KrakenD framework joins the Linux Foundation. Read more.

Community docs (current)

Recent changes

Using publisher/subscribe as backends

Using publisher/subscribe as backends

Since KrakenD 1.0 you can connect an endpoint to multiple publish/subscribe backends, helping you integrate with event driven architectures. For instance, a frontend client can push events to a queue using a REST interface. Or a client could consume a REST endpoint that is plugged to the last events pushed in a backend. You can even validate messages and formats as all the KrakenD available middleware can be used. The list of supported backend technologies is:

  • AWS SNS (Simple Notification Service) and SQS (Simple Queueing Service)
  • Azure Service Bus Topic and Subscription
  • GCP PubSub
  • NATS.io
  • RabbitMQ
  • Apache Kafka

Configuration

To add pub/sub functionality to your backends include the namespaces github.com/devopsfaith/krakend-pubsub/subscriber and github.com/devopsfaith/krakend-pubsub/publisher under the extra_config of your backend section.

The host key defines the desired driver, and the actual host is usually set in an environment variable outside of KrakenD:

For a subscriber:

"host": "schema://",
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "url"
	}
}

For a publisher:

"host": "schema://",
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/publisher": {
        "topic_url": "url"
	}
}

See the specification of each individual technology.

Example (RabbitMQ):

Set the envvar RABBIT_SERVER_URL='guest:guest@localhost:5672' and add in the configuration:

"host": ["amqp://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
	"subscription_url": "myexchange"
	}
},

GCP PubSub

Google’s Cloud Pub/Sub is a fully-managed real-time messaging service that allows you to send and receive messages between independent applications.

The configuration you need to use is:

  • host: gcppubsub://
  • url for topics: "projects/myproject/topics/mytopic" or the shortened form "myproject/mytopic"
  • url for subscriptions: "projects/myproject/subscriptions/mysub" or the shortened form "myproject/mysub"
  • Environment variables: GOOGLE_APPLICATION_CREDENTIALS, see Google documentation.

Example:

"host": ["gcppubsub://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
	"subscription_url": "projects/myproject/subscriptions/mysub"
	}
},

NATS

NATS.io is a simple, secure and high performance open source messaging system for cloud native applications, IoT messaging, and microservices architectures.

Configuration:

  • host: nats://
  • Environment variable: NATS_SERVER_URL
  • url: mysubject

No query parameters are supported.

Example:

"host": ["nats://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "mysubject"
	}
}

AWS SNS

Amazon Simple Notification Service (SNS) is a highly available, durable, secure, fully managed pub/sub messaging service that enables you to decouple microservices, distributed systems, and serverless applications. Amazon SNS provides topics for high-throughput, push-based, many-to-many messaging

AWS SNS sets the url without any host or environment variables, e.g:

"host": ["awssns:///arn:aws:sns:us-east-2:123456789012:mytopic""],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "?region=us-east-2"
	}
}

AWS SQS

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.

AWS SQS sets the url without any host or environment variables, e.g:

Url: awssqs://sqs-queue-url

"host": ["awssqs://https://sqs.us-east-2.amazonaws.com/123456789012"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "/myqueue?region=us-east-2"
	}
}

Azure Service Bus Topic and Subscription

Microsoft Azure Service Bus supports a set of cloud-based, message-oriented middleware technologies including reliable message queuing and durable publish/subscribe messaging. These “brokered” messaging capabilities can be thought of as decoupled messaging features that support publish-subscribe, temporal decoupling, and load balancing scenarios using the Service Bus messaging workload.

Configuration:

  • host: azuresb://
  • Environment variable: SERVICEBUS_CONNECTION_STRING
  • Topics: mytopic
  • Subscriptions: mytopic?subscription=mysubscription

Note that for subscriptions, the subscription name must be provided in the ?subscription= query parameter.

Example:

"host": ["azuresb://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "mytopic"
	}
}

RabbitMQ

RabbitMQ is one of the most popular open source message brokers.

Rabbit can alternatively be configured using the AMQP component.

Configuration:

  • host: rabbit://
  • Environment variable: RABBIT_SERVER_URL
  • url for topics: myexchange
  • url for subscriptions: myqueue

No query parameters are supported.

Example:

"host": ["rabbit://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "myexchange"
	}
}

Kafka

Apache Kafka is a distributed streaming platform.

Kafka connection requires KrakenD >= 1.1.

  • host: kafka://
  • Environment var: KAFKA_BROKERS pointing to the server(s), e.g: KAFKA_BROKERS=192.168.1.100:9092

Kafka subscriptions:

"host": ["kafka://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/subscriber": {
        "subscription_url": "group?topic=mytopic"
	}
}

Kafka topics:

"host": ["kafka://"],
"disable_host_sanitize": true,
"extra_config": {
	"github.com/devopsfaith/krakend-pubsub/publisher": {
        "topic_url": "mytopic"
	}
}

Unresolved issues?

The documentation is only a piece of the help you can get! Whether you are looking for Open Source or Enterprise support, see more support channels that can help you.

We use cookies to understand how you use our site and to improve your overall experience. By continuing to use our site, you accept our Privacy Policy. More information