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service.go
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service.go
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package msvc
import (
"context"
"fmt"
"github.com/arikkfir/msvc/util"
kitlog "github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/pkg/errors"
"github.com/spf13/viper"
stdlog "log"
"os"
"os/signal"
"strings"
"sync"
"syscall"
)
const (
EnvDevelopment = iota
EnvProduction
contextMsKey = "__ms"
)
func GetFromContext(ctx context.Context) *MicroService {
value := ctx.Value(contextMsKey)
if value == nil {
return nil
} else {
return value.(*MicroService)
}
}
func SetInContext(ctx context.Context, ms *MicroService) context.Context {
return context.WithValue(ctx, contextMsKey, ms)
}
type Method func(ctx context.Context, request interface{}) (interface{}, error)
type Middleware func(ms *MicroService, methodName string, method Method) Method
type Daemon func() error
type MicroService struct {
config interface{}
environment int
log kitlog.Logger
methods map[string]MethodAdapter
daemons []Daemon
middlewares []Middleware
methodChains map[string]Method
name string
}
func New(name string, config interface{}) (*MicroService, error) {
prefix := strings.ToUpper(name)
// Determine the environment
environment := EnvDevelopment
envName := "dev"
switch env := os.Getenv(prefix + "_ENV"); strings.ToLower(env) {
case "prod", "production", "prd":
environment = EnvProduction
envName = "prod"
}
// Log level
// Configure stdout
var logger kitlog.Logger
stdoutWriter := kitlog.NewSyncWriter(os.Stdout)
if environment == EnvDevelopment {
logger = kitlog.NewLogfmtLogger(stdoutWriter)
} else {
logger = kitlog.NewJSONLogger(stdoutWriter)
}
logger = kitlog.With(logger, "svc", name)
logger = kitlog.With(logger, "env", envName)
logger = kitlog.With(logger, "ts", kitlog.DefaultTimestamp)
switch logLevel := os.Getenv(prefix + "_LOGLEVEL"); strings.ToLower(logLevel) {
case "debug":
logger = level.NewFilter(logger, level.AllowDebug())
case "info":
logger = level.NewFilter(logger, level.AllowInfo())
case "warn":
logger = level.NewFilter(logger, level.AllowWarn())
case "error":
logger = level.NewFilter(logger, level.AllowError())
default:
logger = level.NewFilter(logger, level.AllowAll())
}
logger = util.CreateStackTraceLoggerFunc(stdoutWriter, logger)
stdlog.SetOutput(kitlog.NewStdlibAdapter(logger))
// Load application configuration
v := viper.New()
v.SetConfigName(name)
v.AddConfigPath(".")
v.AddConfigPath(fmt.Sprintf("/etc/%s/", name))
v.AutomaticEnv()
v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
v.SetEnvPrefix(prefix)
if err := v.Unmarshal(config); err != nil {
return nil, errors.Wrap(err, "failed reading configuration")
}
// Create the service
return &MicroService{
config: config,
environment: environment,
log: logger,
name: name,
daemons: make([]Daemon, 0),
middlewares: make([]Middleware, 0),
methods: make(map[string]MethodAdapter, 0),
methodChains: make(map[string]Method, 0),
}, nil
}
func (ms *MicroService) Config() interface{} {
return ms.config
}
func (ms *MicroService) Environment() int {
return ms.environment
}
func (ms *MicroService) Log(kv ...interface{}) {
_ = ms.log.Log(kv...)
}
func (ms *MicroService) Name() string {
return ms.name
}
func (ms *MicroService) AddMethod(name string, method interface{}) MethodAdapter {
adapter := NewAdapter(method)
ms.methods[name] = adapter
ms.compileMethodChains()
return adapter
}
func (ms *MicroService) GetMethod(name string) Method {
return ms.methodChains[name]
}
func (ms *MicroService) GetMethodAdapter(name string) MethodAdapter {
return ms.methods[name]
}
func (ms *MicroService) RemoveMethod(name string) {
delete(ms.methods, name)
ms.compileMethodChains()
}
func (ms *MicroService) AddMiddleware(middleware Middleware) {
ms.middlewares = append(ms.middlewares, middleware)
ms.compileMethodChains()
}
func (ms *MicroService) AddDaemon(daemon Daemon) {
ms.daemons = append(ms.daemons, daemon)
}
func (ms *MicroService) compileMethodChains() {
methodChains := map[string]Method{}
for name, methodAdapter := range ms.methods {
currentMethod := methodAdapter.Call
for _, mw := range ms.middlewares {
currentMethod = mw(ms, name, currentMethod)
}
methodChains[name] = currentMethod
}
ms.methodChains = methodChains
}
func (ms *MicroService) Run() {
// Start each daemon in a goroutine; if a daemon fails, it will send the error to the errors channel (termination)
daemonsWaitGroup := sync.WaitGroup{}
daemonsWaitGroup.Add(len(ms.daemons))
errChan := make(chan error, 1)
doneChan := make(chan bool, 1)
for _, d := range ms.daemons {
daemon := d
go func() {
if err := daemon(); err != nil {
errChan <- errors.Wrapf(err, "daemon failed")
} else {
daemonsWaitGroup.Done()
}
}()
}
// Start a goroutine which will wait until all daemons exit successfully, and if so notify the "done" channel
go func() {
daemonsWaitGroup.Wait()
doneChan <- true
}()
// Listen for OS signals SIGINT and SIGTERM
signalsChan := make(chan os.Signal, 1)
signal.Notify(signalsChan, syscall.SIGINT, syscall.SIGTERM)
//
// Wait until we get an error or a signal, print it and exit
select {
case err := <-errChan:
ms.Log("err", err)
os.Exit(1)
case sig := <-signalsChan:
ms.Log("msg", "received signal '"+sig.String()+"'")
os.Exit(1)
case <-doneChan:
ms.Log("msg", "done")
os.Exit(0)
}
}