Implement LOG_FORMAT=json

README.md

@@ -19,6 +19,7 @@
       - [Example 3](#example-3)
       - [Example 4](#example-4)
   - [Loading Configuration](#loading-configuration)
+  - [Log Format](#log-format)
 - [Request Fields](#request-fields)
 - [Statistics](#statistics)
 - [HTTP Port](#http-port)
@@ -347,6 +348,40 @@ The former is the default behavior. To use the latter method, set the `RUNTIME_W
 
 For more information on how runtime works you can read its [README](https://github.com/lyft/goruntime).
 
+## Log Format
+
+A centralized log collection system works better with logs in json format. JSON format avoids the need for custom parsing rules.
+The Ratelimit service produces logs in a text format by default. For Example:
+
+```
+time="2020-09-10T17:22:35Z" level=debug msg="loading domain: messaging"
+time="2020-09-10T17:22:35Z" level=debug msg="loading descriptor: key=messaging.message_type_marketing"
+time="2020-09-10T17:22:35Z" level=debug msg="loading descriptor: key=messaging.message_type_marketing.to_number ratelimit={requests_per_unit=5, unit=DAY}"
+time="2020-09-10T17:22:35Z" level=debug msg="loading descriptor: key=messaging.to_number ratelimit={requests_per_unit=100, unit=DAY}"
+time="2020-09-10T17:21:55Z" level=warning msg="Listening for debug on ':6070'"
+time="2020-09-10T17:21:55Z" level=warning msg="Listening for HTTP on ':8080'"
+time="2020-09-10T17:21:55Z" level=debug msg="waiting for runtime update"
+time="2020-09-10T17:21:55Z" level=warning msg="Listening for gRPC on ':8081'"
+```
+
+JSON Log format can be configured using the following environment variables:
+
+```
+LOG_FORMAT=json
+```
+
+Output example:
+```
+{"@message":"loading domain: messaging","@timestamp":"2020-09-10T17:22:44.926010192Z","level":"debug"}
+{"@message":"loading descriptor: key=messaging.message_type_marketing","@timestamp":"2020-09-10T17:22:44.926019315Z","level":"debug"}
+{"@message":"loading descriptor: key=messaging.message_type_marketing.to_number ratelimit={requests_per_unit=5, unit=DAY}","@timestamp":"2020-09-10T17:22:44.926037174Z","level":"debug"}
+{"@message":"loading descriptor: key=messaging.to_number ratelimit={requests_per_unit=100, unit=DAY}","@timestamp":"2020-09-10T17:22:44.926048993Z","level":"debug"}
+{"@message":"Listening for debug on ':6070'","@timestamp":"2020-09-10T17:22:44.926113905Z","level":"warning"}
+{"@message":"Listening for gRPC on ':8081'","@timestamp":"2020-09-10T17:22:44.926182006Z","level":"warning"}
+{"@message":"Listening for HTTP on ':8080'","@timestamp":"2020-09-10T17:22:44.926227031Z","level":"warning"}
+{"@message":"waiting for runtime update","@timestamp":"2020-09-10T17:22:44.926267808Z","level":"debug"}
+```
+
 # Request Fields
 
 For information on the fields of a Ratelimit gRPC request please read the information

src/service_cmd/runner/runner.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"math/rand"
 	"net/http"
+	"strings"
 	"time"
 
 	stats "github.com/lyft/gostats"
@@ -43,6 +44,16 @@ func (runner *Runner) Run() {
 	} else {
 		logger.SetLevel(logLevel)
 	}
+	if strings.ToLower(s.LogFormat) == "json" {
+		logger.SetFormatter(&logger.JSONFormatter{
+			TimestampFormat: time.RFC3339Nano,
+			FieldMap: logger.FieldMap{
+				logger.FieldKeyTime: "@timestamp",
+				logger.FieldKeyMsg:  "@message",
+			},
+		})
+	}
+
 	var localCache *freecache.Cache
 	if s.LocalCacheSizeInBytes != 0 {
 		localCache = freecache.NewCache(s.LocalCacheSizeInBytes)

src/settings/settings.go

@@ -22,6 +22,7 @@ type Settings struct {
 	RuntimeIgnoreDotFiles        bool          `envconfig:"RUNTIME_IGNOREDOTFILES" default:"false"`
 	RuntimeWatchRoot             bool          `envconfig:"RUNTIME_WATCH_ROOT" default:"true"`
 	LogLevel                     string        `envconfig:"LOG_LEVEL" default:"WARN"`
+	LogFormat                    string        `envconfig:"LOG_FORMAT" default:"text"`
 	RedisSocketType              string        `envconfig:"REDIS_SOCKET_TYPE" default:"unix"`
 	RedisUrl                     string        `envconfig:"REDIS_URL" default:"/var/run/nutcracker/ratelimit.sock"`
 	RedisPoolSize                int           `envconfig:"REDIS_POOL_SIZE" default:"10"`