cmd/swarm/swarm-snapshot: swarm snapshot generator (#18453)

* cmd/swarm/swarm-snapshot: add binary to create network snapshots

* cmd/swarm/swarm-snapshot: refactor and extend tests

* p2p/simulations: remove unused triggerChecks func and fix linter

* internal/cmdtest: raise the timeout for killing TestCmd

* cmd/swarm/swarm-snapshot: add more comments and other minor adjustments

* cmd/swarm/swarm-snapshot: remove redundant check in createSnapshot

* cmd/swarm/swarm-snapshot: change comment wording

* p2p/simulations: revert Simulation.Run from master

https://github.com/ethersphere/go-ethereum/pull/1077/files#r247078904

* cmd/swarm/swarm-snapshot: address pr comments

* swarm/network/simulations/discovery: removed snapshot write to file

* cmd/swarm/swarm-snapshot, swarm/network/simulations: removed redundant connection event check, fixed lint error

cmd/swarm/swarm-snapshot/create.go

@@ -0,0 +1,157 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/node"
+	"github.com/ethereum/go-ethereum/p2p/simulations"
+	"github.com/ethereum/go-ethereum/p2p/simulations/adapters"
+	"github.com/ethereum/go-ethereum/swarm/network"
+	"github.com/ethereum/go-ethereum/swarm/network/simulation"
+	cli "gopkg.in/urfave/cli.v1"
+)
+
+// create is used as the entry function for "create" app command.
+func create(ctx *cli.Context) error {
+	log.PrintOrigins(true)
+	log.Root().SetHandler(log.LvlFilterHandler(log.Lvl(ctx.Int("verbosity")), log.StreamHandler(os.Stdout, log.TerminalFormat(true))))
+
+	if len(ctx.Args()) < 1 {
+		return errors.New("argument should be the filename to verify or write-to")
+	}
+	filename, err := touchPath(ctx.Args()[0])
+	if err != nil {
+		return err
+	}
+	return createSnapshot(filename, ctx.Int("nodes"), strings.Split(ctx.String("services"), ","))
+}
+
+// createSnapshot creates a new snapshot on filesystem with provided filename,
+// number of nodes and service names.
+func createSnapshot(filename string, nodes int, services []string) (err error) {
+	log.Debug("create snapshot", "filename", filename, "nodes", nodes, "services", services)
+
+	sim := simulation.New(map[string]simulation.ServiceFunc{
+		"bzz": func(ctx *adapters.ServiceContext, b *sync.Map) (node.Service, func(), error) {
+			addr := network.NewAddr(ctx.Config.Node())
+			kad := network.NewKademlia(addr.Over(), network.NewKadParams())
+			hp := network.NewHiveParams()
+			hp.KeepAliveInterval = time.Duration(200) * time.Millisecond
+			hp.Discovery = true // discovery must be enabled when creating a snapshot
+
+			config := &network.BzzConfig{
+				OverlayAddr:  addr.Over(),
+				UnderlayAddr: addr.Under(),
+				HiveParams:   hp,
+			}
+			return network.NewBzz(config, kad, nil, nil, nil), nil, nil
+		},
+	})
+	defer sim.Close()
+
+	_, err = sim.AddNodes(nodes)
+	if err != nil {
+		return fmt.Errorf("add nodes: %v", err)
+	}
+
+	err = sim.Net.ConnectNodesRing(nil)
+	if err != nil {
+		return fmt.Errorf("connect nodes: %v", err)
+	}
+
+	ctx, cancelSimRun := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer cancelSimRun()
+	if _, err := sim.WaitTillHealthy(ctx); err != nil {
+		return fmt.Errorf("wait for healthy kademlia: %v", err)
+	}
+
+	var snap *simulations.Snapshot
+	if len(services) > 0 {
+		// If service names are provided, include them in the snapshot.
+		// But, check if "bzz" service is not among them to remove it
+		// form the snapshot as it exists on snapshot creation.
+		var removeServices []string
+		var wantBzz bool
+		for _, s := range services {
+			if s == "bzz" {
+				wantBzz = true
+				break
+			}
+		}
+		if !wantBzz {
+			removeServices = []string{"bzz"}
+		}
+		snap, err = sim.Net.SnapshotWithServices(services, removeServices)
+	} else {
+		snap, err = sim.Net.Snapshot()
+	}
+	if err != nil {
+		return fmt.Errorf("create snapshot: %v", err)
+	}
+	jsonsnapshot, err := json.Marshal(snap)
+	if err != nil {
+		return fmt.Errorf("json encode snapshot: %v", err)
+	}
+	return ioutil.WriteFile(filename, jsonsnapshot, 0666)
+}
+
+// touchPath creates an empty file and all subdirectories
+// that are missing.
+func touchPath(filename string) (string, error) {
+	if path.IsAbs(filename) {
+		if _, err := os.Stat(filename); err == nil {
+			// path exists, overwrite
+			return filename, nil
+		}
+	}
+
+	d, f := path.Split(filename)
+	dir, err := filepath.Abs(filepath.Dir(os.Args[0]))
+	if err != nil {
+		return "", err
+	}
+
+	_, err = os.Stat(path.Join(dir, filename))
+	if err == nil {
+		// path exists, overwrite
+		return filename, nil
+	}
+
+	dirPath := path.Join(dir, d)
+	filePath := path.Join(dirPath, f)
+	if d != "" {
+		err = os.MkdirAll(dirPath, os.ModeDir)
+		if err != nil {
+			return "", err
+		}
+	}
+
+	return filePath, nil
+}