Infrastructure design pattern with API, workers, message broker and database.

Scheme of microservice is following:

+--------+                                  +----------------------+
| User 1 | <--+                    +----+   |       +----------+   |     
+--------+    |    +-----+ <-----> | DB | <-+   +-> | Worker 1 | --+ 
              +--> | API |         +----+       |   +----------+   |                       
+--------+    |    +-----+ --+                  |                  |
| User 2 | <--+              |    +--------+    |   +----------+   |         
+--------+                   +--> | Broker | <--+-> | Worker 2 | --+                             
                                  +--------+        +----------+                  
                                                        ...

What is going on

At API, there are three endpoints:

• / - basic info
• /newTask - create new task and return its id, task is send to broker
• /tasks - list of all tasks, you can check status here

Worker consuming tasks queue. It took new or unprocessed message and do "something" (and updates task info).

In case of worker failure, its message is consumed by another worker.

Prequisities

• Terraform
• DigitalOcean account

Setup

Just go to /terraform folder and fill terraform.tfvars, then do these commands:

terraform init     # setup terraform plugins
terraform plan     # preview the changes to infrastructure
terraform apply    # build infrastructure
terraform destroy  # when you've seen enough