pubsub

Getting started

Works like Gin but for events

package main

import (
	"github.com/sirupsen/logrus"

	"gitlab.wheniwork.com/go/pubsub"
	"gitlab.wheniwork.com/go/pubsub/hooks"
	"gitlab.wheniwork.com/go/pubsub/middleware"
	"gitlab.wheniwork.com/go/pubsub/plugins/retry"
	"gitlab.wheniwork.com/go/pubsub/providers/kafka"
)

const (
	serviceName               = "pubsub"
	awsRegion                 = "us-east-1"
	retryEventTopic           = "pubsub-retry-events"
	deadLetterEventTopic      = "pubsub-dead-letter-events"
	maxRetryAttempts     uint = 5
)

func main() {
	var brokers []string
	var log logrus.FieldLogger

	kafkaProv, err := kafka.NewProvider(brokers, serviceName, awsRegion)
	if err != nil {
		// ...
	}

	// Create a new pubsub service
	pubsubService := pubsub.New(
		kafkaProv,
		pubsub.WithLog(log),
		pubsub.WithMiddlewares(
			middleware.Logrus(log),
			middleware.Recover(nil),
		),
		pubsub.WithPlugin(retry.NewPlugin(retryEventTopic, deadLetterEventTopic, maxRetryAttempts)),
	)

	// Subscribe for messages/events
	pubsubService.Subscribe("topic", func(ctx *pubsub.Context) error {
		// ...
		return nil
	})

	// Publish a message/event
	err = pubsubService.Publish("topic", "any", pubsub.NewKey)
	if err != nil {
		// ...
	}

	// ... a few lines later ...

	err = pubsubService.Stop()
	if err != nil {
		// ...
	}
}

Troubleshooting

Why am I not receiving any events?

1. Has the topic been created in Kafka?
   On our local development environments these are created automatically when a message is published to a topic that doesn't exist.
   For any other env you'll need to have them added manually. https://wheniwork.atlassian.net/browse/DEV2-536.
2. Have you added publisher/consumer permissions in IAM?
   This MR is a good example of what's needed. https://gitlab.wheniwork.com/devops/terraform/resource/application-aws-iam-role/-/merge_requests/138/diffs
   Don't forget to add the various topics you're using.
3. I've added everything but I'm still not getting messages through!
   Make sure your configured topics and the topics created in Kafka match. A simple typo can really mess things up and become really hard to debug. Important! For some reason the segmentio reader will fail reading for all topics even if only one of them is incorrect.