compose/example/backend/main.go

113 lines
2.9 KiB
Go

/*
Copyright (c) 2019 Docker Inc.
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use, copy,
modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH
THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package main
import (
"context"
"fmt"
"net"
"os"
"os/signal"
"syscall"
"github.com/docker/api/server"
_ "github.com/gogo/googleapis/google/rpc"
_ "github.com/gogo/protobuf/types"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
func main() {
app := cli.NewApp()
app.Name = "example"
app.Usage = "example backend"
app.Description = ""
app.UseShortOptionHandling = true
app.EnableBashCompletion = true
app.Flags = []cli.Flag{
cli.BoolFlag{
Name: "debug",
Usage: "enable debug output in the logs",
},
cli.StringFlag{
Name: "address,a",
Usage: "address of the server",
},
}
app.Before = func(clix *cli.Context) error {
if clix.GlobalBool("debug") {
logrus.SetLevel(logrus.DebugLevel)
}
return nil
}
app.Action = func(clix *cli.Context) error {
ctx, cancel := cancelContext()
defer cancel()
// create a new GRPC server with the provided server package
s := server.New()
// listen on a socket to accept connects
l, err := net.Listen("tcp", clix.GlobalString("address"))
if err != nil {
return errors.Wrap(err, "listen tcp")
}
defer l.Close()
// handle context being closed or canceled
go func() {
<-ctx.Done()
logrus.Info("backend signaled to stop")
s.Stop()
}()
logrus.WithField("address", clix.GlobalString("address")).Info("serving daemon API")
// start the GRPC server to serve on the listener
return s.Serve(l)
}
if err := app.Run(os.Args); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
// cancelContext is a context that is canceled when a signal is
// sent to the process
func cancelContext() (context.Context, func()) {
ctx, cancel := context.WithCancel(context.Background())
s := make(chan os.Signal)
signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
go func() {
<-s
cancel()
}()
return ctx, cancel
}