Microservices

March 28, 2022 ยท View on GitHub

Composition

Service Interaction

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Technology

  1. PostgreSQL;
  2. Django;
  3. DRF;
  4. RabbitMQ;
  5. health-check;
  6. CI/CD;
  7. Pattern DRY, Circuit Breaker.

General configuration

All services have health checks:

curl https://self-service-app.herokuapp.com/manage/health
{
  "status": "Work",
    components: {
      "db": {
      "status": "Work",
      "name": "store",
      "database": "PostgreSQL"
      },
      "ping": {
        "status": "work"
      },
      "time": {
        "epoch": 1603933252,
        "local": "2020-10-29T01:00:52.658050+00:00",
        offset: 0.4
      }
   }
}

System fault tolerance

Implemented mechanisms that increase the fault tolerance of the system.

  1. In case of unavailability of part of the systems or internal server errors, we return an error with an explanation (i.e. HTTP status 4xx or 5xx + json with explanation).

  2. Implemented validation of input data. If the data is not in the correct format, return 400 Bad Request. It mainly concerns the POST method. The data is validated using regular expressions.

  3. Implemented Circuit Breaker pattern. The circuitbreaker library is responsible for this. Accumulate statistics (in memory), and if the system did not answer 3 times, then together

  4. On the Store Service system:

    • For an aggregating read request (request #1 and #2), if one of the systems is unavailable, we perform degradation functionality.
    • For the purchase and return operation (request #4 and #5) in case one of the systems is unavailable perform a full rollback of the operation.
    • To request a warranty on an order, if the Warranty Service is not available, we return a successful result, and the operation is queued for re-execution. When the system available during the operation is raised, the operation must be performed. For the queue we use RabbitMQ, on Heroku we connect via add-ons.