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kafka.go
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kafka.go
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package kafka
import (
"encoding/json"
"errors"
"fmt"
"log"
"os"
"strconv"
"strings"
"time"
"github.com/gliderlabs/logspout/router"
"gopkg.in/Shopify/sarama.v1"
)
const (
NO_MESSAGE_PROVIDED = "no message"
LOGTYPE_APPLICATIONLOG = "applog"
LOGTYPE_ACCESSLOG = "accesslog"
)
func init() {
router.AdapterFactories.Register(NewKafkaAdapter, "kafka")
}
type KafkaAdapter struct {
route *router.Route
brokers []string
topic string
producer sarama.AsyncProducer
docker_host string
use_v0 bool
logstash_type string
dedot_labels bool
msg_counter int
}
type DockerFields struct {
Name string `json:"name"`
CID string `json:"cid"`
Image string `json:"image"`
ImageTag string `json:"image_tag,omitempty"`
Source string `json:"source"`
DockerHost string `json:"docker_host,omitempty"`
Labels map[string]string `json:"labels,omitempty"`
}
type LogstashFields struct {
Docker DockerFields `json:"docker"`
}
type LogstashMessageV0 struct {
Type string `json:"@type,omitempty"`
Timestamp string `json:"@timestamp"`
Sourcehost string `json:"@source_host"`
Message string `json:"@message"`
Fields LogstashFields `json:"@fields"`
}
type LogstashMessageV1 struct {
Type string `json:"@type,omitempty"`
Timestamp string `json:"@timestamp"`
Sourcehost string `json:"host"`
Message string `json:"message"`
Fields DockerFields `json:"docker"`
Logtype string `json:"logtype,omitempty"`
// Only one of the following 3 is initialized and used, depending on the incoming json:logtype
LogtypeAccessfields map[string]interface{} `json:"accesslog,omitempty"`
LogtypeAppfields map[string]interface{} `json:"applog,omitempty"`
LogtypeEventfields map[string]interface{} `json:"event,omitempty"`
}
func NewKafkaAdapter(route *router.Route) (router.LogAdapter, error) {
brokers := readBrokers(route.Address)
if len(brokers) == 0 {
return nil, errorf("The Kafka broker host:port is missing. Did you specify it as a route address?")
}
topic := readTopic(route.Address, route.Options)
if topic == "" {
return nil, errorf("The Kafka topic is missing. Did you specify it as a route option?")
}
var err error
if os.Getenv("DEBUG") != "" {
log.Printf("Starting Kafka producer for address: %s, topic: %s.\n", brokers, topic)
}
var retries int
retries, err = strconv.Atoi(os.Getenv("KAFKA_CONNECT_RETRIES"))
if err != nil {
retries = 3
}
var producer sarama.AsyncProducer
for i := 0; i < retries; i++ {
producer, err = sarama.NewAsyncProducer(brokers, newConfig())
if err != nil {
if os.Getenv("DEBUG") != "" {
log.Println("Couldn't create Kafka producer. Retrying...", err)
}
if i == retries-1 {
return nil, errorf("Couldn't create Kafka producer. %v", err)
}
} else {
time.Sleep(1 * time.Second)
}
}
dedot_labels := getopt(route.Options, "dedot_labels", "DEDOT_LABELS", "false") == "true"
return &KafkaAdapter{
route: route,
brokers: brokers,
topic: topic,
producer: producer,
dedot_labels: dedot_labels,
}, nil
}
func (a *KafkaAdapter) Stream(logstream chan *router.Message) {
defer a.producer.Close()
for rm := range logstream {
a.msg_counter += 1
message, err := createLogstashMessage(rm, a.topic, a.docker_host, a.use_v0, a.logstash_type, a.dedot_labels)
if err != nil {
log.Println("kafka:", err)
a.route.Close()
break
}
a.producer.Input() <- message
}
}
func newConfig() *sarama.Config {
config := sarama.NewConfig()
config.ClientID = "logspout"
config.Producer.Return.Errors = false
config.Producer.Return.Successes = false
config.Producer.Flush.Frequency = 1 * time.Second
config.Producer.RequiredAcks = sarama.WaitForLocal
if opt := os.Getenv("KAFKA_COMPRESSION_CODEC"); opt != "" {
switch opt {
case "gzip":
config.Producer.Compression = sarama.CompressionGZIP
case "snappy":
config.Producer.Compression = sarama.CompressionSnappy
}
}
return config
}
func splitImage(image_tag string) (image string, tag string) {
colon := strings.LastIndex(image_tag, ":")
sep := strings.LastIndex(image_tag, "/")
if colon > -1 && sep < colon {
image = image_tag[0:colon]
tag = image_tag[colon+1:]
} else {
image = image_tag
}
return
}
func dedotLabels(labels map[string]string) map[string]string {
for key, _ := range labels {
if strings.Contains(key, ".") {
dedotted_label := strings.Replace(key, ".", "_", -1)
labels[dedotted_label] = labels[key]
delete(labels, key)
}
}
return labels
}
func validJsonMessage(s string) bool {
if !strings.HasPrefix(s, "{") || !strings.HasSuffix(s, "}") {
return false
}
return true
}
func createLogstashMessage(m *router.Message, topic string, docker_host string, use_v0 bool, logstash_type string, dedot_labels bool) (*sarama.ProducerMessage, error) {
image, image_tag := splitImage(m.Container.Config.Image)
cid := m.Container.ID[0:12]
name := m.Container.Name[1:]
timestamp := m.Time.UTC().Format(time.RFC3339Nano)
msg := LogstashMessageV1{}
msg.Type = logstash_type
msg.Timestamp = timestamp
msg.Sourcehost = m.Container.Config.Hostname
msg.Fields.CID = cid
msg.Fields.Name = name
msg.Fields.Image = image
msg.Fields.ImageTag = image_tag
msg.Fields.Source = m.Source
msg.Fields.DockerHost = docker_host
// see https://github.com/rtoma/logspout-redis-logstash/issues/11
if dedot_labels {
msg.Fields.Labels = dedotLabels(m.Container.Config.Labels)
} else {
msg.Fields.Labels = m.Container.Config.Labels
}
// Check if the message to log itself is json
if validJsonMessage(strings.TrimSpace(m.Data)) {
// So it is, include it in the LogstashmessageV1
err := msg.UnmarshalDynamicJSON([]byte(m.Data))
if err != nil {
// Can't unmarshall the json (invalid?), put it in message
msg.Message = m.Data
} else if msg.Message == "" {
msg.Message = NO_MESSAGE_PROVIDED
}
} else {
// Regular logging (no json)
msg.Message = m.Data
}
var encoder sarama.Encoder
jsonMessage,_ := json.Marshal(msg)
encoder = sarama.ByteEncoder(jsonMessage)
return &sarama.ProducerMessage{
Topic: topic,
Value: encoder,
}, nil
}
func (d *LogstashMessageV1) UnmarshalDynamicJSON(data []byte) error {
var dynMap map[string]interface{}
if d == nil {
return errors.New("RawString: UnmarshalJSON on nil pointer")
}
if err := json.Unmarshal(data, &dynMap); err != nil {
return err
}
// Take logtype of the hash, but only if it is a valid logtype
if _, ok := dynMap["logtype"].(string); ok {
if dynMap["logtype"].(string) == LOGTYPE_APPLICATIONLOG || dynMap["logtype"].(string) == LOGTYPE_ACCESSLOG {
d.Logtype = dynMap["logtype"].(string)
delete(dynMap, "logtype")
}
}
// Take message out of the hash
if _, ok := dynMap["message"]; ok {
d.Message = dynMap["message"].(string)
delete(dynMap, "message")
}
// Only initialize the "used" hash in struct
if d.Logtype == LOGTYPE_APPLICATIONLOG {
d.LogtypeAppfields = make(map[string]interface{}, 0)
} else if d.Logtype == LOGTYPE_ACCESSLOG {
d.LogtypeAccessfields = make(map[string]interface{}, 0)
} else {
d.LogtypeEventfields = make(map[string]interface{}, 0)
}
// Fill the right hash based on logtype
for key, val := range dynMap {
if d.Logtype == LOGTYPE_APPLICATIONLOG {
d.LogtypeAppfields[key] = val
} else if d.Logtype == LOGTYPE_ACCESSLOG {
d.LogtypeAccessfields[key] = val
} else {
d.LogtypeEventfields[key] = val
}
}
return nil
}
func readBrokers(address string) []string {
if strings.Contains(address, "/") {
slash := strings.Index(address, "/")
address = address[:slash]
}
return strings.Split(address, ",")
}
func readTopic(address string, options map[string]string) string {
var topic string
if !strings.Contains(address, "/") {
topic = options["topic"]
} else {
slash := strings.Index(address, "/")
topic = address[slash+1:]
}
return topic
}
func errorf(format string, a ...interface{}) (err error) {
err = fmt.Errorf(format, a...)
if os.Getenv("DEBUG") != "" {
fmt.Println(err.Error())
}
return
}
func getopt(options map[string]string, optkey string, envkey string, default_value string) (value string) {
value = options[optkey]
if value == "" {
value = os.Getenv(envkey)
if value == "" {
value = default_value
}
}
return
}