Merge pull request #2209 from bradrydzewski/master

Provide a basic agent healthcheck

Dockerfile.agent

@@ -1,7 +1,11 @@
-# docker build --rm -t drone/drone .
+# docker build --rm -f Dockerfile.agent -t drone/agent .
+
+EXPOSE 3000
 
 FROM centurylink/ca-certs
 ENV GODEBUG=netdns=go
 ADD release/drone-agent /bin/
 
+HEALTHCHECK CMD ["/bin/drone-agent", "ping"]
+
 ENTRYPOINT ["/bin/drone-agent"]

Dockerfile.agent.linux.arm

@@ -1,5 +1,3 @@
-# docker build --rm -t drone/drone .
-
 FROM centurylink/ca-certs
 ENV GODEBUG=netdns=go
 ENV DRONE_PLATFORM=linux/arm

Dockerfile.agent.linux.arm64

@@ -1,5 +1,3 @@
-# docker build --rm -t drone/drone .
-
 FROM centurylink/ca-certs
 ENV GODEBUG=netdns=go
 ENV DRONE_PLATFORM=linux/arm64

cmd/drone-agent/agent.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"io"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"strconv"
 	"sync"
@@ -46,6 +47,22 @@ func loop(c *cli.Context) error {
 		zerolog.SetGlobalLevel(zerolog.WarnLevel)
 	}
 
+	if c.Bool("pretty") {
+		log.Logger = log.Output(
+			zerolog.ConsoleWriter{
+				Out:     os.Stderr,
+				NoColor: c.BoolT("nocolor"),
+			},
+		)
+	}
+
+	counter.Polling = c.Int("max-procs")
+	counter.Running = 0
+
+	if c.BoolT("healthcheck") {
+		go http.ListenAndServe(":3000", nil)
+	}
+
 	// TODO pass version information to grpc server
 	// TODO authenticate to grpc server
 
@@ -124,9 +141,22 @@ func run(ctx context.Context, client rpc.Peer, filter rpc.Filter) error {
 		return nil
 	}
 
+	timeout := time.Hour
+	if minutes := work.Timeout; minutes != 0 {
+		timeout = time.Duration(minutes) * time.Minute
+	}
+
+	counter.Add(
+		work.ID,
+		timeout,
+		extractRepositoryName(work.Config), // hack
+		extractBuildNumber(work.Config),    // hack
+	)
+	defer counter.Done(work.ID)
+
 	logger := log.With().
-		Str("repo", extractRepositoryName(work.Config)).
-		Str("build", extractBuildNumber(work.Config)).
+		Str("repo", extractRepositoryName(work.Config)). // hack
+		Str("build", extractBuildNumber(work.Config)).   // hack
 		Str("id", work.ID).
 		Logger()
 
@@ -143,11 +173,6 @@ func run(ctx context.Context, client rpc.Peer, filter rpc.Filter) error {
 		return err
 	}
 
-	timeout := time.Hour
-	if minutes := work.Timeout; minutes != 0 {
-		timeout = time.Duration(minutes) * time.Minute
-	}
-
 	ctx, cancel := context.WithTimeout(ctxmeta, timeout)
 	defer cancel()
 

cmd/drone-agent/health.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/drone/drone/version"
+	"github.com/urfave/cli"
+)
+
+// the file implements some basic healthcheck logic based on the
+// following specification:
+//   https://github.com/mozilla-services/Dockerflow
+
+func init() {
+	http.HandleFunc("/varz", handleStats)
+	http.HandleFunc("/healthz", handleHeartbeat)
+	http.HandleFunc("/version", handleVersion)
+}
+
+func handleHeartbeat(w http.ResponseWriter, r *http.Request) {
+	if counter.Healthy() {
+		w.WriteHeader(200)
+	} else {
+		w.WriteHeader(500)
+	}
+}
+
+func handleVersion(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(200)
+	w.Header().Add("Content-Type", "text/json")
+	json.NewEncoder(w).Encode(versionResp{
+		Source:  "https://github.com/drone/drone",
+		Version: version.Version.String(),
+	})
+}
+
+func handleStats(w http.ResponseWriter, r *http.Request) {
+	if counter.Healthy() {
+		w.WriteHeader(200)
+	} else {
+		w.WriteHeader(500)
+	}
+	w.Header().Add("Content-Type", "text/json")
+	counter.writeTo(w)
+}
+
+type versionResp struct {
+	Version string `json:"version"`
+	Source  string `json:"source"`
+}
+
+// default statistics counter
+var counter = &state{
+	Metadata: map[string]info{},
+}
+
+type state struct {
+	sync.Mutex `json:"-"`
+	Polling    int             `json:"polling_count"`
+	Running    int             `json:"running_count"`
+	Metadata   map[string]info `json:"running"`
+}
+
+type info struct {
+	ID      string        `json:"id"`
+	Repo    string        `json:"repository"`
+	Build   string        `json:"build_number"`
+	Started time.Time     `json:"build_started"`
+	Timeout time.Duration `json:"build_timeout"`
+}
+
+func (s *state) Add(id string, timeout time.Duration, repo, build string) {
+	s.Lock()
+	s.Polling--
+	s.Running++
+	s.Metadata[id] = info{
+		ID:      id,
+		Repo:    repo,
+		Build:   build,
+		Timeout: timeout,
+		Started: time.Now().UTC(),
+	}
+	s.Unlock()
+}
+
+func (s *state) Done(id string) {
+	s.Lock()
+	s.Polling++
+	s.Running--
+	delete(s.Metadata, id)
+	s.Unlock()
+}
+
+func (s *state) Healthy() bool {
+	s.Lock()
+	defer s.Unlock()
+	now := time.Now()
+	buf := time.Hour // 1 hour buffer
+	for _, item := range s.Metadata {
+		if now.After(item.Started.Add(item.Timeout).Add(buf)) {
+			return false
+		}
+	}
+	return true
+}
+
+func (s *state) writeTo(w io.Writer) (int, error) {
+	s.Lock()
+	out, _ := json.Marshal(s)
+	s.Unlock()
+	return w.Write(out)
+}
+
+// handles pinging the endpoint and returns an error if the
+// agent is in an unhealthy state.
+func pinger(c *cli.Context) error {
+	resp, err := http.Get("http://localhost:3000/healthz")
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("agent returned non-200 status code")
+	}
+	return nil
+}

cmd/drone-agent/health_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestHealthy(t *testing.T) {
+	s := state{}
+	s.Metadata = map[string]info{}
+
+	s.Add("1", time.Hour, "octocat/hello-world", "42")
+
+	if got, want := s.Metadata["1"].ID, "1"; got != want {
+		t.Errorf("got ID %s, want %s", got, want)
+	}
+	if got, want := s.Metadata["1"].Timeout, time.Hour; got != want {
+		t.Errorf("got duration %v, want %v", got, want)
+	}
+	if got, want := s.Metadata["1"].Repo, "octocat/hello-world"; got != want {
+		t.Errorf("got repository name %s, want %s", got, want)
+	}
+
+	s.Metadata["1"] = info{
+		Timeout: time.Hour,
+		Started: time.Now().UTC(),
+	}
+	if s.Healthy() == false {
+		t.Error("want healthy status when timeout not exceeded, got false")
+	}
+
+	s.Metadata["1"] = info{
+		Started: time.Now().UTC().Add(-(time.Minute * 30)),
+	}
+	if s.Healthy() == false {
+		t.Error("want healthy status when timeout+buffer not exceeded, got false")
+	}
+
+	s.Metadata["1"] = info{
+		Started: time.Now().UTC().Add(-(time.Hour + time.Minute)),
+	}
+	if s.Healthy() == true {
+		t.Error("want unhealthy status when timeout+buffer not exceeded, got true")
+	}
+}

cmd/drone-agent/main.go

@@ -16,6 +16,13 @@ func main() {
 	app.Version = version.Version.String()
 	app.Usage = "drone agent"
 	app.Action = loop
+	app.Commands = []cli.Command{
+		{
+			Name:   "ping",
+			Usage:  "ping the agent",
+			Action: pinger,
+		},
+	}
 	app.Flags = []cli.Flag{
 		cli.StringFlag{
 			EnvVar: "DRONE_SERVER",
@@ -39,6 +46,16 @@ func main() {
 			Name:   "debug",
 			Usage:  "start the agent in debug mode",
 		},
+		cli.BoolFlag{
+			EnvVar: "DRONE_DEBUG_PRETTY",
+			Name:   "pretty",
+			Usage:  "enable pretty-printed debug output",
+		},
+		cli.BoolTFlag{
+			EnvVar: "DRONE_DEBUG_NOCOLOR",
+			Name:   "nocolor",
+			Usage:  "disable colored debug output",
+		},
 		cli.StringFlag{
 			EnvVar: "DRONE_HOSTNAME,HOSTNAME",
 			Name:   "hostname",
@@ -50,14 +67,19 @@ func main() {
 		},
 		cli.StringFlag{
 			EnvVar: "DRONE_FILTER",
-			Name:   "drone-filter",
-			Usage:  "A filter expression used to restrict builds by label",
+			Name:   "filter",
+			Usage:  "filter expression used to restrict builds by label",
 		},
 		cli.IntFlag{
 			EnvVar: "DRONE_MAX_PROCS",
 			Name:   "max-procs",
 			Value:  1,
 		},
+		cli.BoolTFlag{
+			EnvVar: "DRONE_HEALTHCHECK",
+			Name:   "healthcheck",
+			Usage:  "enables the healthcheck endpoint",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {

vendor/github.com/rs/zerolog/README.md

@@ -8,16 +8,20 @@ Zerolog's API is designed to provide both a great developer experience and stunn
 
 The uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with simpler to use API and even better performance.
 
-To keep the code base and the API simple, zerolog focuses on JSON logging only. As [suggested on reddit](https://www.reddit.com/r/golang/comments/6c9k7n/zerolog_is_now_faster_than_zap/), you may use tools like [humanlog](https://github.com/aybabtme/humanlog) to pretty print JSON on the console during development.
+To keep the code base and the API simple, zerolog focuses on JSON logging only. Pretty logging on the console is made possible using the provided (but inefficient) `zerolog.ConsoleWriter`.
 
+![](pretty.png)
 
 ## Features
 
+* Blazing fast
+* Low to zero allocation
 * Level logging
 * Sampling
 * Contextual fields
 * `context.Context` integration
 * `net/http` helpers
+* Pretty logging for development
 
 ## Usage
 
@@ -27,6 +31,13 @@ import "github.com/rs/zerolog/log"
 
 ### A global logger can be use for simple logging
 
+```go
+log.Print("hello world")
+
+// Output: {"level":"debug","time":1494567715,"message":"hello world"}
+```
+
+
 ```go
 log.Info().Msg("hello world")
 
@@ -96,6 +107,18 @@ if e := log.Debug(); e.Enabled() {
 // Output: {"level":"info","time":1494567715,"message":"routed message"}
 ```
 
+### Pretty logging
+
+```go
+if isConsole {
+    log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+}
+
+log.Info().Str("foo", "bar").Msg("Hello world")
+
+// Output: 1494567715 |INFO| Hello world foo=bar
+```
+
 ### Sub dictionary
 
 ```go
@@ -138,12 +161,31 @@ log.Logger = log.With().Str("foo", "bar").Logger()
 ### Log Sampling
 
 ```go
-sampled := log.Sample(10)
+sampled := log.Sample(&zerolog.BasicSampler{N: 10})
 sampled.Info().Msg("will be logged every 10 messages")
 
-// Output: {"time":1494567715,"sample":10,"message":"will be logged every 10 messages"}
+// Output: {"time":1494567715,"level":"info","message":"will be logged every 10 messages"}
 ```
 
+More advanced sampling:
+
+```go
+// Will let 5 debug messages per period of 1 second.
+// Over 5 debug message, 1 every 100 debug messages are logged.
+// Other levels are not sampled.
+sampled := log.Sample(zerolog.LevelSampler{
+    DebugSampler: &zerolog.BurstSampler{
+        Burst: 5,
+        Period: 1*time.Second,
+        NextSampler: &zerolog.BasicSampler{N: 100},
+    },
+})
+sampled.Debug().Msg("hello world")
+
+// Output: {"time":1494567715,"level":"debug","message":"hello world"}
+```
+
+
 ### Pass a sub-logger by context
 
 ```go
@@ -233,7 +275,6 @@ Some settings can be changed and will by applied to all loggers:
 * `zerolog.LevelFieldName`: Can be set to customize level field name.
 * `zerolog.MessageFieldName`: Can be set to customize message field name.
 * `zerolog.ErrorFieldName`: Can be set to customize `Err` field name.
-* `zerolog.SampleFieldName`: Can be set to customize the field name added when sampling is enabled.
 * `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with an empty string, times are formated as UNIX timestamp.
 	// DurationFieldUnit defines the unit for time.Duration type fields added
 	// using the Dur method.
@@ -259,7 +300,7 @@ Some settings can be changed and will by applied to all loggers:
 * `Dict`: Adds a sub-key/value as a field of the event.
 * `Interface`: Uses reflection to marshal the type.
 
-## Performance
+## Benchmarks
 
 All operations are allocation free (those numbers *include* JSON encoding):
 
@@ -271,7 +312,12 @@ BenchmarkContextFields-8   30000000	    44.9 ns/op	   0 B/op       0 allocs/op
 BenchmarkLogFields-8       10000000	   184 ns/op	   0 B/op       0 allocs/op
 ```
 
-Using Uber's zap [comparison benchmark](https://github.com/uber-go/zap#performance):
+There are a few Go logging benchmarks and comparisons that include zerolog.
+
+- [imkira/go-loggers-bench](https://github.com/imkira/go-loggers-bench)
+- [uber-common/zap](https://github.com/uber-go/zap#performance)
+
+Using Uber's zap comparison benchmark:
 
 Log a message and 10 fields:
 

vendor/github.com/rs/zerolog/console.go

@@ -0,0 +1,117 @@
+package zerolog
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+const (
+	cReset    = 0
+	cBold     = 1
+	cRed      = 31
+	cGreen    = 32
+	cYellow   = 33
+	cBlue     = 34
+	cMagenta  = 35
+	cCyan     = 36
+	cGray     = 37
+	cDarkGray = 90
+)
+
+var consoleBufPool = sync.Pool{
+	New: func() interface{} {
+		return bytes.NewBuffer(make([]byte, 0, 100))
+	},
+}
+
+// ConsoleWriter reads a JSON object per write operation and output an
+// optionally colored human readable version on the Out writer.
+type ConsoleWriter struct {
+	Out     io.Writer
+	NoColor bool
+}
+
+func (w ConsoleWriter) Write(p []byte) (n int, err error) {
+	var event map[string]interface{}
+	err = json.Unmarshal(p, &event)
+	if err != nil {
+		return
+	}
+	buf := consoleBufPool.Get().(*bytes.Buffer)
+	defer consoleBufPool.Put(buf)
+	lvlColor := cReset
+	level := "????"
+	if l, ok := event[LevelFieldName].(string); ok {
+		if !w.NoColor {
+			lvlColor = levelColor(l)
+		}
+		level = strings.ToUpper(l)[0:4]
+	}
+	fmt.Fprintf(buf, "%s |%s| %s",
+		colorize(event[TimestampFieldName], cDarkGray, !w.NoColor),
+		colorize(level, lvlColor, !w.NoColor),
+		colorize(event[MessageFieldName], cReset, !w.NoColor))
+	fields := make([]string, 0, len(event))
+	for field := range event {
+		switch field {
+		case LevelFieldName, TimestampFieldName, MessageFieldName:
+			continue
+		}
+		fields = append(fields, field)
+	}
+	sort.Strings(fields)
+	for _, field := range fields {
+		fmt.Fprintf(buf, " %s=", colorize(field, cCyan, !w.NoColor))
+		switch value := event[field].(type) {
+		case string:
+			if needsQuote(value) {
+				buf.WriteString(strconv.Quote(value))
+			} else {
+				buf.WriteString(value)
+			}
+		default:
+			fmt.Fprint(buf, value)
+		}
+	}
+	buf.WriteByte('\n')
+	buf.WriteTo(w.Out)
+	n = len(p)
+	return
+}
+
+func colorize(s interface{}, color int, enabled bool) string {
+	if !enabled {
+		return fmt.Sprintf("%v", s)
+	}
+	return fmt.Sprintf("\x1b[%dm%v\x1b[0m", color, s)
+}
+
+func levelColor(level string) int {
+	switch level {
+	case "debug":
+		return cMagenta
+	case "info":
+		return cGreen
+	case "warn":
+		return cYellow
+	case "error", "fatal", "panic":
+		return cRed
+	default:
+		return cReset
+	}
+}
+
+func needsQuote(s string) bool {
+	for i := range s {
+		if s[i] < 0x20 || s[i] > 0x7e || s[i] == ' ' || s[i] == '\\' || s[i] == '"' {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/rs/zerolog/ctx.go

@@ -5,25 +5,42 @@ import (
 	"io/ioutil"
 )
 
-var disabledLogger = New(ioutil.Discard).Level(Disabled)
+var disabledLogger *Logger
+
+func init() {
+	l := New(ioutil.Discard).Level(Disabled)
+	disabledLogger = &l
+}
 
 type ctxKey struct{}
 
-// WithContext returns a copy of ctx with l associated.
+// WithContext returns a copy of ctx with l associated. If an instance of Logger
+// is already in the context, the pointer to this logger is updated with l.
+//
+// For instance, to add a field to an existing logger in the context, use this
+// notation:
+//
+//     ctx := r.Context()
+//     l := zerolog.Ctx(ctx)
+//     ctx = l.With().Str("foo", "bar").WithContext(ctx)
 func (l Logger) WithContext(ctx context.Context) context.Context {
 	if lp, ok := ctx.Value(ctxKey{}).(*Logger); ok {
 		// Update existing pointer.
 		*lp = l
 		return ctx
 	}
+	if l.level == Disabled {
+		// Do not store disabled logger.
+		return ctx
+	}
 	return context.WithValue(ctx, ctxKey{}, &l)
 }
 
 // Ctx returns the Logger associated with the ctx. If no logger
 // is associated, a disabled logger is returned.
-func Ctx(ctx context.Context) Logger {
+func Ctx(ctx context.Context) *Logger {
 	if l, ok := ctx.Value(ctxKey{}).(*Logger); ok {
-		return *l
+		return l
 	}
 	return disabledLogger
 }

vendor/github.com/rs/zerolog/globals.go

@@ -16,9 +16,6 @@ var (
 	// ErrorFieldName is the field name used for error fields.
 	ErrorFieldName = "error"
 
-	// SampleFieldName is the name of the field used to report sampling.
-	SampleFieldName = "sample"
-
 	// TimeFieldFormat defines the time format of the Time field type.
 	// If set to an empty string, the time is formatted as an UNIX timestamp
 	// as integer.

vendor/github.com/rs/zerolog/log.go

@@ -62,17 +62,17 @@
 //
 // Sample logs:
 //
-//     sampled := log.Sample(10)
+//     sampled := log.Sample(&zerolog.BasicSampler{N: 10})
 //     sampled.Info().Msg("will be logged every 10 messages")
 //
 package zerolog
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"strconv"
-	"sync/atomic"
 
 	"github.com/rs/zerolog/internal/json"
 )
@@ -115,15 +115,6 @@ func (l Level) String() string {
 	return ""
 }
 
-const (
-	// Often samples log every 10 events.
-	Often = 10
-	// Sometimes samples log every 100 events.
-	Sometimes = 100
-	// Rarely samples log every 1000 events.
-	Rarely = 1000
-)
-
 var disabledEvent = newEvent(levelWriterAdapter{ioutil.Discard}, 0, false)
 
 // A Logger represents an active logging object that generates lines
@@ -134,8 +125,7 @@ var disabledEvent = newEvent(levelWriterAdapter{ioutil.Discard}, 0, false)
 type Logger struct {
 	w       LevelWriter
 	level   Level
-	sample  uint32
-	counter *uint32
+	sampler Sampler
 	context []byte
 }
 
@@ -162,6 +152,16 @@ func Nop() Logger {
 	return New(nil).Level(Disabled)
 }
 
+// Output duplicates the current logger and sets w as its output.
+func (l Logger) Output(w io.Writer) Logger {
+	l2 := New(w)
+	l2.level = l.level
+	l2.sampler = l.sampler
+	l2.context = make([]byte, len(l.context), cap(l.context))
+	copy(l2.context, l.context)
+	return l2
+}
+
 // With creates a child logger with the field added to its context.
 func (l Logger) With() Context {
 	context := l.context
@@ -175,34 +175,30 @@ func (l Logger) With() Context {
 	return Context{l}
 }
 
-// Level creates a child logger with the minimum accepted level set to level.
-func (l Logger) Level(lvl Level) Logger {
-	return Logger{
-		w:       l.w,
-		level:   lvl,
-		sample:  l.sample,
-		counter: l.counter,
-		context: l.context,
+// UpdateContext updates the internal logger's context.
+//
+// Use this method with caution. If unsure, prefer the With method.
+func (l *Logger) UpdateContext(update func(c Context) Context) {
+	if l == disabledLogger {
+		return
 	}
+	if cap(l.context) == 0 {
+		l.context = make([]byte, 1, 500) // first byte is timestamp flag
+	}
+	c := update(Context{*l})
+	l.context = c.l.context
 }
 
-// Sample returns a logger that only let one message out of every to pass thru.
-func (l Logger) Sample(every int) Logger {
-	if every == 0 {
-		// Create a child with no sampling.
-		return Logger{
-			w:       l.w,
-			level:   l.level,
-			context: l.context,
-		}
-	}
-	return Logger{
-		w:       l.w,
-		level:   l.level,
-		sample:  uint32(every),
-		counter: new(uint32),
-		context: l.context,
-	}
+// Level creates a child logger with the minimum accepted level set to level.
+func (l Logger) Level(lvl Level) Logger {
+	l.level = lvl
+	return l
+}
+
+// Sample returns a logger with the s sampler.
+func (l Logger) Sample(s Sampler) Logger {
+	l.sampler = s
+	return l
 }
 
 // Debug starts a new message with debug level.
@@ -283,6 +279,22 @@ func (l Logger) Log() *Event {
 	return l.newEvent(PanicLevel, false, nil)
 }
 
+// Print sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Print.
+func (l Logger) Print(v ...interface{}) {
+	if e := l.Debug(); e.Enabled() {
+		e.Msg(fmt.Sprint(v...))
+	}
+}
+
+// Printf sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Printf.
+func (l Logger) Printf(format string, v ...interface{}) {
+	if e := l.Debug(); e.Enabled() {
+		e.Msg(fmt.Sprintf(format, v...))
+	}
+}
+
 // Write implements the io.Writer interface. This is useful to set as a writer
 // for the standard library log.
 func (l Logger) Write(p []byte) (n int, err error) {
@@ -304,7 +316,7 @@ func (l Logger) newEvent(level Level, addLevelField bool, done func(string)) *Ev
 	if addLevelField {
 		lvl = level
 	}
-	e := newEvent(l.w, lvl, enabled)
+	e := newEvent(l.w, lvl, true)
 	e.done = done
 	if l.context != nil && len(l.context) > 0 && l.context[0] > 0 {
 		// first byte of context is ts flag
@@ -313,9 +325,6 @@ func (l Logger) newEvent(level Level, addLevelField bool, done func(string)) *Ev
 	if addLevelField {
 		e.Str(LevelFieldName, level.String())
 	}
-	if l.sample > 0 && SampleFieldName != "" {
-		e.Uint32(SampleFieldName, l.sample)
-	}
 	if l.context != nil && len(l.context) > 1 {
 		if len(e.buf) > 1 {
 			e.buf = append(e.buf, ',')
@@ -330,9 +339,8 @@ func (l Logger) should(lvl Level) bool {
 	if lvl < l.level || lvl < globalLevel() {
 		return false
 	}
-	if l.sample > 0 && l.counter != nil && !samplingDisabled() {
-		c := atomic.AddUint32(l.counter, 1)
-		return c%l.sample == 0
+	if l.sampler != nil && !samplingDisabled() {
+		return l.sampler.Sample(lvl)
 	}
 	return true
 }

vendor/github.com/rs/zerolog/log/log.go

@@ -3,6 +3,7 @@ package log
 
 import (
 	"context"
+	"io"
 	"os"
 
 	"github.com/rs/zerolog"
@@ -11,6 +12,11 @@ import (
 // Logger is the global logger.
 var Logger = zerolog.New(os.Stderr).With().Timestamp().Logger()
 
+// Output duplicates the global logger and sets w as its output.
+func Output(w io.Writer) zerolog.Logger {
+	return Logger.Output(w)
+}
+
 // With creates a child logger with the field added to its context.
 func With() zerolog.Context {
 	return Logger.With()
@@ -21,9 +27,9 @@ func Level(level zerolog.Level) zerolog.Logger {
 	return Logger.Level(level)
 }
 
-// Sample returns a logger that only let one message out of every to pass thru.
-func Sample(every int) zerolog.Logger {
-	return Logger.Sample(every)
+// Sample returns a logger with the s sampler.
+func Sample(s zerolog.Sampler) zerolog.Logger {
+	return Logger.Sample(s)
 }
 
 // Debug starts a new message with debug level.
@@ -78,8 +84,20 @@ func Log() *zerolog.Event {
 	return Logger.Log()
 }
 
+// Print sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Print.
+func Print(v ...interface{}) {
+	Logger.Print(v...)
+}
+
+// Printf sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Printf.
+func Printf(format string, v ...interface{}) {
+	Logger.Printf(format, v...)
+}
+
 // Ctx returns the Logger associated with the ctx. If no logger
 // is associated, a disabled logger is returned.
-func Ctx(ctx context.Context) zerolog.Logger {
+func Ctx(ctx context.Context) *zerolog.Logger {
 	return zerolog.Ctx(ctx)
 }

vendor/github.com/rs/zerolog/sampler.go

@@ -0,0 +1,126 @@
+package zerolog
+
+import (
+	"math/rand"
+	"sync/atomic"
+	"time"
+)
+
+var (
+	// Often samples log every ~ 10 events.
+	Often = RandomSampler(10)
+	// Sometimes samples log every ~ 100 events.
+	Sometimes = RandomSampler(100)
+	// Rarely samples log every ~ 1000 events.
+	Rarely = RandomSampler(1000)
+)
+
+// Sampler defines an interface to a log sampler.
+type Sampler interface {
+	// Sample returns true if the event should be part of the sample, false if
+	// the event should be dropped.
+	Sample(lvl Level) bool
+}
+
+// RandomSampler use a PRNG to randomly sample an event out of N events,
+// regardless of their level.
+type RandomSampler uint32
+
+// Sample implements the Sampler interface.
+func (s RandomSampler) Sample(lvl Level) bool {
+	if s <= 0 {
+		return false
+	}
+	if rand.Intn(int(s)) != 0 {
+		return false
+	}
+	return true
+}
+
+// BasicSampler is a sampler that will send every Nth events, regardless of
+// there level.
+type BasicSampler struct {
+	N       uint32
+	counter uint32
+}
+
+// Sample implements the Sampler interface.
+func (s *BasicSampler) Sample(lvl Level) bool {
+	c := atomic.AddUint32(&s.counter, 1)
+	return c%s.N == 0
+}
+
+// BurstSampler lets Burst events pass per Period then pass the decision to
+// NextSampler. If Sampler is not set, all subsequent events are rejected.
+type BurstSampler struct {
+	// Burst is the maximum number of event per period allowed before calling
+	// NextSampler.
+	Burst uint32
+	// Period defines the burst period. If 0, NextSampler is always called.
+	Period time.Duration
+	// NextSampler is the sampler used after the burst is reached. If nil,
+	// events are always rejected after the burst.
+	NextSampler Sampler
+
+	counter uint32
+	resetAt int64
+}
+
+// Sample implements the Sampler interface.
+func (s *BurstSampler) Sample(lvl Level) bool {
+	if s.Burst > 9 && s.Period > 0 {
+		if s.inc() <= s.Burst {
+			return true
+		}
+	}
+	if s.NextSampler == nil {
+		return false
+	}
+	return s.NextSampler.Sample(lvl)
+}
+
+func (s *BurstSampler) inc() uint32 {
+	now := time.Now().UnixNano()
+	resetAt := atomic.LoadInt64(&s.resetAt)
+	var c uint32
+	if now > resetAt {
+		c = 1
+		atomic.StoreUint32(&s.counter, c)
+		newResetAt := now + s.Period.Nanoseconds()
+		reset := atomic.CompareAndSwapInt64(&s.resetAt, resetAt, newResetAt)
+		if !reset {
+			// Lost the race with another goroutine trying to reset.
+			c = atomic.AddUint32(&s.counter, 1)
+		}
+	} else {
+		c = atomic.AddUint32(&s.counter, 1)
+	}
+	return c
+}
+
+// LevelSampler applies a different sampler for each level.
+type LevelSampler struct {
+	DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
+}
+
+func (s LevelSampler) Sample(lvl Level) bool {
+	switch lvl {
+	case DebugLevel:
+		if s.DebugSampler != nil {
+			return s.DebugSampler.Sample(lvl)
+		}
+	case InfoLevel:
+		if s.InfoSampler != nil {
+			return s.InfoSampler.Sample(lvl)
+		}
+	case WarnLevel:
+		if s.WarnSampler != nil {
+			return s.WarnSampler.Sample(lvl)
+		}
+	case ErrorLevel:
+		if s.ErrorSampler != nil {
+			return s.ErrorSampler.Sample(lvl)
+		}
+	}
+	return true
+}

vendor/vendor.json

@@ -762,10 +762,10 @@
 			"revisionTime": "2017-04-24T20:45:52Z"
 		},
 		{
-			"checksumSHA1": "fGBeb3o1grSXGUNAjwptkBWfch0=",
+			"checksumSHA1": "3Ie7HG2k47G/gwz8prjymTMLEms=",
 			"path": "github.com/rs/zerolog",
-			"revision": "89ff8dbc5f047ae9957523b07e627891079f7967",
-			"revisionTime": "2017-07-27T06:42:12Z"
+			"revision": "9d194eb6f50e8718a6d6f8f1e1f0bf3ddf4065f1",
+			"revisionTime": "2017-09-11T21:52:32Z"
 		},
 		{
 			"checksumSHA1": "AREhk6LKIp2I/4Njd756bqU6JSQ=",
@@ -774,7 +774,7 @@
 			"revisionTime": "2017-07-27T06:42:12Z"
 		},
 		{
-			"checksumSHA1": "kolarHDX6fkauW+1KWx1SFqSF2o=",
+			"checksumSHA1": "VFgakVFNczJTf9gtUeIpkgcFRf0=",
 			"path": "github.com/rs/zerolog/log",
 			"revision": "89ff8dbc5f047ae9957523b07e627891079f7967",
 			"revisionTime": "2017-07-27T06:42:12Z"