Fink simulator

For testing purposes, Fink uses an external service to simulate incoming streams: fink-alert-simulator. With this stream simulator package, you can easily develop applications locally and deploy at scale only when you are ready!

Installation

See Getting Started to install the simulator.

Using ZTF data

The service is provided through docker-compose, and include Kafka and Zookeeper clusters deployment. The simulator generates the stream from alerts stored on disk. We provide a script to download a subset of ZTF alerts that will be used to generate streams:

cd ${FINK_HOME}/datasim
./download_ztf_alert_data.sh
# ...download 499 alerts

You can change this folder with your data, but make sure you correctly set the schema and the data path in the configuration:

# in configuration file
FINK_ALERT_SCHEMA=...
FINK_DATA_SIM=...

Sending alerts to the broker

By default alerts will be published on the port 29092 (localhost), but you can change it in the configuration file (see conf/fink-alert-simulator.conf). To start the simulator and send alerts, just execute:

# the --docker specifies a local run using docker-compose
fink_simulator --docker

With the default configuration, it will generate 4 observations (NOBSERVATIONS) of 3 alerts each (NALERTS_PER_OBS). Data will be published on the IP/PORT localhost:29092 (KAFKA_IPPORT_SIM) in a topic called ztf-stream-sim (KAFKA_TOPIC), at regular interval of 5 seconds between two observations (TIME_INTERVAL). You can change all of it in the configuration file. Note you cannot publish more alerts than what is available on disk. All fink-broker services can be run on the simulated stream by just specifying the argument --simulator:

fink start <service> --simulator

Always make sure that the Kafka properties are the same between the fink-alert-simulator (producer) and the fink-broker (consumer):

##############
# This block is in both
#   * conf/fink.conf (fink-broker)
#   * conf/fink-alert-simulator.conf (fink-alert-simulator)
##############

# Local mode (Kafka cluster is spun up on-the-fly in docker).
KAFKA_PORT_SIM=29092
KAFKA_IPPORT_SIM="localhost:${KAFKA_PORT_SIM}"

# Cluster mode - you would a Kafka cluster installed with write mode.
KAFKA_IPPORT=""

# Topic name for the producer
KAFKA_TOPIC="ztf-stream-sim"

For example for demo purposing, you can easily start the monitoring service on the simulated stream with:

fink start checkstream --simulator

and watch the incoming stream after sending alerts (fink_simulator --docker).