MongoDB 103 est un workshop permettant d'installer et de configurer un cluster MongoDB.
mongodb-103 par Chris WOODROW, Sébastien PRUNIER et Benjamin CAVY est distribué sous les termes de la licence Creative Commons - Attribution - NonCommercial - ShareAlike.
Ce workshop est basé sur la version 4.2.3 de MongoDB.
Nous considérons que vous avez déjà réalisé les workshops suivants :
Inspirez-vous de la documentation officielle : https://docs.mongodb.com/manual/tutorial/deploy-replica-set-for-testing/
L'idée est de démarrer 3 noeuds Mongo sur votre machine.
Dans un premier temps, créez les dossiers qui vont stocker les données des noeuds, par exemple :
mkdir ~/data/mongodb-cluster
cd ~/data/mongodb-cluster
mkdir rs0-0
mkdir rs0-1
mkdir rs0-2
Démarrez ensuite les 3 noeuds, en précisant pour chaque noeud un port différent et le dossier de stockage des données adéquat :
mongod --replSet rs0 --port 27017 --dbpath ~/data/mongodb-cluster/rs0-0
mongod --replSet rs0 --port 27018 --dbpath ~/data/mongodb-cluster/rs0-1
mongod --replSet rs0 --port 27019 --dbpath ~/data/mongodb-cluster/rs0-2
Connectez-vous ensuite au premier noeud :
mongo --port 27017
Définissez la configuration du cluster dans le shell Mongo :
rsconf = {
"_id": "rs0",
"members": [
{
"_id": 0,
"host": "localhost:27017"
},
{
"_id": 1,
"host": "localhost:27018"
},
{
"_id": 2,
"host": "localhost:27019"
}
]
}Puis initialisez le cluster à partir de cette configuration :
rs.initiate(rsconf)
Vérifiez enfin que le cluster est correctement créé à l'aide de la commande rs.status(). Recherchez dans le résultat de la commande le statut du noeud PRIMARY :
{
"_id": 0,
"name": "localhost:27017",
"health": 1,
"state": 1,
"stateStr": "PRIMARY",
"uptime": 194,
"optime": {
"ts": Timestamp(1581680710, 1),
"t": NumberLong("1")
},
"optimeDate": ISODate("2020-02-14T11:45:10Z"),
"syncingTo": "",
"syncSourceHost": "",
"syncSourceId": -1,
"infoMessage": "",
"electionTime": Timestamp(1581680589, 1),
"electionDate": ISODate("2020-02-14T11:43:09Z"),
"configVersion": 1,
"self": true,
"lastHeartbeatMessage": ""
}Essayez plusieurs choses sur le cluster Mongo :
- Arrêtez un noeud secondaire et vérifiez le statut du cluster, notamment celui du noeud arrêté
{
"_id": 2,
"name": "localhost:27019",
"health": 0,
"state": 8,
"stateStr": "(not reachable/healthy)",
"uptime": 0,
"optime": {
"ts": Timestamp(0, 0),
"t": NumberLong("-1")
},
"optimeDurable": {
"ts": Timestamp(0, 0),
"t": NumberLong("-1")
},
"optimeDate": ISODate("1970-01-01T00:00:00Z"),
"optimeDurableDate": ISODate("1970-01-01T00:00:00Z"),
"lastHeartbeat": ISODate("2020-02-14T13:05:39.473Z"),
"lastHeartbeatRecv": ISODate("2020-02-14T13:05:25.702Z"),
"pingMs": NumberLong("0"),
"lastHeartbeatMessage": "Error connecting to localhost:27019 (127.0.0.1:27019) :: caused by :: Connection refused",
"syncingTo": "",
"syncSourceHost": "",
"syncSourceId": -1,
"infoMessage": "",
"configVersion": -1
}- Arrêtez le deuxième noeud secondaire et regardez ce qui se passe au niveau du statut du seul noeud restant (il n'y a plus de noeud primaire)
{
"_id": 0,
"name": "localhost:27017",
"health": 1,
"state": 2,
"stateStr": "SECONDARY",
"uptime": 5085,
"optime": {
"ts": Timestamp(1581685598, 1),
"t": NumberLong("2")
},
"optimeDate": ISODate("2020-02-14T13:06:38Z"),
"syncingTo": "",
"syncSourceHost": "",
"syncSourceId": -1,
"infoMessage": "could not find member to sync from",
"configVersion": 1,
"self": true,
"lastHeartbeatMessage": ""
}- Essayez d'insérer un document via le seul noeud restant, l'écriture est impossible car il n'y a plus de noeud primaire
test> db.person.insert({name: "toto"})
WriteCommandError({
"operationTime": Timestamp(1581685598, 1),
"ok": 0,
"errmsg": "not master",
"code": 10107,
"codeName": "NotMaster",
"$clusterTime": {
"clusterTime": Timestamp(1581685598, 1),
"signature": {
"hash": BinData(0, "AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId": NumberLong("0")
}
}
})
-
Redémarrez les deux noeuds précédemment arrêtés, le cluster revient dans un état normal.
-
Arrêtez le noeud primaire et regardez l'évolution du statut du cluster : un nouveau noeud primaire a été élu. Prenez le temps d'analyser les logs des noeuds. Extraits intéressants :
2020-02-14T14:08:14.203+0100 I REPL [replexec-32] Member localhost:27019 is now in state RECOVERING
2020-02-14T14:08:14.703+0100 I REPL [replexec-32] Member localhost:27019 is now in state SECONDARY
2020-02-14T14:08:15.064+0100 I ELECTION [replexec-34] Starting an election, since we've seen no PRIMARY in the past 10000ms
2020-02-14T14:08:15.064+0100 I ELECTION [replexec-34] conducting a dry run election to see if we could be elected. current term: 3
2020-02-14T14:08:15.064+0100 I REPL [replexec-34] Scheduling remote command request for vote request: RemoteCommand 5742 -- target:localhost:27018 db:admin cmd:{ replSetRequestVotes: 1, setName: "rs0", dryRun: true, term: 3, candidateIndex: 0, configVersion: 1, lastCommittedOp: { ts: Timestamp(1581685598, 1), t: 2 } }
2020-02-14T14:08:15.064+0100 I REPL [replexec-34] Scheduling remote command request for vote request: RemoteCommand 5743 -- target:localhost:27019 db:admin cmd:{ replSetRequestVotes: 1, setName: "rs0", dryRun: true, term: 3, candidateIndex: 0, configVersion: 1, lastCommittedOp: { ts: Timestamp(1581685598, 1), t: 2 } }
2020-02-14T14:08:15.065+0100 I ELECTION [replexec-32] VoteRequester(term 3 dry run) received a yes vote from localhost:27018; response message: { term: 3, voteGranted: true, reason: "", ok: 1.0, $clusterTime: { clusterTime: Timestamp(1581685598, 1), signature: { hash: BinData(0, 0000000000000000000000000000000000000000), keyId: 0 } }, operationTime: Timestamp(1581685598, 1) }
2020-02-14T14:08:15.066+0100 I ELECTION [replexec-32] dry election run succeeded, running for election in term 4
2020-02-14T14:08:15.075+0100 I REPL [replexec-32] Scheduling remote command request for vote request: RemoteCommand 5744 -- target:localhost:27018 db:admin cmd:{ replSetRequestVotes: 1, setName: "rs0", dryRun: false, term: 4, candidateIndex: 0, configVersion: 1, lastCommittedOp: { ts: Timestamp(1581685598, 1), t: 2 } }
2020-02-14T14:08:15.076+0100 I REPL [replexec-32] Scheduling remote command request for vote request: RemoteCommand 5745 -- target:localhost:27019 db:admin cmd:{ replSetRequestVotes: 1, setName: "rs0", dryRun: false, term: 4, candidateIndex: 0, configVersion: 1, lastCommittedOp: { ts: Timestamp(1581685598, 1), t: 2 } }
2020-02-14T14:08:15.091+0100 I ELECTION [replexec-34] VoteRequester(term 4) received a yes vote from localhost:27019; response message: { term: 4, voteGranted: true, reason: "", ok: 1.0, $clusterTime: { clusterTime: Timestamp(1581685598, 1), signature: { hash: BinData(0, 0000000000000000000000000000000000000000), keyId: 0 } }, operationTime: Timestamp(1581685518, 1) }
2020-02-14T14:08:15.091+0100 I ELECTION [replexec-34] election succeeded, assuming primary role in term 4
2020-02-14T14:08:15.091+0100 I REPL [replexec-34] transition to PRIMARY from SECONDARY
...