/
main.go
121 lines (94 loc) · 2.5 KB
/
main.go
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// Main package.
// --8<-- [start:pkg-main]
package main
// --8<-- [end:pkg-main]
import (
"context"
"flag"
"fmt"
"io"
"os"
"os/signal"
"syscall"
syslog "github.com/RackSec/srslog"
"github.com/rs/zerolog"
"github.com/srl-labs/ndk-greeter-go/greeter"
"google.golang.org/grpc/metadata"
"gopkg.in/natefinch/lumberjack.v2"
)
// --8<-- [start:pkg-main-vars].
var (
version = "0.0.0"
commit = ""
)
// --8<-- [end:pkg-main-vars]
// Main entry point for the application.
// --8<-- [start:main].
func main() {
versionFlag := flag.Bool("version", false, "print the version and exit")
flag.Parse()
if *versionFlag {
fmt.Println(version + "-" + commit)
os.Exit(0)
}
logger := setupLogger()
// --8<-- [start:metadata]
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ctx = metadata.AppendToOutgoingContext(ctx, "agent_name", greeter.AppName)
// --8<-- [end:metadata]
exitHandler(cancel)
// --8<-- [start:main-init-app]
app := greeter.NewApp(ctx, &logger)
app.Start(ctx)
// --8<-- [end:main-init-app]
}
// --8<-- [end:main]
// ExitHandler cancels the main context when interrupt or term signals are sent.
// --8<-- [start:exit-handler].
func exitHandler(cancel context.CancelFunc) {
// handle CTRL-C signal
sig := make(chan os.Signal, 1)
signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
go func() {
<-sig
cancel()
}()
}
// --8<-- [end:exit-handler]
// setupLogger creates a logger instance.
// --8<-- [start:setup-logger].
func setupLogger() zerolog.Logger {
var writers []io.Writer
// the lab creates an empty file to indicate
// that we run in dev mode. If file exists, we
// log to console as well.
_, err := os.Stat("/tmp/.ndk-dev-mode")
if err == nil {
const logTimeFormat = "2006-01-02 15:04:05 MST"
consoleLogger := zerolog.ConsoleWriter{
Out: os.Stderr,
TimeFormat: logTimeFormat,
NoColor: true,
}
writers = append(writers, consoleLogger)
}
// A lumberjack logger with rotation settings.
fileLogger := &lumberjack.Logger{
Filename: "/var/log/greeter/greeter.log",
MaxSize: 2, // megabytes
MaxBackups: 3,
MaxAge: 28, // days
}
// --8<-- [start:syslog-logger]
var zsyslog zerolog.SyslogWriter
zsyslog, err = syslog.Dial("", "", syslog.LOG_INFO|syslog.LOG_LOCAL7, "ndk-greeter-go")
if err != nil {
panic(err)
}
// --8<-- [end:syslog-logger]
writers = append(writers, fileLogger, zsyslog)
mw := io.MultiWriter(writers...)
return zerolog.New(mw).With().Caller().Timestamp().Logger()
}
// --8<-- [end:setup-logger]