word_counter

Simple application to present basic concepts of CI/CD, orchestratrion, service discovery and load balancing.

Technologies

• Python 3 with Flask
• HashiCorp Nomad as the Orchestrator
• HashiCorp Consul as the Service Discovery
• Fabio LB as the Load Balancer
• Github as Docker image repository
• Docker
• Virtualenv
• Basic HTML

How to run the application

0. Install Docker on your server
1. Download Nomad https://www.nomadproject.io/downloads
2. Unzip the package and move the single binary to /usr/local/bin/nomad
3. Open a terminal and type: nomad agent -dev. One important note — in dev mode, Nomad will not persist any data. That’s fine for experimenting and prototyping, but not something you should do in production.
4. Open Nomad dashboard accessing http://localhost:4646
5. At Jobs section, click "Run Job" and paste the content of the file infra/consul.nomad
6. At Jobs section, click "Run Job" and paste the content of the file infra/fabio.nomad
7. At Jobs section, click "Run Job" and paste the content of the file infra/word_counter.nomad
8. Access http://localhost:9999 to access the word counter serice UI

How to monitor

• Access http://localhost:4646 to monitor the jobs being orchestrated
• Access http://localhost:8500 to monitor the services being discovered
• Access http://127.0.0.1:9998 to monitor the services being balanced

How to scaling up

1. Click on j-word-counter job at Nomad Dashboard and hit Stop
2. Access the file infra/word_counter.nomad and change scaling min max as needed
3. At Jobs section, click "Run Job" and paste the content of the file infra/word_counter.nomad

Considerations

• Some configurations are set to consider a debug or dev environment. At a production environment, some changes would be required.
• About CI/CD, the most important file is word_counter.yml, that is an Github Action and the Dockerfile.
• CI/CD and Github Actions is not the focus of this README.md, but were all implemented in the repository.
• Github as image repository requires some specific configurations that was not covered in this README.md