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main.go
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main.go
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// Copyright (c) Mainflux
// SPDX-License-Identifier: Apache-2.0
package main
import (
"fmt"
"log"
"net/http"
"os"
"os/signal"
"strconv"
"strings"
"syscall"
kitprometheus "github.com/go-kit/kit/metrics/prometheus"
"github.com/gocql/gocql"
"github.com/mainflux/mainflux"
"github.com/mainflux/mainflux/logger"
"github.com/mainflux/mainflux/pkg/messaging/nats"
"github.com/mainflux/mainflux/pkg/transformers/senml"
"github.com/mainflux/mainflux/writers"
"github.com/mainflux/mainflux/writers/api"
"github.com/mainflux/mainflux/writers/cassandra"
stdprometheus "github.com/prometheus/client_golang/prometheus"
)
const (
svcName = "cassandra-writer"
sep = ","
defNatsURL = "nats://localhost:4222"
defLogLevel = "error"
defPort = "8180"
defCluster = "127.0.0.1"
defKeyspace = "messages"
defDBUser = "mainflux"
defDBPass = "mainflux"
defDBPort = "9042"
defSubjectsCfgPath = "/config/subjects.toml"
defContentType = "application/senml+json"
envNatsURL = "MF_NATS_URL"
envLogLevel = "MF_CASSANDRA_WRITER_LOG_LEVEL"
envPort = "MF_CASSANDRA_WRITER_PORT"
envCluster = "MF_CASSANDRA_WRITER_DB_CLUSTER"
envKeyspace = "MF_CASSANDRA_WRITER_DB_KEYSPACE"
envDBUser = "MF_CASSANDRA_WRITER_DB_USER"
envDBPass = "MF_CASSANDRA_WRITER_DB_PASS"
envDBPort = "MF_CASSANDRA_WRITER_DB_PORT"
envSubjectsCfgPath = "MF_CASSANDRA_WRITER_SUBJECTS_CONFIG"
envContentType = "MF_CASSANDRA_WRITER_CONTENT_TYPE"
)
type config struct {
natsURL string
logLevel string
port string
subjectsCfgPath string
contentType string
dbCfg cassandra.DBConfig
}
func main() {
cfg := loadConfig()
logger, err := logger.New(os.Stdout, cfg.logLevel)
if err != nil {
log.Fatalf(err.Error())
}
pubSub, err := nats.NewPubSub(cfg.natsURL, "", logger)
if err != nil {
logger.Error(fmt.Sprintf("Failed to connect to NATS: %s", err))
os.Exit(1)
}
defer pubSub.Close()
session := connectToCassandra(cfg.dbCfg, logger)
defer session.Close()
repo := newService(session, logger)
st := senml.New(cfg.contentType)
if err := writers.Start(pubSub, repo, st, svcName, cfg.subjectsCfgPath, logger); err != nil {
logger.Error(fmt.Sprintf("Failed to create Cassandra writer: %s", err))
}
errs := make(chan error, 2)
go startHTTPServer(cfg.port, errs, logger)
go func() {
c := make(chan os.Signal)
signal.Notify(c, syscall.SIGINT)
errs <- fmt.Errorf("%s", <-c)
}()
err = <-errs
logger.Error(fmt.Sprintf("Cassandra writer service terminated: %s", err))
}
func loadConfig() config {
dbPort, err := strconv.Atoi(mainflux.Env(envDBPort, defDBPort))
if err != nil {
log.Fatal(err)
}
dbCfg := cassandra.DBConfig{
Hosts: strings.Split(mainflux.Env(envCluster, defCluster), sep),
Keyspace: mainflux.Env(envKeyspace, defKeyspace),
User: mainflux.Env(envDBUser, defDBUser),
Pass: mainflux.Env(envDBPass, defDBPass),
Port: dbPort,
}
return config{
natsURL: mainflux.Env(envNatsURL, defNatsURL),
logLevel: mainflux.Env(envLogLevel, defLogLevel),
port: mainflux.Env(envPort, defPort),
subjectsCfgPath: mainflux.Env(envSubjectsCfgPath, defSubjectsCfgPath),
contentType: mainflux.Env(envContentType, defContentType),
dbCfg: dbCfg,
}
}
func connectToCassandra(dbCfg cassandra.DBConfig, logger logger.Logger) *gocql.Session {
session, err := cassandra.Connect(dbCfg)
if err != nil {
logger.Error(fmt.Sprintf("Failed to connect to Cassandra cluster: %s", err))
os.Exit(1)
}
return session
}
func newService(session *gocql.Session, logger logger.Logger) writers.MessageRepository {
repo := cassandra.New(session)
repo = api.LoggingMiddleware(repo, logger)
repo = api.MetricsMiddleware(
repo,
kitprometheus.NewCounterFrom(stdprometheus.CounterOpts{
Namespace: "cassandra",
Subsystem: "message_writer",
Name: "request_count",
Help: "Number of requests received.",
}, []string{"method"}),
kitprometheus.NewSummaryFrom(stdprometheus.SummaryOpts{
Namespace: "cassandra",
Subsystem: "message_writer",
Name: "request_latency_microseconds",
Help: "Total duration of requests in microseconds.",
}, []string{"method"}),
)
return repo
}
func startHTTPServer(port string, errs chan error, logger logger.Logger) {
p := fmt.Sprintf(":%s", port)
logger.Info(fmt.Sprintf("Cassandra writer service started, exposed port %s", port))
errs <- http.ListenAndServe(p, api.MakeHandler(svcName))
}