Instructions

Example app composed by a rabbitmq message broker instance and two golang apps: a message publisher and a message consumer. The example is meant to show how the publisher application can create its own exchange (a notification channel) and publish its messages on this exchange. At the same time there can be more than 1 consumer applications: each consumer creates its own queue subscribing it to the exchange. The queues receive a copy of each one of the messages in the subscribed exchange so this system can perfectly work as a Pub/Sub system.

In the example is explained how to start the apps using either Minikube (k8s) and Golang and Docker.

Using Minikube

• Go to Katacoda Minikube environment:

• Start minikube with: minikube start

• Clone the Github project

• enter the folder cd rabbit-go

Publish docker images of the two services: publisher and consumer

You can skip this step if the images are already present to the public repository of Dockerhub according to the name specified in the yaml files.

# docker login
docker login -u=<username-here> -p=<password-here>

# create publisher image and push it on DockerHub
cd publisher
docker build -f Dockerfile -t alessandroargentieri/rabbit-go-publisher .
docker push alessandroargentieri/rabbit-go-publisher
cd ..

# create consumer image and push it on DockerHub
cd consumer
docker build -f Dockerfile -t alessandroargentieri/rabbit-go-consumer .
docker push alessandroargentieri/rabbit-go-consumer
cd ..

Create k8s secret for the rabbitmq credentials

# create secret
kubectl create secret generic rabbit-credentials --from-literal=password=password --from-literal=user=myuser

# get yaml of the created secret
kubectl get secret rabbit-credentials -o yaml

Deploy yaml to k8s

kubectl apply -f k8s/yamls/rabbit.yaml
kubectl apply -f k8s/yamls/publisher.yaml
kubectl apply -f k8s/yamls/consumer.yaml

Get the NodePort addresses

# copy the addresses for the publisher nodeport and the consumer nodeport
minikube service list

Call the publisher service through its NodePort service (on port 32000)

curl http://<publisher-copied-ip>:32000/publisher | jq

Call the consumer service through its NodePort service (on port 32100)

curl http://<consumer-copied-ip>:32100/consumer | jq

---

Using Go and Docker

• Go to Katacoda Ubuntu environment:

• Clone the Github project

• enter the folder cd rabbit-go

• start everything with the script ./init.sh

Call the publisher service

curl http://localhost:8080/publisher | jq

Call the consumer services

curl http://localhost:8081/consumer | jq
curl http://localhost:8082/consumer | jq
curl http://localhost:8083/consumer | jq

Check the logs in the log files saved locally

# open the producer log file
tail -f publisher-logs.txt

# Ctrl+C

# open the consumer-1 log file
tail -f consumer-1-logs.txt

# Ctrl+C

# open the consumer-2 log file
tail -f consumer-1-logs.txt

# Ctrl+C

# open the consumer-3 log file
tail -f consumer-1-logs.txt

# Ctrl+C