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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 (
"context"
"fmt"
"log"
"net/http"
"os"
"strconv"
"strings"
"time"
kitprometheus "github.com/go-kit/kit/metrics/prometheus"
"github.com/gocql/gocql"
"github.com/mainflux/mainflux"
"github.com/mainflux/mainflux/consumers"
"github.com/mainflux/mainflux/consumers/writers/api"
"github.com/mainflux/mainflux/consumers/writers/cassandra"
"github.com/mainflux/mainflux/logger"
"github.com/mainflux/mainflux/pkg/errors"
"github.com/mainflux/mainflux/pkg/messaging/nats"
stdprometheus "github.com/prometheus/client_golang/prometheus"
"golang.org/x/sync/errgroup"
)
const (
svcName = "cassandra-writer"
sep = ","
stopWaitTime = 5 * time.Second
defNatsURL = "nats://localhost:4222"
defLogLevel = "error"
defPort = "8180"
defCluster = "127.0.0.1"
defKeyspace = "mainflux"
defDBUser = "mainflux"
defDBPass = "mainflux"
defDBPort = "9042"
defConfigPath = "/config.toml"
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"
envConfigPath = "MF_CASSANDRA_WRITER_CONFIG_PATH"
)
type config struct {
natsURL string
logLevel string
port string
configPath string
dbCfg cassandra.DBConfig
}
func main() {
cfg := loadConfig()
ctx, cancel := context.WithCancel(context.Background())
g, ctx := errgroup.WithContext(ctx)
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)
if err := consumers.Start(svcName, pubSub, repo, cfg.configPath, logger); err != nil {
logger.Error(fmt.Sprintf("Failed to create Cassandra writer: %s", err))
}
go startHTTPServer(ctx, cfg.port, logger)
g.Go(func() error {
if sig := errors.SignalHandler(ctx); sig != nil {
cancel()
logger.Info(fmt.Sprintf("Cassandra writer service shutdown by signal: %s", sig))
}
return nil
})
if err := g.Wait(); err != nil {
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),
configPath: mainflux.Env(envConfigPath, defConfigPath),
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) consumers.Consumer {
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(ctx context.Context, port string, logger logger.Logger) error {
p := fmt.Sprintf(":%s", port)
errCh := make(chan error)
server := &http.Server{Addr: p, Handler: api.MakeHandler(svcName)}
logger.Info(fmt.Sprintf("Cassandra writer service started, exposed port %s", port))
go func() {
errCh <- server.ListenAndServe()
}()
select {
case <-ctx.Done():
ctxShutdown, cancelShutdown := context.WithTimeout(context.Background(), stopWaitTime)
defer cancelShutdown()
if err := server.Shutdown(ctxShutdown); err != nil {
logger.Error(fmt.Sprintf("Cassandra writer service error occurred during shutdown at %s: %s", p, err))
return fmt.Errorf("cassandra writer service error occurred during shutdown at %s: %w", p, err)
}
logger.Info(fmt.Sprintf("Cassandra writer service shutdown of http at %s", p))
return nil
case err := <-errCh:
return err
}
}