Scale Flow Processing with Sentinel

When your flows data collection volume increases to the point that Horizon is too busy processing flows, you can add one or more Sentinels to do the processing instead. Sentinel can do the following:

Consume flow messages from Minions through a message broker (ActiveMQ or Apache Kafka)
Persist network flow messages to Elasticsearch
Generate and send events to the Horizon core instance via message broker

Figure 1. Flow integration with Sentinel

Before you begin

Make sure you have the following:

Basic flows environment set up
Sentinel installed on your system
PostgreSQL, Elasticsearch, and REST endpoint to Horizon core instance running and reachable from the Sentinel node(s)
Message broker (ActiveMQ or Apache Kafka) running and reachable from the Sentinel node(s)
Credentials for authentication configured for the message broker, Elasticsearch, and the PostgreSQL database

You must set configuration in the etc directory relative to the Horizon Sentinel home directory ${SENTINEL_HOME}. Depending on your operating system, the home directory is /usr/share/sentinel for Debian/Ubuntu or /opt/sentinel for CentOS/RHEL.

Repeat the following steps on each Sentinel node.

Configure access to PostgreSQL database

Connect to the Sentinel Karaf shell via SSH

ssh -p 8301 admin@localhost

Configure access to the PostgreSQL database

config:edit org.opennms.netmgt.distributed.datasource
config:property-set datasource.url jdbc:postgresql://postgres-ip:postgres-port/opennms-db-name(1)
config:property-set datasource.username my-db-user(2)
config:property-set datasource.password my-db-password(3)
config:property-set datasource.databaseName opennms-db-name(4)
config:update

1	JDBC connection string; replace `postgres-ip`, `postgres-port`, and `opennms-db-name` accordingly.
2	PostgreSQL user name with read/write access to the `opennms-db-name` database
3	PostgreSQL password for `my-db-user` user
4	Database name of your Horizon Core instance database

Configure access to Elasticsearch

Connect to the Sentinel Karaf shell via SSH

ssh -p 8301 admin@localhost

Configure access to persist flows to Elasticsearch

config:edit org.opennms.features.flows.persistence.elastic
config:property-set elasticUrl http://elastic-ip:9200(1)
config:property-set elasticIndexStrategy hourly(2)
config:property-set settings.index.number_of_replicas 0(3)
config:property-set connTimeout 30000(4)
config:property-set readTimeout 60000(5)
config:update

1	Replace with a URL to the Elasticsearch cluster.
2	Specify an index strategy.
3	Set number of replicas; 0 is a default. In production you should have at least 1.
4	Timeout, in milliseconds, Sentinel waits to connect to the Elasticsearch cluster.
5	Read timeout when data is fetched from the Elasticsearch cluster.

Additional configuration properties are documented in General Elasticsearch configuration. Be sure to also set the indexPrefix property when using a single Elasticsearch cluster with multiple Horizon instances. If you set the indexPrefix property, all Sentinel instances on the same Horizon instance should use the same value.

Set up message broker

Kafka
ActiveMQ

Create a file in etc/featuresBoot.d/flows.boot

sudo vi etc/featuresBoot.d/flows.boot

Add the following features to Sentinel on startup

sentinel-jsonstore-postgres
sentinel-blobstore-noop
sentinel-kafka
sentinel-flows

(Optional) Configure a custom topic prefix

sudo vi etc/custom.system.properties

org.opennms.instance.id=OpenNMS(1)

1	Replace `OpenNMS` with the same topic prefix that the target instance of Horizon Core uses.

Connect to the Karaf shell via SSH

ssh -p 8301 admin@localhost

Configure Sentinel tracing and REST endpoint

config:edit org.opennms.sentinel.controller
config:property-set location SENTINEL(1)
config:property-set id 00000000-0000-0000-0000-000000ddba11(2)
config:update

1	A location string is used to assign the Sentinel to a monitoring location. This can be an existing location or a new location and does not impact the messages that this Sentinel will process.
2	Unique identifier you define to use as a node label for monitoring the Sentinel instance within Horizon. This can be a GUID or a hostname.

Configure Sentinel as Kafka consumer for flow messages

config:edit org.opennms.core.ipc.sink.kafka.consumer(1)
config:property-set bootstrap.servers my-kafka-ip-1:9092,my-kafka-ip-2:9092(2)
config:property-set group.id OpenNMS(3)
config:update

1	Edit the configuration for the flow consumer from Kafka.
2	Connect to the following Kafka nodes and adjust the IPs or FQDNs with the Kafka port (9092) accordingly.
3	(Optional) When using the same Kafka cluster for multiple Horizon instances, the `group.id` value should be the same as the `org.opennms.instance.id` value in the `etc/custom.system.properties` file.

The complete set of configuration properties needed for your cluster depends on your Kafka deployment. Refer to the Kafka configuration that Horizon Core and Minions use, as the properties required for those components will likely be similar to the properties needed in the Sentinel’s configuration.

Configure Sentinel to generate and send events (sink) using the same set of properties from the previous step

config:edit org.opennms.core.ipc.sink.kafka
config:property-set bootstrap.servers my-kafka-ip-1:9092,my-kafka-ip-2:9092
config:property-set group.id OpenNMS
config:update

Exit the Karaf Shell with Ctrl+d

Restart the Sentinel to apply the configuration

sudo systemctl restart sentinel

Run health-check to verify configuration

opennms:health-check

Ensure features are installed and work properly

Verifying the health of the container

Verifying installed bundles                    [ Success  ]
Connecting to Kafka from Sink Producer         [ Success  ]
Connecting to Kafka from Sink Consumer         [ Success  ]
Retrieving NodeDao                             [ Success  ]
Connecting to ElasticSearch ReST API (Flows)   [ Success  ]

=> Everything is awesome

Create a file in etc/featuresBoot.d/flows.boot

sudo vi etc/featuresBoot.d/flows.boot

Add the following features to Sentinel on startup

sentinel-jsonstore-postgres
sentinel-blobstore-noop
sentinel-jms
sentinel-flows

Connect to the Karaf shell via SSH

ssh -p 8301 admin@localhost

Configure Sentinel tracing, REST and ActiveMQ endpoints

config:edit org.opennms.sentinel.controller
config:property-set location SENTINEL(1)
config:property-set id 00000000-0000-0000-0000-000000ddba11(2)
config:property-set broker-url failover:tcp://my-activemq-ip:61616(3)
config:update

1	A location string is used to assign the Sentinel to a monitoring location. This can be an existing location or a new location and does not impact the messages that this Sentinel will process.
2	Unique identifier you define to use as a node label for monitoring the Sentinel instance within Horizon. This can be a GUID or a hostname.
3	URL that points to ActiveMQ broker.

Configure the credentials and exit Karaf shell

opennms:scv-set opennms.broker my-sentinel-user my-sentinel-password(1)

1	Set the credentials for the ActiveMQ message broker

The credentials are encrypted on disk in ${SENTINEL_HOME}/etc/scv.jce.

Exit the Karaf Shell with Ctrl+d

Restart the Sentinel to apply the configuration

sudo systemctl restart sentinel

Run health-check to verify configuration

opennms:health-check

Ensure features are installed and work properly

Verifying the health of the container

Verifying installed bundles                    [ Success  ]
Retrieving NodeDao                             [ Success  ]
Connecting to JMS Broker                       [ Success  ]
Connecting to ElasticSearch ReST API (Flows)   [ Success  ]

=> Everything is awesome

Enable flow processing protocols

Connect to the Sentinel Karaf shell via SSH

ssh -p 8301 admin@localhost

Netflow v5
Netflow v9
sFlow
IPFIX

config:edit --alias netflow5 --factory org.opennms.features.telemetry.adapters
config:property-set name Netflow-5(1)
config:property-set adapters.0.name Netflow-5-Adapter(2)
config:property-set adapters.0.class-name org.opennms.netmgt.telemetry.protocols.netflow.adapter.netflow5.Netflow5Adapter(3)
config:update

1	Queue name from which Sentinel will fetch messages. The Minion parser name for Netflow v5 must match this name. By default, for Horizon components, the queue name convention is `Netflow-5`.
2	Set a name for the Netflow v5 adapter.
3	Assign an adapter to enrich Netflow v5 messages.

The configuration is persisted with the suffix specified as alias in etc/org.opennms.features.telemetry.adapters-netflow5.cfg.

When processing multiple protocols from the same queue, include additional adapters by adding additional name and class-name properties, increasing the index 0 for each pair.

Run health-check to verify adapter configuration

opennms:health-check

Ensure the configured flow adapters work properly

Verifying the health of the container

...
Verifying Adapter Netflow-5-Adapter (org.opennms.netmgt.telemetry.protocols.netflow.adapter.netflow5.Netflow5Adapter)   [ Success  ]

config:edit --alias netflow9 --factory org.opennms.features.telemetry.adapters
config:property-set name Netflow-9(1)
config:property-set adapters.0.name Netflow-9-Adapter(2)
config:property-set adapters.0.class-name org.opennms.netmgt.telemetry.protocols.netflow.adapter.netflow9.Netflow9Adapter(3)
config:update

1	Queue name from which Sentinel will fetch messages. The Minion parser name for Netflow v9 must match this name. By default, for Horizon components, the queue name convention is `Netflow-9`.
2	Set a name for the Netflow v9 adapter.
3	Assign an adapter to enrich Netflow v9 messages.

The configuration is persisted with the suffix specified as alias in etc/org.opennms.features.telemetry.adapters-netflow9.cfg.

When processing multiple protocols from the same queue, include additional adapters by adding additional name and class-name properties, increasing the index 0 for each pair.

Run health-check to verify adapter configuration

opennms:health-check

Ensure the configured flow adapters work properly

Verifying the health of the container

...
Verifying Adapter Netflow-9-Adapter (org.opennms.netmgt.telemetry.protocols.netflow.adapter.netflow9.Netflow9Adapter)   [ Success  ]

config:edit --alias sflow --factory org.opennms.features.telemetry.adapters
config:property-set name SFlow(1)
config:property-set adapters.0.name SFlow-Adapter(2)
config:property-set adapters.0.class-name org.opennms.netmgt.telemetry.protocols.sflow.adapter.SFlowAdapter(3)
config:update

1	Queue name from which Sentinel will fetch messages. The Minion parser name for sFlow must match this name. By default, for Horizon components, the queue name convention is `SFlow`.
2	Set a name for the sFlow adapter.
3	Assign an adapter to enrich sFlow messages.

The configuration is persisted with the suffix specified as alias in etc/org.opennms.features.telemetry.adapters-sflow.cfg.

When processing multiple protocols from the same queue, include additional adapters by adding additional name and class-name properties, increasing the index 0 for each pair.

Run health-check to verify adapter configuration

opennms:health-check

Ensure the configured flow adapters work properly

Verifying the health of the container

...
Verifying Adapter SFlow-Adapter (org.opennms.netmgt.telemetry.protocols.sflow.adapter.SFlowAdapter)   [ Success  ]

config:edit --alias ipfix --factory org.opennms.features.telemetry.adapters
config:property-set name IPFIX(1)
config:property-set adapters.0.name IPFIX-Adapter(2)
config:property-set adapters.0.class-name org.opennms.netmgt.telemetry.protocols.netflow.adapter.ipfix.IpfixAdapter(3)
config:update

1	Queue name from which Sentinel will fetch messages. The Minion parser name for IPFIX must match this name. By default, for Horizon components, the queue name convention is `IPFIX`.
2	Set a name for the IPFIX adapter.
3	Assign an adapter to enrich IPFIX messages.

The configuration is persisted with the suffix specified as alias in etc/org.opennms.features.telemetry.adapters-ipfix.cfg.

When processing multiple protocols from the same queue, include additional adapters by adding additional name and class-name properties, increasing the index 0 for each pair.

Run health-check to verify adapter configuration

opennms:health-check

Ensure the configured flow adapters work properly

Verifying the health of the container

...
Verifying Adapter IPFIX-Adapter (org.opennms.netmgt.telemetry.protocols.netflow.adapter.ipfix.IpfixAdapter)   [ Success  ]