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noaalert.go
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noaalert.go
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package noaalert
import (
"context"
"os"
"os/signal"
"time"
sdk "github.com/rotationalio/go-ensign"
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
func init() {
// Initializes zerolog with our default logging requirements
zerolog.TimeFieldFormat = time.RFC3339
zerolog.DurationFieldInteger = false
zerolog.DurationFieldUnit = time.Millisecond
}
type Publisher struct {
api *Weather
ensign *sdk.Client
conf Config
started time.Time
echan chan error
}
func New(conf Config) (pub *Publisher, err error) {
if conf.IsZero() {
if conf, err = NewConfig(); err != nil {
return nil, err
}
}
if conf.ConsoleLog {
log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
}
pub = &Publisher{
conf: conf,
echan: make(chan error, 1),
}
// Connect to Weather.gov
if pub.api, err = NewWeatherAPI(); err != nil {
return nil, err
}
// Connect to Ensign
if pub.ensign, err = sdk.New(conf.Ensign.Options()...); err != nil {
return nil, err
}
// If we need to ensure the topic exists, perform the check.
if conf.EnsureTopicExists {
if err = EnsureTopicExists(pub.ensign, conf.Topic); err != nil {
return nil, err
}
}
return pub, nil
}
func (p *Publisher) Run() error {
// Catch OS signals for graceful shutdowns
quit := make(chan os.Signal, 1)
signal.Notify(quit, os.Interrupt)
go func() {
<-quit
p.echan <- p.Shutdown()
}()
p.started = time.Now()
ticker := time.NewTicker(p.conf.Interval)
log.Info().Dur("interval", p.conf.Interval).Str("topic", p.conf.Topic).Msg("starting alerts publisher")
// Begin API query loop
queryLoop:
for {
select {
case err := <-p.echan:
return err
case <-ticker.C:
log.Debug().Msg("starting collection of noaa alerts")
count := 0
for alert := range p.Alerts() {
if err := p.ensign.Publish(p.conf.Topic, alert); err != nil {
log.Error().Err(err).Int("count", count).Msg("could not publish weather alert")
continue queryLoop
}
// TODO: check acks/nacks
count++
}
log.Info().Str("topic", p.conf.Topic).Int("count", count).Msg("weather alerts published")
}
}
}
func (p *Publisher) Shutdown() (err error) {
log.Info().Msg("shutting alert publisher down")
if err = p.ensign.Close(); err != nil {
return err
}
log.Debug().Msg("gracefully shut down alert publisher")
return nil
}
func (p *Publisher) Alerts() <-chan *sdk.Event {
events := make(chan *sdk.Event)
go func(events chan<- *sdk.Event) {
defer close(events)
// TODO: set default timeout in configuration
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
alerts, err := p.api.Alerts(ctx)
if err != nil {
log.Warn().Err(err).Msg("could not fetch noaa alerts")
return
}
log.Debug().Int("nalerts", len(alerts)).Msg("received alerts from NOAA")
for _, alert := range alerts {
// TODO: don't republish alerts
events <- alert.Event()
}
}(events)
return events
}