Reliable does not mean "to fail never", but it means to be able to recover from failures. How to handle reliability change in the k8s world?

1. Sviluppare applicazione 'reliable'
con .net core e AKS
Alessandro Melchiori // @amelchiori

2. What does “reliable” mean?
Reliable applications are:
● Resilient and recover gracefully from failures, and they continue to
function with minimal downtime and data loss before full recovery.
● Highly available (HA) and run as designed in a healthy state with no
significant downtime.

3. What does “reliable” mean?
Reliable applications are:
● Resilient and recover gracefully from failures, and they continue to
function with minimal downtime and data loss before full recovery.
● Highly available (HA) and run as designed in a healthy state with no
significant downtime.

4. What does “reliable” mean?
Instead of trying to prevent failures altogether, the goal is
to minimize the effects of a single failing component.

5. With the network of microservices - service-to-service
communication can become challenging

6. /api/values
/api/values/detailed

8. /api/values
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9. /api/values
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10. /api/values
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11. /api/values
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12. DEMO

13. AND NOW?

14. Circuit breaker

15. Circuit breaker
/api/values
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16. Transient errors: retry pattern
/api/values
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17. Transient errors: retry pattern
/api/values
/api/values/detailed

18. Welcome
Polly

19. Welcome Polly
Polly is a .NET resilience and transient-fault-
handling library that allows developers to
express policies such as Retry, Circuit Breaker,
Timeout, Bulkhead Isolation, and Fallback in a
fluent and thread-safe manner.

20. DEMO

21. Welcome
Kubernetes

22. Pod overview
● Is the basic building block of Kubernetes
● Represents a running process on the
cluster
● Consists of either a single container or a
small number of containers that are
tightly coupled and that share resources

23. Pod overview
● Is the basic building block of Kubernetes
● Represents a running process on the
cluster
● Consists of either a single container or a
small number of containers that are
tightly coupled and that share resources

24. Sidecar pattern
The sidecar pattern consists of a main
application plus a helper container with
a responsibility that is essential to your
application, but is not necessarily part of
the application itself.
The most common sidecar containers
are logging utilities, sync services,
watchers, and monitoring agents.

25. Traefik
An open-source reverse proxy and load balancer for
HTTP and TCP-based applications that is easy, dynamic,
automatic, fast, full-featured, production proven,
provides metrics, and integrates with every major cluster
technology... No wonder it's so popular!

26. svc svc

27. DEMO (K8s pod multicontainer config)

28. Traefik middleware

29. Traefik circuit breaker
# Latency Check
[http.middlewares]
[http.middlewares.latency-check.circuitBreaker]
expression = "LatencyAtQuantileMS(50.0) > 100"

30. Others Traefik middlewares
● RateLimit:
The RateLimit middleware ensures that services will receive a fair number
of requests, and allows you define what is fair
● Retry:
The Retry middleware is in charge of reissuing a request a given number of
times to a backend server if that server does not reply.

31. Cross-cutting concerns
● Logs
● Metrics
○ Datadog
○ InfluxDB
○ Prometheus
○ StatsD
● Tracing: the tracing system allows developers to visualize call flows in their
infrastructure.
○ Zipkin
○ Datadog
○ Instana
○ ...

32. Alessandro Melchiori
Software developer @ CodicePlastico
alessandro@codiceplastico.com
@amelchiori