open-telemetry / opentelemetry-demo

Distributed System Design for open-telemetry/opentelemetry-demo

This documentation page provides an overview of the distributed system design principles and patterns used in the development of the open-telemetry/opentelemetry-demo project.

What is Distributed System Design?

Distributed system design refers to the process of creating and managing complex applications that are composed of multiple, interacting components. These components can run on different machines, and they communicate with each other over a network.

In the context of the open-telemetry/opentelemetry-demo project, the distributed system design includes the following components:

  1. Telemetry Collector: This component is responsible for collecting and aggregating telemetry data from various services. It uses OpenTelemetry to instrument the services and collect metrics, traces, and logs.
  2. Service Registry: This component is used for service discovery. It allows services to register themselves and makes their availability known to other components in the system.
  3. Load Balancer: This component distributes incoming network traffic across multiple instances of a service. It helps to ensure that no single instance is overwhelmed with requests.
  4. Circuit Breaker: This pattern helps to improve the resilience of the system by reducing the impact of failures. It allows a service to return an error response instead of trying to process a request that is likely to fail.

Why is Distributed System Design important?

Distributed system design is important because it allows us to build scalable, fault-tolerant, and resilient applications. By distributing the workload across multiple components, we can improve the performance and reliability of the system.

Additionally, distributed system design helps to improve the maintainability and testability of the application. Each component can be developed and tested independently, which makes it easier to make changes and fix bugs.

Service Discovery

The open-telemetry/opentelemetry-demo project uses a service registry for service discovery. The specific implementation used is Consul, an open-source tool for service discovery, configuration, and orchestration.

Consul allows services to register themselves and makes their availability known to other components in the system. It also provides a DNS-based service discovery mechanism, which makes it easy to look up the IP address of a service by its name.

Here’s an example of how to register a service with Consul:

package main
          
          import (
              "github.com/hashicorp/consul/agent"
          )
          
          func main() {
              err := agent.PlanAndRun("service", "my-service", nil)
              if err != nil {
                  panic(err)
              }
          }

Circuit Breakers

The open-telemetry/opentelemetry-demo project uses the Golang Resilience/Resilience package for implementing circuit breakers.

Circuit breakers help to improve the resilience of the system by reducing the impact of failures. They allow a service to return an error response instead of trying to process a request that is likely to fail.

Here’s an example of how to use the circuit breaker pattern with the Resilience package:

package main
          
          import (
              "github.com/resilience/resilience-golang/circuitbreaker"
              "github.com/resilience/resilience-golang/retry"
              "net/http"
          )
          
          func main() {
              cb := circuitbreaker.NewCircuitBreaker()
              r := retry.NewRetryer()
          
              client := &http.Client{
                  Timeout: time.Second * 10,
              }
          
              service := func(args *struct{}) error {
                  resp, err := client.Get("http://localhost:8080/")
                  if err != nil {
                      return err
                  }
                  defer resp.Body.Close()
          
                  if resp.StatusCode != http.StatusOK {
                      return fmt.Errorf("failed to get response from service: %s", resp.Status)
                  }
          
                  return nil
              }
          
              err := r.RetryN(context.Background(), func() error {
                  return cb.Call(context.Background(), service)
              })
              if err != nil {
                  log.Println("Error:", err)
              }
          }

Load Balancing

The open-telemetry/opentelemetry-demo project uses the Golang Net/HTTP package for load balancing.

Load balancing distributes incoming network traffic across multiple instances of a service. It helps to ensure that no single instance is overwhelmed with requests.

Here’s an example of how to use the Net/HTTP package for load balancing:

package main
          
          import (
              "fmt"
              "net/http"
          )
          
          type Backend struct {
              addr string
          }
          
          func (b *Backend) ServeHTTP(w http.ResponseWriter, r *http.Request) {
              fmt.Fprintf(w, "Hello, you've requested: %s\n", r.URL.Path)
          }
          
          func main() {
              backends := []*Backend{
                  {addr: "localhost:8081"},
                  {addr: "localhost:8082"},
                  {addr: "localhost:8083"},
              }
          
              http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
                  backend := backends[r.URL.Path[1:]%len(backends)]
                  http.Serve(w, backend)
              })
          
              http.ListenAndServe(":8080", nil)
          }

Sources: