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log.go
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log.go
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package log
import (
"context"
"fmt"
"net/http"
"os"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/weaveworks/common/logging"
"github.com/weaveworks/common/server"
"google.golang.org/grpc/metadata"
)
type contextKey int
const (
headerMapContextKey contextKey = 0
HeaderPropagationStringForRequestLogging string = "x-http-header-forwarding-logging"
)
var (
// Logger is a shared go-kit logger.
// TODO: Change all components to take a non-global logger via their constructors.
// Prefer accepting a non-global logger as an argument.
Logger = log.NewNopLogger()
logMessages = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "log_messages_total",
Help: "Total number of log messages.",
}, []string{"level"})
supportedLevels = []level.Value{
level.DebugValue(),
level.InfoValue(),
level.WarnValue(),
level.ErrorValue(),
}
)
func init() {
prometheus.MustRegister(logMessages)
}
// InitLogger initialises the global gokit logger (util_log.Logger) and overrides the
// default logger for the server.
func InitLogger(cfg *server.Config) {
l := newLoggerWithFormat(cfg.LogFormat)
// when use util_log.Logger, skip 6 stack frames.
Logger = newPrometheusLoggerFrom(l, cfg.LogLevel, "caller", log.Caller(6))
// cfg.Log wraps log function, skip 7 stack frames to get caller information.
// this works in go 1.12, but doesn't work in versions earlier.
// it will always shows the wrapper function generated by compiler
// marked <autogenerated> in old versions.
cfg.Log = logging.GoKit(newPrometheusLoggerFrom(l, cfg.LogLevel, "caller", log.Caller(7)))
}
// PrometheusLogger exposes Prometheus counters for each of go-kit's log levels.
type PrometheusLogger struct {
logger log.Logger
}
// NewPrometheusLogger creates a new instance of PrometheusLogger which exposes
// Prometheus counters for various log levels.
func NewPrometheusLogger(l logging.Level, format logging.Format) (log.Logger, error) {
logger := newLoggerWithFormat(format)
return newPrometheusLoggerFrom(logger, l), nil
}
func newLoggerWithFormat(format logging.Format) log.Logger {
logger := log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
if format.String() == "json" {
logger = log.NewJSONLogger(log.NewSyncWriter(os.Stderr))
}
return logger
}
func newPrometheusLoggerFrom(logger log.Logger, logLevel logging.Level, keyvals ...interface{}) log.Logger {
// Sort the logger chain to avoid expensive log.Valuer evaluation for disallowed level.
// Ref: https://github.com/go-kit/log/issues/14#issuecomment-945038252
logger = log.With(logger, "ts", log.DefaultTimestampUTC)
logger = log.With(logger, keyvals...)
logger = level.NewFilter(logger, LevelFilter(logLevel.String()))
// Initialise counters for all supported levels:
for _, level := range supportedLevels {
logMessages.WithLabelValues(level.String())
}
return &PrometheusLogger{
logger: logger,
}
}
// Log increments the appropriate Prometheus counter depending on the log level.
func (pl *PrometheusLogger) Log(kv ...interface{}) error {
pl.logger.Log(kv...)
l := "unknown"
for i := 1; i < len(kv); i += 2 {
if v, ok := kv[i].(level.Value); ok {
l = v.String()
break
}
}
logMessages.WithLabelValues(l).Inc()
return nil
}
// CheckFatal prints an error and exits with error code 1 if err is non-nil
func CheckFatal(location string, err error) {
if err != nil {
logger := level.Error(Logger)
if location != "" {
logger = log.With(logger, "msg", "error "+location)
}
// %+v gets the stack trace from errors using github.com/pkg/errors
logger.Log("err", fmt.Sprintf("%+v", err))
os.Exit(1)
}
}
// TODO(dannyk): remove once weaveworks/common updates to go-kit/log
//
// -> we can then revert to using Level.Gokit
func LevelFilter(l string) level.Option {
switch l {
case "debug":
return level.AllowDebug()
case "info":
return level.AllowInfo()
case "warn":
return level.AllowWarn()
case "error":
return level.AllowError()
default:
return level.AllowAll()
}
}
func HeaderMapFromContext(ctx context.Context) map[string]string {
headerMap, ok := ctx.Value(headerMapContextKey).(map[string]string)
if !ok {
return nil
}
return headerMap
}
func ContextWithHeaderMap(ctx context.Context, headerMap map[string]string) context.Context {
return context.WithValue(ctx, headerMapContextKey, headerMap)
}
// InjectHeadersIntoHTTPRequest injects the logging header map from the context into the request headers.
func InjectHeadersIntoHTTPRequest(headerMap map[string]string, request *http.Request) {
for header, contents := range headerMap {
request.Header.Add(header, contents)
}
}
func ContextWithHeaderMapFromMetadata(ctx context.Context, md metadata.MD) context.Context {
headersSlice, ok := md[HeaderPropagationStringForRequestLogging]
if !ok || len(headersSlice)%2 == 1 {
return ctx
}
headerMap := make(map[string]string)
for i := 0; i < len(headersSlice); i += 2 {
headerMap[headersSlice[i]] = headersSlice[i+1]
}
return ContextWithHeaderMap(ctx, headerMap)
}