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service.go
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service.go
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package patron
import (
"context"
"errors"
"fmt"
"log/slog"
"os"
"os/signal"
"strconv"
"strings"
"sync"
"syscall"
"github.com/beatlabs/patron/log"
"github.com/beatlabs/patron/trace"
"github.com/uber/jaeger-client-go"
)
const (
srv = "srv"
ver = "ver"
host = "host"
)
// Component interface for implementing Service components.
type Component interface {
Run(ctx context.Context) error
}
// Service is responsible for managing and setting up everything.
// The Service will start by default an HTTP component in order to host management endpoint.
type Service struct {
name string
version string
termSig chan os.Signal
sighupHandler func()
logConfig logConfig
}
func New(name, version string, options ...OptionFunc) (*Service, error) {
if name == "" {
return nil, errors.New("name is required")
}
if version == "" {
version = "dev"
}
s := &Service{
name: name,
version: version,
termSig: make(chan os.Signal, 1),
sighupHandler: func() {
slog.Debug("sighup received: nothing setup")
},
logConfig: logConfig{
attrs: defaultLogAttrs(name, version),
json: false,
},
}
var err error
err = setupJaegerTracing(name, version)
if err != nil {
return nil, err
}
optionErrors := make([]error, 0)
for _, option := range options {
err = option(s)
if err != nil {
optionErrors = append(optionErrors, err)
}
}
if len(optionErrors) > 0 {
return nil, errors.Join(optionErrors...)
}
setupLogging(s.logConfig)
s.setupOSSignal()
return s, nil
}
func (s *Service) Run(ctx context.Context, components ...Component) error {
if len(components) == 0 || components[0] == nil {
return errors.New("components are empty or nil")
}
defer func() {
err := trace.Close()
if err != nil {
slog.Error("failed to close trace", slog.Any("error", err))
}
}()
ctx, cnl := context.WithCancel(ctx)
chErr := make(chan error, len(components))
wg := sync.WaitGroup{}
wg.Add(len(components))
for _, cp := range components {
go func(c Component) {
defer wg.Done()
chErr <- c.Run(ctx)
}(cp)
}
log.FromContext(ctx).Info("service started", slog.String("name", s.name))
ee := make([]error, 0, len(components))
ee = append(ee, s.waitTermination(chErr))
cnl()
wg.Wait()
close(chErr)
for err := range chErr {
ee = append(ee, err)
}
return errors.Join(ee...)
}
func (s *Service) setupOSSignal() {
signal.Notify(s.termSig, os.Interrupt, syscall.SIGTERM, syscall.SIGHUP)
}
func (s *Service) waitTermination(chErr <-chan error) error {
for {
select {
case sig := <-s.termSig:
slog.Info("signal received", slog.Any("type", sig))
switch sig {
case syscall.SIGHUP:
s.sighupHandler()
return nil
default:
return nil
}
case err := <-chErr:
if err != nil {
slog.Info("component error received")
}
return err
}
}
}
type logConfig struct {
attrs []slog.Attr
json bool
}
func getLogLevel() slog.Level {
lvl, ok := os.LookupEnv("PATRON_LOG_LEVEL")
if !ok {
return slog.LevelInfo
}
lv := slog.LevelVar{}
if err := lv.UnmarshalText([]byte(lvl)); err != nil {
return slog.LevelInfo
}
return lv.Level()
}
func defaultLogAttrs(name, version string) []slog.Attr {
hostname, err := os.Hostname()
if err != nil {
hostname = host
}
return []slog.Attr{
slog.String(srv, name),
slog.String(ver, version),
slog.String(host, hostname),
}
}
func setupLogging(lc logConfig) {
ho := &slog.HandlerOptions{
AddSource: true,
Level: getLogLevel(),
}
var hnd slog.Handler
if lc.json {
hnd = slog.NewJSONHandler(os.Stderr, ho)
} else {
hnd = slog.NewTextHandler(os.Stderr, ho)
}
slog.New(hnd.WithAttrs(lc.attrs))
}
func setupJaegerTracing(name, version string) error {
host, ok := os.LookupEnv("PATRON_JAEGER_AGENT_HOST")
if !ok {
host = "0.0.0.0"
}
port, ok := os.LookupEnv("PATRON_JAEGER_AGENT_PORT")
if !ok {
port = "6831"
}
agent := host + ":" + port
tp, ok := os.LookupEnv("PATRON_JAEGER_SAMPLER_TYPE")
if !ok {
tp = jaeger.SamplerTypeProbabilistic
}
prmVal := 0.0
if prm, ok := os.LookupEnv("PATRON_JAEGER_SAMPLER_PARAM"); ok {
tmpVal, err := strconv.ParseFloat(prm, 64)
if err != nil {
return fmt.Errorf("env var for jaeger sampler param is not valid: %w", err)
}
prmVal = tmpVal
}
var buckets []float64
if b, ok := os.LookupEnv("PATRON_JAEGER_DEFAULT_BUCKETS"); ok {
for _, bs := range strings.Split(b, ",") {
val, err := strconv.ParseFloat(strings.TrimSpace(bs), 64)
if err != nil {
return fmt.Errorf("env var for jaeger default buckets contains invalid value: %w", err)
}
buckets = append(buckets, val)
}
}
slog.Debug("setting up default tracing", slog.String("agent", agent), slog.String("param", tp), slog.Float64("val", prmVal))
return trace.Setup(name, version, agent, tp, prmVal, buckets)
}