Initial version of MQTT sink

sinks/mqttSink.go

@@ -0,0 +1,372 @@
+package sinks
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"sync"
+	"time"
+
+	cclog "github.com/ClusterCockpit/cc-metric-collector/pkg/ccLogger"
+	lp "github.com/ClusterCockpit/cc-metric-collector/pkg/ccMetric"
+	"github.com/go-mqtt/mqtt"
+	influx "github.com/influxdata/line-protocol/v2/lineprotocol"
+	"golang.org/x/exp/slices"
+)
+
+type MqttSinkConfig struct {
+	// defines JSON tags for 'type' and 'meta_as_tags' (string list)
+	// See: metricSink.go
+	defaultSinkConfig
+	// Additional config options, for MqttSink
+	ClientID             string `json:"client_id"`
+	PersistenceDirectory string `json:"persistence_directory,omitempty"`
+	// Maximum number of points sent to server in single request.
+	// Default: 1000
+	BatchSize int `json:"batch_size,omitempty"`
+
+	// Time interval for delayed sending of metrics.
+	// If the buffers are already filled before the end of this interval,
+	// the metrics are sent without further delay.
+	// Default: 1s
+	FlushInterval string `json:"flush_delay,omitempty"`
+	flushDelay    time.Duration
+
+	DialProtocol string `json:"dial_protocol"`
+	Hostname     string `json:"hostname"`
+	Port         int    `json:"port"`
+	PauseTimeout string `json:"pause_timeout"`
+	pauseTimeout time.Duration
+	KeepAlive    uint16 `json:"keep_alive_seconds"`
+	Username     string `json:"username,omitempty"`
+	Password     string `json:"password,omitempty"`
+}
+
+type MqttSink struct {
+	// declares elements 	'name' and 'meta_as_tags' (string to bool map!)
+	sink
+	config MqttSinkConfig // entry point to the MqttSinkConfig
+	// influx line protocol encoder
+	encoder influx.Encoder
+	// number of records stored in the encoder
+	numRecordsInEncoder int
+	// List of tags and meta data tags which should be used as tags
+	extended_tag_list []key_value_pair
+	// Flush() runs in another goroutine and accesses the influx line protocol encoder,
+	// so this encoderLock has to protect the encoder and numRecordsInEncoder
+	encoderLock sync.Mutex
+
+	// timer to run Flush()
+	flushTimer *time.Timer
+	// Lock to assure that only one timer is running at a time
+	timerLock sync.Mutex
+
+	// WaitGroup to ensure only one send operation is running at a time
+	sendWaitGroup sync.WaitGroup
+
+	client     *mqtt.Client
+	mqttconfig mqtt.Config
+}
+
+// Implement functions required for Sink interface
+// Write(...), Flush(), Close()
+// See: metricSink.go
+
+// Code to submit a single CCMetric to the sink
+func (s *MqttSink) Write(m lp.CCMetric) error {
+
+	// Lock for encoder usage
+	s.encoderLock.Lock()
+
+	// Encode measurement name
+	s.encoder.StartLine(m.Name())
+
+	// copy tags and meta data which should be used as tags
+	s.extended_tag_list = s.extended_tag_list[:0]
+	for key, value := range m.Tags() {
+		s.extended_tag_list =
+			append(
+				s.extended_tag_list,
+				key_value_pair{
+					key:   key,
+					value: value,
+				},
+			)
+	}
+	for _, key := range s.config.MetaAsTags {
+		if value, ok := m.GetMeta(key); ok {
+			s.extended_tag_list =
+				append(
+					s.extended_tag_list,
+					key_value_pair{
+						key:   key,
+						value: value,
+					},
+				)
+		}
+	}
+
+	// Encode tags (they musts be in lexical order)
+	slices.SortFunc(
+		s.extended_tag_list,
+		func(a key_value_pair, b key_value_pair) int {
+			if a.key < b.key {
+				return -1
+			}
+			if a.key > b.key {
+				return +1
+			}
+			return 0
+		},
+	)
+	for i := range s.extended_tag_list {
+		s.encoder.AddTag(
+			s.extended_tag_list[i].key,
+			s.extended_tag_list[i].value,
+		)
+	}
+
+	// Encode fields
+	for key, value := range m.Fields() {
+		s.encoder.AddField(key, influx.MustNewValue(value))
+	}
+
+	// Encode time stamp
+	s.encoder.EndLine(m.Time())
+
+	// Check for encoder errors
+	if err := s.encoder.Err(); err != nil {
+		// Unlock encoder usage
+		s.encoderLock.Unlock()
+
+		return fmt.Errorf("encoding failed: %v", err)
+	}
+	s.numRecordsInEncoder++
+
+	if s.config.flushDelay == 0 {
+		// Unlock encoder usage
+		s.encoderLock.Unlock()
+
+		// Directly flush if no flush delay is configured
+		return s.Flush()
+	} else if s.numRecordsInEncoder == s.config.BatchSize {
+		// Unlock encoder usage
+		s.encoderLock.Unlock()
+
+		// Stop flush timer
+		if s.flushTimer != nil {
+			if ok := s.flushTimer.Stop(); ok {
+				cclog.ComponentDebug(s.name, "Write(): Stopped flush timer. Batch size limit reached before flush delay")
+				s.timerLock.Unlock()
+			}
+		}
+
+		// Flush if batch size is reached
+		return s.Flush()
+	} else if s.timerLock.TryLock() {
+
+		// Setup flush timer when flush delay is configured
+		// and no other timer is already running
+		if s.flushTimer != nil {
+
+			// Restarting existing flush timer
+			cclog.ComponentDebug(s.name, "Write(): Restarting flush timer")
+			s.flushTimer.Reset(s.config.flushDelay)
+		} else {
+
+			// Creating and starting flush timer
+			cclog.ComponentDebug(s.name, "Write(): Starting new flush timer")
+			s.flushTimer = time.AfterFunc(
+				s.config.flushDelay,
+				func() {
+					defer s.timerLock.Unlock()
+					cclog.ComponentDebug(s.name, "Starting flush triggered by flush timer")
+					if err := s.Flush(); err != nil {
+						cclog.ComponentError(s.name, "Flush triggered by flush timer: flush failed:", err)
+					}
+				})
+		}
+	}
+
+	// Unlock encoder usage
+	s.encoderLock.Unlock()
+	return nil
+}
+
+// If the sink uses batched sends internally, you can tell to flush its buffers
+func (s *MqttSink) Flush() error {
+
+	// Lock for encoder usage
+	// Own lock for as short as possible: the time it takes to clone the buffer.
+	s.encoderLock.Lock()
+
+	buf := slices.Clone(s.encoder.Bytes())
+	numRecordsInBuf := s.numRecordsInEncoder
+	s.encoder.Reset()
+	s.numRecordsInEncoder = 0
+
+	// Unlock encoder usage
+	s.encoderLock.Unlock()
+
+	if len(buf) == 0 {
+		return nil
+	}
+
+	cclog.ComponentDebug(s.name, "Flush(): Flushing", numRecordsInBuf, "metrics")
+
+	// Asynchron send of encoder metrics
+	s.sendWaitGroup.Add(1)
+	go func() {
+		defer s.sendWaitGroup.Done()
+		//startTime := time.Now()
+		for {
+			exchange, err := s.client.PublishAtLeastOnce(buf, s.config.ClientID)
+			switch {
+			case err == nil:
+				return
+
+			case mqtt.IsDeny(err), errors.Is(err, mqtt.ErrClosed):
+				return
+
+			case errors.Is(err, mqtt.ErrMax):
+				time.Sleep(s.config.pauseTimeout)
+
+			default:
+				time.Sleep(s.config.pauseTimeout)
+				continue
+			}
+
+			for err := range exchange {
+				if errors.Is(err, mqtt.ErrClosed) {
+					return
+				}
+
+			}
+			return
+		}
+	}()
+	return nil
+}
+
+// Close sink: close network connection, close files, close libraries, ...
+func (s *MqttSink) Close() {
+
+	cclog.ComponentDebug(s.name, "CLOSE")
+
+	// Stop existing timer and immediately flush
+	if s.flushTimer != nil {
+		if ok := s.flushTimer.Stop(); ok {
+			s.timerLock.Unlock()
+		}
+	}
+
+	// Flush
+	if err := s.Flush(); err != nil {
+		cclog.ComponentError(s.name, "Close():", "Flush failed:", err)
+	}
+
+	// Wait for send operations to finish
+	s.sendWaitGroup.Wait()
+
+	s.client.Close()
+	s.client = nil
+}
+
+// New function to create a new instance of the sink
+// Initialize the sink by giving it a name and reading in the config JSON
+func NewMqttSink(name string, config json.RawMessage) (Sink, error) {
+	s := new(MqttSink)
+
+	// Set name of sampleSink
+	// The name should be chosen in such a way that different instances of MqttSink can be distinguished
+	s.name = fmt.Sprintf("MqttSink(%s)", name) // Always specify a name here
+
+	// Set defaults in s.config
+	// Allow overwriting these defaults by reading config JSON
+
+	s.config.PauseTimeout = "4s"
+	s.config.pauseTimeout = time.Duration(4) * time.Second
+	s.config.DialProtocol = "tcp"
+	s.config.Hostname = "localhost"
+	s.config.Port = 1883
+
+	// Read in the config JSON
+	if len(config) > 0 {
+		d := json.NewDecoder(bytes.NewReader(config))
+		d.DisallowUnknownFields()
+		if err := d.Decode(&s.config); err != nil {
+			cclog.ComponentError(s.name, "Error reading config:", err.Error())
+			return nil, err
+		}
+	}
+
+	// Create lookup map to use meta infos as tags in the output metric
+	s.meta_as_tags = make(map[string]bool)
+	for _, k := range s.config.MetaAsTags {
+		s.meta_as_tags[k] = true
+	}
+
+	// Check if all required fields in the config are set
+	// E.g. use 'len(s.config.Option) > 0' for string settings
+	if t, err := time.ParseDuration(s.config.PauseTimeout); err == nil {
+		s.config.pauseTimeout = t
+	} else {
+		err := fmt.Errorf("to parse duration for PauseTimeout: %s", s.config.PauseTimeout)
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+	if t, err := time.ParseDuration(s.config.FlushInterval); err == nil {
+		s.config.flushDelay = t
+	} else {
+		err := fmt.Errorf("to parse duration for FlushInterval: %s", s.config.FlushInterval)
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+
+	switch s.config.DialProtocol {
+	case "tcp", "udp":
+	default:
+		err := errors.New("failed to parse dial protocol, allowed: tcp, udp")
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+
+	var persistence mqtt.Persistence
+	if len(s.config.PersistenceDirectory) > 0 {
+		persistence = mqtt.FileSystem(s.config.PersistenceDirectory)
+	} else {
+		tmpdir, err := os.MkdirTemp("", "mqtt")
+		if err == nil {
+			persistence = mqtt.FileSystem(tmpdir)
+		}
+	}
+
+	// Establish connection to the server, library, ...
+	// Check required files exist and lookup path(s) of executable(s)
+
+	dialer := mqtt.NewDialer(s.config.DialProtocol, net.JoinHostPort(s.config.Hostname, fmt.Sprintf("%d", s.config.Port)))
+
+	s.mqttconfig = mqtt.Config{
+		Dialer:       dialer,
+		PauseTimeout: s.config.pauseTimeout,
+		KeepAlive:    uint16(s.config.KeepAlive),
+	}
+	if len(s.config.Username) > 0 {
+		s.mqttconfig.UserName = s.config.Username
+	}
+	if len(s.config.Password) > 0 {
+		s.mqttconfig.Password = []byte(s.config.Password)
+	}
+
+	client, err := mqtt.InitSession(s.config.ClientID, persistence, &s.mqttconfig)
+	if err != nil {
+		return nil, err
+	}
+	s.client = client
+
+	// Return (nil, meaningful error message) in case of errors
+	return s, nil
+}

sinks/mqttSink.md

@@ -0,0 +1,39 @@
+## `mqtt` sink
+
+The `mqtt` sink publishes all metrics into a MQTT network.
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "mqtt",
+    "client_id" : "myid",
+    "persistence_directory": "/tmp",
+    "batch_size": 1000,
+    "flush_delay": "1s",
+    "dial_protocol": "tcp",
+    "host": "dbhost.example.com",
+    "port": 1883,
+    "user": "exampleuser",
+    "password" : "examplepw",
+    "pause_timeout": "1s",
+    "keep_alive_seconds": 10,
+    "meta_as_tags" : [],
+  }
+}
+```
+
+- `type`: makes the sink an `mqtt` sink
+- `client_id`: MQTT clients use a client_id to talk to the broker
+- `persistence_directory`: MQTT stores messages temporarly on disc if the broker is not available. Folder needs to be writable (default: `/tmp`)
+- `pause_timeout`: Waittime when published failed
+- `keep_alive_seconds`: Keep the connection alive for some time. Recommended to be longer than global `interval`.
+- `flush_delay`: Group metrics coming in to a single batch
+- `batch_size`: Maximal batch size. If `batch_size` is reached before the end of `flush_delay`, the metrics are sent without further delay
+- `dial_protocol`: Use `tcp` or `udp` for the MQTT communication
+- `host`: Hostname of the MQTT broker
+- `port`: Port number of the MQTT broker
+- `user`: Username for authentication
+- `password`: Password for authentication
+- `meta_as_tags`: print all meta information as tags in the output (optional)

sinks/sinkManager.go

@@ -21,6 +21,7 @@ var AvailableSinks = map[string]func(name string, config json.RawMessage) (Sink,
 	"influxdb":    NewInfluxSink,
 	"influxasync": NewInfluxAsyncSink,
 	"http":        NewHttpSink,
+	"mqtt":        NewMqttSink,
 }
 
 // Metric collector manager data structure