The Kisi Backend Code Challenge

This repository can be used as a starting point for the Kisi Backend Code Challenge. Feel free to replace this README.md with your own when you submit your solution.

This repository contains:

• A bare-bones Rails 6 API app with a Gemfile that contains the neccessary libraries for the project.
• A configured adapter (lib/active_job/queue_adapters/pubsub_adapter.rb) to enqueue jobs. Use as a starting point for your own code.
• A rake task (lib/tasks/worker.rake) to launch the worker process. Use as a starting point for your own code.
• A class (lib/pubsub.rb) that wraps the GCP Pub/Sub client. Use as as a starting point for your own code.
• A Dockerfile and a docker-compose.yml configured to spin up necessary services (web server, worker, pub/sub emulator).

Pubsub

Google Cloud Pub/Sub adapter and worker for ActiveJob

Configuration

Adapter

First, change the ActiveJob backend.

Rails.application.config.active_job.queue_adapter = :pubsub

Usage

To boot up the background jobs server, you first need to export your google cloud configuration file to your environment:

$ export GOOGLE_APPLICATION_CREDENTIALS=/path/to/config/file

Note: The Google cloud entity(service account, user, e.t.c) in the config must have top-level permissions for google pub/sub (owner or admin). He/She/It should be able to read/delete/create Pub/Sub resources).

With that ActiveJob would use the pubsueque adapter to enqueue jobs to Google pub/sub and execute them immediately or at a specified time.

  class HelloJob < ActiveJob::Base
        def perform(args)
            // job
        end
    end

    HelloJob.perform_later(args) # enqueue the job to pub/sub and execute in the background immediately (after the pub/sub subscriber receives the job).
    HelloJob.set(wait_until: 10.minutes).perform_later(args) # enqueue the job to pub/sub and execute in 10 minutes.

Rake task

The rake task can be run from the command line using the following command. This task pulls messages from GCP Pub/Sub and executes the corresponding job.

  bundle exec rake worker:run

Enqueue a Job

 HelloJob.perform_later(args) # enqueue the job to pub/sub and execute in the background immediately (after the pub/sub subscriber receives the job).
 HelloJob.set(wait_until: 10.minutes).perform_later(args) # enqueue the job to pub/sub and execute in 10 minutes.

Testing

Using Docker

To start all services, make sure you have Docker installed and run:

$ docker compose up

To restart the worker, i.e. after a code change:

$ docker compose restart worker

To start a console:

$ docker compose run --rm web bin/rails console

If you run docker with a VM (e.g. Docker Desktop for Mac) we recommend you allocate at least 2GB Memory

Using Pub/Sub emulator

In order to test the worker in your local environment, it is a good idea to use the Pub/Sub emulator provided by gcloud command. Refer to thisdocument for the installation procedure.

$ gcloud beta emulators pubsub start --project=PUBSUB_PROJECT_ID  #starts the emulator

(Switch to another terminal)

$(gcloud beta emulators pubsub env-init) #setting environment variables

To use the emulator, you must have an application built using the Cloud Client Libraries