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// Copyright 2015 The etcd Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package raft
import (
pb ""
// Bootstrap initializes the RawNode for first use by appending configuration
// changes for the supplied peers. This method returns an error if the Storage
// is nonempty.
// It is recommended that instead of calling this method, applications bootstrap
// their state manually by setting up a Storage that has a first index > 1 and
// which stores the desired ConfState as its InitialState.
func (rn *RawNode) Bootstrap(peers []Peer) error {
if len(peers) == 0 {
return errors.New("must provide at least one peer to Bootstrap")
lastIndex, err :=
if err != nil {
return err
if lastIndex != 0 {
return errors.New("can't bootstrap a nonempty Storage")
// We've faked out initial entries above, but nothing has been
// persisted. Start with an empty HardState (thus the first Ready will
// emit a HardState update for the app to persist).
rn.prevHardSt = emptyState
// TODO(tbg): remove StartNode and give the application the right tools to
// bootstrap the initial membership in a cleaner way.
rn.raft.becomeFollower(1, None)
ents := make([]pb.Entry, len(peers))
for i, peer := range peers {
cc := pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: peer.ID, Context: peer.Context}
data, err := cc.Marshal()
if err != nil {
return err
ents[i] = pb.Entry{Type: pb.EntryConfChange, Term: 1, Index: uint64(i + 1), Data: data}
// Now apply them, mainly so that the application can call Campaign
// immediately after StartNode in tests. Note that these nodes will
// be added to raft twice: here and when the application's Ready
// loop calls ApplyConfChange. The calls to addNode must come after
// all calls to raftLog.append so is set after these
// bootstrapping entries (it is an error if we try to append these
// entries since they have already been committed).
// We do not set raftLog.applied so the application will be able
// to observe all conf changes via Ready.CommittedEntries.
// TODO(bdarnell): These entries are still unstable; do we need to preserve
// the invariant that committed < unstable?
rn.raft.raftLog.committed = uint64(len(ents))
for _, peer := range peers {
rn.raft.applyConfChange(pb.ConfChange{NodeID: peer.ID, Type: pb.ConfChangeAddNode}.AsV2())
return nil