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Triggers

OpenFaaS functions can be triggered easily by any kind of event. A small piece of code will convert from the event-source and trigger the function using the OpenFaaS Gateway API.

The most common use-case is HTTP which acts as a lingua franca between internet-connected systems.

Looking to trigger a function on a schedule? Have a look at the Cron page for more information

HTTP / webhooks

This is the default, and standard method for interacting with your Functions.

The function URL follows the pattern of:

https://<gateway URL>:<port>/function/<function name>

There is also the ability to execute a function asynchronously by replacing /function/ with /async-function/ before the function name

CLI

Trigger a function using the faas-cli by using the function name

echo "triggered" | faas-cli invoke figlet

CLI invocation can also be async by passing the -a flag to the invoke call

Other Event Sources

Event-connector pattern

The OpenFaaS connector-pattern allows you to create a broker or separate microservice which maps functions to topics and invokes functions via the OpenFaaS Gateway meaning that the OpenFaaS code does not need to be modified per trigger/event-source.

Add your own event source

If you'd like to add an event source which is not listed below you can fork the OpenFaaS event connector SDK which is written in Go and use this to connect your pub/sub topics or message queues to functions in OpenFaaS.

Apache Kafka

Connect your function(s) to Apache Kafka topics.

More information in the Incubator repository: openfaas-incubator/kafka-connector

Support is available for OpenFaaS Gateways using Basic Authentication.

AWS SNS

You can use AWS SNS to trigger functions using AWS SNS Notifications and Subscriptions. This approach can be used to export almost any data-source or event from your Amazon Web Services (AWS) console such as S3 of DynamoDB to an OpenFaaS function.

Find more information in the following repository: affix/OpenFaaS-SNS

Minio / S3

You can trigger OpenFaaS functions using Minio's webhook or Kafka integration.

CloudEvents

CloudEvents is a specification for describing event data in a common way.

Follow this example to learn how to trigger functions using the Azure EventGrid and CloudEvents.

More information in the repository: johnmccabe/cloudevents-slack-demo

IFTTT

You can trigger OpenFaaS functions using webhooks sent via the (if this, then that) service.

An example may be triggering a function which forwards Tweets about your brand or project to a given Slack channel. For this combination use the "Twitter search" Applet and have it trigger the "Make a web request" Applet giving the public URL of your OpenFaaS gateway and the receiver function such as https://gw.my-company.com/function/slack-forwarder

See an example of a function built to forward Tweets from IFTTTT to Slack using Golang: filter-tweets.

Visit ifttt.com to learn more.

Redis (third-party project)

Invoke functions using Redis pub/sub and the Sidekiq model.

View the sidekiq-connector

Note: the Redis connector currently has no support for gateways using Basic Authentication, but this is being worked on by the author.

RabbitMQ (third-party project)

Invoke functions from RabbitMQ topics

More information in the repository: Templum/rabbitmq-connector

Note: the RabbitMQ connector currently has no support for gateways using Basic Authentication, but this is being worked on by the author.