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package main
import (
"context"
"crypto/tls"
"crypto/x509"
"fmt"
"io/ioutil"
"log"
"net"
"net/http"
"os"
"os/signal"
"path/filepath"
"strings"
"github.com/canonical/go-dqlite/v2/app"
"github.com/canonical/go-dqlite/v2/client"
"github.com/pkg/errors"
"github.com/spf13/cobra"
"golang.org/x/sys/unix"
)
func main() {
var api string
var db string
var join *[]string
var dir string
var verbose bool
var diskMode bool
var crt string
var key string
cmd := &cobra.Command{
Use: "dqlite-demo",
Short: "Demo application using dqlite",
Long: `This demo shows how to integrate a Go application with dqlite.
Complete documentation is available at https://github.com/canonical/go-dqlite`,
RunE: func(cmd *cobra.Command, args []string) error {
dir := filepath.Join(dir, db)
if err := os.MkdirAll(dir, 0755); err != nil {
return errors.Wrapf(err, "can't create %s", dir)
}
logFunc := func(l client.LogLevel, format string, a ...interface{}) {
if !verbose {
return
}
log.Printf(fmt.Sprintf("%s: %s: %s\n", api, l.String(), format), a...)
}
options := []app.Option{
app.WithAddress(db),
app.WithCluster(*join),
app.WithLogFunc(logFunc),
app.WithDiskMode(diskMode),
}
// Set TLS options
if (crt != "" && key == "") || (key != "" && crt == "") {
return fmt.Errorf("both TLS certificate and key must be given")
}
if crt != "" {
cert, err := tls.LoadX509KeyPair(crt, key)
if err != nil {
return err
}
data, err := ioutil.ReadFile(crt)
if err != nil {
return err
}
pool := x509.NewCertPool()
if !pool.AppendCertsFromPEM(data) {
return fmt.Errorf("bad certificate")
}
options = append(options, app.WithTLS(app.SimpleTLSConfig(cert, pool)))
}
app, err := app.New(dir, options...)
if err != nil {
return err
}
if err := app.Ready(context.Background()); err != nil {
return err
}
db, err := app.Open(context.Background(), "demo")
if err != nil {
return err
}
if _, err := db.Exec(schema); err != nil {
return err
}
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
key := strings.TrimLeft(r.URL.Path, "/")
result := ""
err = nil
switch r.Method {
case "GET":
row := db.QueryRow(query, key)
err = row.Scan(&result)
case "PUT":
result = "done"
value, _ := ioutil.ReadAll(r.Body)
_, err = db.Exec(update, key, string(value[:]))
default:
err = fmt.Errorf("unsupported method")
}
if err == nil {
fmt.Fprint(w, result)
} else {
http.Error(w, err.Error(), 500)
}
})
listener, err := net.Listen("tcp", api)
if err != nil {
return err
}
go http.Serve(listener, nil)
ch := make(chan os.Signal, 32)
signal.Notify(ch, unix.SIGPWR)
signal.Notify(ch, unix.SIGINT)
signal.Notify(ch, unix.SIGQUIT)
signal.Notify(ch, unix.SIGTERM)
<-ch
listener.Close()
db.Close()
app.Handover(context.Background())
app.Close()
return nil
},
}
flags := cmd.Flags()
flags.StringVarP(&api, "api", "a", "", "address used to expose the demo API")
flags.StringVarP(&db, "db", "d", "", "address used for internal database replication")
join = flags.StringSliceP("join", "j", nil, "database addresses of existing nodes")
flags.StringVarP(&dir, "dir", "D", "/tmp/dqlite-demo", "data directory")
flags.BoolVarP(&verbose, "verbose", "v", false, "verbose logging")
flags.BoolVar(&diskMode, "disk", defaultDiskMode, "Warning: Unstable, Experimental. Set this flag to enable dqlite's disk-mode.")
flags.StringVarP(&crt, "cert", "c", "", "public TLS cert")
flags.StringVarP(&key, "key", "k", "", "private TLS key")
cmd.MarkFlagRequired("api")
cmd.MarkFlagRequired("db")
if err := cmd.Execute(); err != nil {
os.Exit(1)
}
}
const (
schema = "CREATE TABLE IF NOT EXISTS model (key TEXT, value TEXT, UNIQUE(key))"
query = "SELECT value FROM model WHERE key = ?"
update = "INSERT OR REPLACE INTO model(key, value) VALUES(?, ?)"
defaultDiskMode = false
)
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