInfo. The request body, if set, is logged at level LogDebug or higher.
// Custom filters can be specified to exclude URL, header, and/or body content from the log.
// By default no request content is excluded.
WriteRequest(req *http.Request, filter Filter)
// WriteResponse writes the specified HTTP response to the logger if the log level is greater than
// or equal to LogInfo. The response body, if set, is logged at level LogDebug or higher.
// Custom filters can be specified to exclude URL, header, and/or body content from the log.
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// By default no response content is excluded.
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WriteResponse(resp *http.Response, filter Filter)
}
// Instance is the default log writer initialized during package init.
// This can be replaced with a custom implementation as required.
var Instance Writer
// default log level
var logLevel = LogNone
// Level returns the value specified in AZURE_GO_AUTOREST_LOG_LEVEL.
// If no value was specified the default value is LogNone.
// Custom loggers can call this to retrieve the configured log level.
func Level() LevelType {
return logLevel
}
func init() {
// separated for testing purposes
initDefaultLogger()
}
func initDefaultLogger() {
// init with nilLogger so callers don't have to do a nil check on Default
Instance = nilLogger{}
llStr := strings.ToLower(os.Getenv("AZURE_GO_SDK_LOG_LEVEL"))
if llStr == "" {
return
}
var err error
logLevel, err = ParseLevel(llStr)
if err != nil {
fmt.Fprintf(os.Stderr, "go-autorest: failed to parse log level: %s\n", err.Error())
return
}
if logLevel == LogNone {
return
}
// default to stderr
dest := os.Stderr
lfStr := os.Getenv("AZURE_GO_SDK_LOG_FILE")
if strings.EqualFold(lfStr, "stdout") {
dest = os.Stdout
} else if lfStr != "" {
lf, err := os.Create(lfStr)
if err == nil {
dest = lf
} else {
fmt.Fprintf(os.Stderr, "go-autorest: failed to create log file, using stderr: %s\n", err.Error())
}
}
Instance = fileLogger{
logLevel: logLevel,
mu: &sync.Mutex{},
logFile: dest,
}
}
// the nil logger does nothing
type nilLogger struct{}
func (nilLogger) Writeln(LevelType, string) {}
func (nilLogger) Writef(LevelType, string, ...interface{}) {}
func (nilLogger) WriteRequest(*http.Request, Filter) {}
func (nilLogger) WriteResponse(*http.Response, Filter) {}
// A File is used instead of a Logger so the stream can be flushed after every write.
type fileLogger struct {
logLevel LevelType
mu *sync.Mutex // for synchronizing writes to logFile
logFile *os.File
}
func (fl fileLogger) Writeln(level LevelType, message string) {
fl.Writef(level, "%s\n", message)
}
func (fl fileLogger) Writef(level LevelType, format string, a ...interface{}) {
if fl.logLevel >= level {
fl.mu.Lock()
defer fl.mu.Unlock()
fmt.Fprintf(fl.logFile, "%s %s", entryHeader(level), fmt.Sprintf(format, a...))
fl.logFile.Sync()
}
}
func (fl fileLogger) WriteRequest(req *http.Request, filter Filter) {
if req == nil || fl.logLevel < LogInfo {
return
}
b := &bytes.Buffer{}
fmt.Fprintf(b, "%s REQUEST: %s %s\n", entryHeader(LogInfo), req.Method, filter.processURL(req.URL))
// dump headers
for k, v := range req.Header {
if ok, mv := filter.processHeader(k, v); ok {
fmt.Fprintf(b, "%s: %s\n", k, strings.Join(mv, ","))
}
}
if fl.shouldLogBody(req.Header, req.Body) {
// dump body
body, err := ioutil.ReadAll(req.Body)
if err == nil {
fmt.Fprintln(b, string(filter.processBody(body)))
if nc, ok := req.Body.(io.Seeker); ok {
// rewind to the beginning
nc.Seek(0, io.SeekStart)
} else {
// recreate the body
req.Body = ioutil.NopCloser(bytes.NewReader(body))
}
} else {
fmt.Fprintf(b, "failed to read body: %v\n", err)
}
}
fl.mu.Lock()
defer fl.mu.Unlock()
fmt.Fprint(fl.logFile, b.String())
fl.logFile.Sync()
}
func (fl fileLogger) WriteResponse(resp *http.Response, filter Filter) {
if resp == nil || fl.logLevel < LogInfo {
return
}
b := &bytes.Buffer{}
fmt.Fprintf(b, "%s RESPONSE: %d %s\n", entryHeader(LogInfo), resp.StatusCode, filter.processURL(resp.Request.URL))
// dump headers
for k, v := range resp.Header {
if ok, mv := filter.processHeader(k, v); ok {
fmt.Fprintf(b, "%s: %s\n", k, strings.Join(mv, ","))
}
}
if fl.shouldLogBody(resp.Header, resp.Body) {
// dump body
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err == nil {
fmt.Fprintln(b, string(filter.processBody(body)))
resp.Body = ioutil.NopCloser(bytes.NewReader(body))
} else {
fmt.Fprintf(b, "failed to read body: %v\n", err)
}
}
fl.mu.Lock()
defer fl.mu.Unlock()
fmt.Fprint(fl.logFile, b.String())
fl.logFile.Sync()
}
// returns true if the provided body should be included in the log
func (fl fileLogger) shouldLogBody(header http.Header, body io.ReadCloser) bool {
ct := header.Get("Content-Type")
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return fl.logLevel >= LogDebug && body != nil && !strings.Contains(ct, "application/octet-stream")
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}
// creates standard header for log entries, it contains a timestamp and the log level
func entryHeader(level LevelType) string {
// this format provides a fixed number of digits so the size of the timestamp is constant
return fmt.Sprintf("(%s) %s:", time.Now().Format("2006-01-02T15:04:05.0000000Z07:00"), level.String())
}