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Fink client

Version 03/06/2026

This manual has been tested for fink-client version 12.0. In case of trouble, send us an email (contact@fink-broker.org) or open an issue .

Purpose

The Fink ecosystem has evolved rapidly in recent years. Initially, in 2020, the fink-client was only a wrapper around the Kafka consumer API to simplify the work of astronomers and other users performing follow-up with the Fink/ZTF Livestream service. In 2023 the client was expanded to support the Data Transfer service, and in 2025 support for the ZTF Xmatch service was added. Neither its core nor its interface changed much during that time.

With the start of LSST, the number of client connections and the need to access additional services grew quickly. For that reason we completely redesigned the CLI in version 12, and added two more services: bots (an extension of the Livestream) and search (a wrapper around the REST API). We hope you enjoy it!

Installation of fink-client

You would simply install the latest version of the client using pip in your terminal:

pip install fink-client --upgrade

Check the client is correctly installed by running:

finkctl

You should see the help menu, together with the version of the client.

Authentication

For some services, such as the Data Transfer and the Livestream, you must register before polling data. Please refer to the "Registration" section in the fink-client GitHub repository.

Migration from version 11 to 12

Migration from version 11 to 12

If you are coming from the client version 11, you will need a few changes for the client to work again.

Authentication

We recommend that you run again the authentication as the configuration files slightly changed. For this, just remove your current configuration, and authenticate again:

# backup old configuration
cp -r ~/.finkclient ~/.finkclient_$(date +%Y%m%d)

# Remove old configuration
rm -r ~/.finkclient

# Authenticate again
finkctl auth register ...

In case you are unsure about the parameters to fill, you can access the documentation by running:

finkctl auth register

and you can also display the current configuration by running:

finkctl auth show -survey lsst

Commands mapping

In version 12, the old commands have been replaced:

  • fink_client_register --> finkctl auth register
  • fink_consumer --> finkctl stream
  • fink_datatransfer --> finkctl transfer

Options to these commands remain the same!

Subscribe to topics

The topic management changed a lot with version 12. First, you can easily list the available topics for a survey using:

finkctl topic list -survey lsst

Once you identify a topic of interest, just subscribe using:

finkctl topic subscribe -survey lsst -name <topic name>

You can check your subscription at any time using:

finkctl auth show -survey lsst

How-to

How to register?

Based on the information sent when you asked for credentials, authenticate using the auth command:

finkctl auth register ...

In case you are unsure about the parameters to fill, you can access the documentation by running:

finkctl auth register

and you can also display the current configuration by running:

finkctl auth show -survey lsst

How to get data from the Data Transfer service?

Documentation for using the Data Transfer and polling data with the fink-client is available in the Data Transfer section.

How to know available topics for the Livestream service?

For the list of available topics (aka tags), see the schema page https://lsst.fink-portal.org/schemas . From version 12, you can also access this list programmatically:

finkctl topic list -survey lsst

How to connect to an alert topic produced by Fink?

Documentation for polling data from the Livestream with the fink-client is available in the Livestream section.

How to create a Fink bot for my alert topic?

Documentation for creating and running Fink bots with the fink-client is available in the Fink bots section.