2026-03-12 21:01:38

tiddlywiki/MongoDB - replication setup.txt

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+~~ server names: 
+~~              ajara
+~~              atrisia
+~~              anaxes
+
+
+~~ enable SCRAM authentification on ALL MongoDB instances
+mongo
+> use admin
+> db.createUser({ user: "superhero",  pwd: "secret", roles: ["root"]});
+> db.shutdownServer();
+
+~~ add in MongoDB configuration file ->
+security:
+  authorization: 'enabled'
+<-------------------------------------
+
+~~ start MongoDB instance
+/app/mongodb/product/current_version/bin/mongod --config=/app/mongodb/conf/mongod.conf --logpath=/app/mongodb/log/mongod.log --fork
+
+~~ test connection
+mongo --username=superhero --password=secret
+
+~~ for internal communication between instances we will use a basic keyFile method
+
+~~ generate keyfile 
+openssl rand -base64 756 > /app/mongodb/conf/keyfile.basic
+chmod 600 /app/mongodb/conf/keyfile.basic
+
+~~ add the keyfile in MongoDB configuration file ->
+security:
+  authorization: 'enabled'
+  keyFile: /app/mongodb/conf/keyfile.basic
+<-------------------------------------
+
+~~ restart MongoDB instance and test connection again
+/app/mongodb/product/current_version/bin/mongod --config=/app/mongodb/conf/mongod.conf --shutdown
+/app/mongodb/product/current_version/bin/mongod --config=/app/mongodb/conf/mongod.conf --logpath=/app/mongodb/log/mongod.log --fork
+
+mongo --username=superhero --password=secret
+
+~~ repeat theses operations on other 2 MongoDB instances using the SAME keyfile generated for the first instance
+
+~~ for all MongoDB instances, declare the replication in configuration file
+
+------------------------------------------>
+replication:
+  replSetName: rs0
+<-----------------------------------------
+
+
+mongo --username=superhero --password=secret
+
+rsconf = {
+           _id: "rs0",
+           members: [
+                      {
+                       _id: 0,
+                       host: "ajara:27017"
+                      }
+                    ]
+         }
+
+
+rs.initiate(rsconf);
+
+rs.add('atrisia:27017');
+rs.add('anaxes:27017');
+
+rs.conf();
+rs.status();
+
+
+~~ ckeck if replication works
+~~ on PRIMARY instance create a database and a collection
+rs0:PRIMARY> use db01;
+rs0:PRIMARY> db.movies.insertOne({"title" : "Stand by Me"});
+
+~~ on SECONDARIES check if the collection has been replicated
+~~ note that a slave, before running a query, we should activate the read-only acces using the following command
+rs0:SECONDARY> rs.slaveOk();
+
+rs0:SECONDARY> use db01;
+rs0:SECONDARY> db.movies.find();
+
+~~ finaly, drop the test database from the master node
+rs0:PRIMARY> db.dropDatabase();
+
+~~ to user on SECONDARY replica to display lag and oplog size
+db.getReplicationInfo();
+
+~~ to find the mester of a replica set, use the following command on any member of replica set
+db.isMaster();
+
+~~ get replica set congig
+config = rs.conf();
+
+~~ remove a member from a replica set
+rs.remove('anaxes:27017');
+rs.reconfig(config, {force: true});