Neo4j Scaling

Introduction:

Insights has introduced a unique feature called Neo4j Scaling which helps to create read only replica database of your master neo4j. It will capture and persist all the Change Data Capture (CDC) events from the master neo4j in real time with least possible delay. The replica database will be used for dash boarding which will considerably reduce load on main write server. This feature helps to scale the master neo4j database within few clicks.

Prerequisites:

Insights >= v10.5
Insights supports Neo4j (4.4.4) database for this functionality.
Install neo4j streams plugin in all database servers (i.e. master & replicas)
Configure & set up Kafka server.
Only Admin can access this functionality.

Steps to set up Kafka:

Step 1: Download Kafka.

Follow below steps & update the properties:

tar -xzf kafka_2.13-3.6.0.tgz

vi kafka_2.13-3.6.0/config/server.properties

#Properties

listeners=PLAINTEXT://0.0.0.0:9092

advertised.linsteners=PLAINTEXT://[Kafka_Server_IP]:9092

log.dirs=/tmp/kafka-logs

log.retention.hours=5

zookeeper.connect=[Kafka_Server_IP]:2181

Step 2: Start the zookeeper.

bin/zookeeper-server-start.sh config/zookeeper.properties

Step 3: Start the Kafka.

bin/kafka-server-start.sh config/server.properties

Step 4: To monitor Kafka, download the Kafka-UI image from docker hub.

docker run -it -p 8080:8080 -e DYNAMIC_CONFIG_ENABLED=true --net=host provectuslabs/kafka-ui

For more info click here.

Keep the Master & Replica neo4j credentials same.

Steps to install neo4j streams plugin:

Step 1: Download the neo4j streams plugin.

Step 2: Create a streams.conf file inside $NEO4J_HOME/conf and add the below properties.

Kafka Properties

kafka.bootstrap.servers=[Kafka_Server_IP]:9092
kafka.acks=1
kafka.retries=2
kafka.batch.size=0
kafka.buffer.memory=33554432
kafka.reindex.batch.size=1000
kafka.session.timeout.ms=25000
kafka.connection.timeout.ms=20000
kafka.replication=1
kafka.linger.ms=1
kafka.transactional.id=
kafka.topic.discovery.polling.interval=300000
kafka.streams.log.compaction.strategy=delete

For Master Neo4j Server-

streams.source.topic.nodes.<TOPIC_NAME>=DATA{*}
streams.source.topic.relationships.<TOPIC_NAME>=BRANCH_HAS_COMMITS{*};BRANCH_HAS_PULL_REQUESTS{*};FILE_HAS_COMMITS{*}
streams.source.topic.relationships. insights-topic.key_strategy=all
streams.source.enabled=true
streams.sink.enabled=false

DATA{*} includes other Insights labels (i.e. JIRA, GITHUB, SONAR, JENKINS etc.)

Mention all the relationships which you want to capture.

For Replica Neo4j Server-

kafka.group.id=replica1
streams.source.enabled=false
streams.sink.enabled=true
streams.sink.topic.cdc.schema=insights-topic
streams.sink.poll.interval=300

In Neo4j - CREATE INDEX on :DATA(uuid);

For more info click here.

App Server: On which Insights App is running.
Master Server: On which master Neo4j is running.
Replica Server: New server to scale master Neo4j.

Steps to set up SSH:

App Server:

Note: User should have root level access.

# Install netcat
sudo yum install -y nc
su – [user_name]  
cd /home/[user_name]/.ssh
# IF THE USER DOESN'T HAVE PUBLIC_KEY (id_rsa.pub). CREATE IT USING BELOW keygen COMMAND ELSE IGNORE. 
ssh-keygen -t rsa
cd .ssh/
# CREATE AN App_Server_key FILE & PASTE THE PUBLIC_KEY (id_rsa.pub)
App_Server_key >> authorized_keys

App_Server_key file is critical & can be used further in below steps.

Replica Server:

# Install netcat
sudo yum install -y nc
# CREATE A REPLICA_USER
sudo useradd replica_user
# CREATE A REPLICA_GROUP
sudo groupadd replica_group       
usermod -aG replica_group replica_user
su – replica_user
cd/home/[replica_user]
# TO CREATE REPLICA_USER PUBLIC_KEY (id_rsa.pub)
ssh-keygen -t rsa
cd .ssh/
# CREATE A Replica1_Server_key FILE & PASTE PUBLIC_KEY (id_rsa.pub)
cat [App_Server_Key] >> authorized_keys  (Copy App Server key)
chmod 600 authorized_keys              
exit

Replica1_Server_key file is critical & can be used further in below steps.

# PROVIDING ONLY SPECIFIC PERMISSIONS TO SPECIFIC DIRECTORY & FILE.
sudo chgrp -R replica_group /opt/NEO4J_HOME/neo4j-Insights/data
chmod -R g+rw /opt/NEO4J_HOME/neo4j-Insights/data
sudo chgrp replica_group /opt/NEO4J_HOME/neo4j-Insights/conf/streams.conf
chmod g+rw /opt/NEO4J_HOME/neo4j-Insights/conf/streams.conf

visudo 
Cmnd_Alias CUSTOM_SERVICES = /sbin/service Neo4j stop, /sbin/service Neo4j start, /sbin/service Neo4j status
replica_user ALL=NOPASSWD:CUSTOM_SERVICES

Be cautious while doing below steps. This may lead to login issue.

Don’t forget to add master_user (user which you use to login) in AllowUsers.

sudo vi /etc/ssh/sshd_config  
AllowUsers  root   ec2-user   replica_user  <master_user>
sudo systemctl restart sshd

Master Server:

# Install netcat
sudo yum install -y nc
# CREATE A REPLICA_USER
sudo useradd replica_user
# CREATE A REPLICA_GROUP
sudo groupadd replica_group
usermod -aG replica_group replica_user
su - replica_user
cd /home/[replica_user]/.ssh
# TO CREATE REPLICA_USER PUBLIC_KEY (id_rsa.pub)
ssh-keygen -t rsa        
cd .ssh/
# CREATE A Replica1_Server_key FILE & PASTE PUBLIC_KEY (id_rsa.pub)
cat [Replica1_Server_key] >> authorized_keys  (Copy Replica Server key)
cat [App_Server_Key] >> authorized_keys  (Copy App Server key)
chmod 600 authorized_keys              
exit

# PROVIDING ONLY SPECIFIC PERMISSIONS TO SPECIFIC DIRECTORY & FILE.
sudo chgrp replica_group /opt/NEO4J_HOME/neo4j-Insights/data
chmod g+r /opt/NEO4J_HOME/neo4j-Insights/data
sudo chgrp replica_group /opt/NEO4J_HOME/neo4j-Insights/conf/streams.conf
chmod g+rw /opt/NEO4J_HOME/neo4j-Insights/conf/streams.conf

visudo
Cmnd_Alias CUSTOM_SERVICES = /sbin/service Neo4j stop, /sbin/service Neo4j start, /sbin/service Neo4j status
replica_user ALL=NOPASSWD:CUSTOM_SERVICES

Be cautious while doing below steps. This may lead to login issue.

Don’t forget to add master_user (user which you use to login) in AllowUsers.

sudo vi /etc/ssh/sshd_config  
AllowUsers   root   ec2-user   replica_user  <master_user>
sudo systemctl restart sshd

Steps to configure Neo4j Scaling:

Make sure Replica server is set up & neo4j is up & running on it.
Make sure Replica Daemon agent should be running.
Stop Neo4j on Master server & Insights Engine on App server.

Step 1: Navigate to Neo4j Scaling screen click on the configure button to configure source & replica details as shown below.

Step 2: After configuring source & replica details, click on the save button to save the configuration. Wait for few minutes & refresh the front screen, replica details will get displayed.

Step 3: To see the status logs, click on the details button. It will display resync status logs as shown below.

Step 4: Once you get “Replica resynced successfully” message in resync status logs.

Restart the Neo4j on Master server & Insights Engine on App server.

Step 5: To remove a replica, select that replica & click on the delete button. You can view the delete status log inside the additional details screen as shown below.

Make sure Replica server is set up & neo4j is up & running on it.
Stop Neo4j on Master server & Insights Engine on App server.

Step 6: To resync all replicas, click on the resync button. It will resync all replicas.