Prepare for Istio Certification: Resiliency, Fault Injection, Security, and Advanced Scenarios

To help our community better prepare for Istio certification, we recently streamed five sessions covered in the curriculum in an event we called Mesh Week.

In part 1 of our Mesh Week recap, we delved into Istio installation, upgrade, and configuration, as well as Istio traffic management. In part 2, we explore Istio resiliency and fault injection, security and securing workloads, and advanced scenarios you might encounter.

Istio Resiliency and Fault Injection

In this session, we covered the resiliency and failure injection features in Istio, such as timeouts, retries, and circuit breakers.

• Timeouts set a maximum duration for a request to be processed. If the request exceeds the specified timeout, it is considered failed. This helps prevent resources from being tied up indefinitely and allows for better resource allocation.
• Retries allow for automatic retries of failed requests. Istio configures two retries for service by default, but we can change that to a different value in VirtualService. Setting retries is a good practice that helps handle transient failures and improves the system’s overall reliability.
• Circuit breakers are used to prevent cascading failures in a distributed system. They monitor the health of services and can temporarily stop sending requests to a service experiencing issues. This helps isolate failures and prevents them from affecting other services.

While timeouts, retries, and failure injection can be configured in the VirtualService resource, the circuit breakers are configured in the DestinationRule.

Fault injection allows us to inject arbitrary failures such as delays or aborts (specific HTTP status codes) to simulate real-world networks.

Security in Istio and Securing Workloads

Security topics in the Istio Certified Associate exam account for 20% of the exam score. In this session, we covered the Istio security features, talked about mutual TLS, and explained how to configure authorization policies.

• X.509 certificates are issued to each workload in the mesh and are used as part of the service identity, which is encoded in the SAN field of the X.509 certificate as a URL (e.g., spiffe://example.org/ns/default/workload).
• Certificates are automatically issued and managed (e.g., refreshed) by Istiod.
• Envoy proxies perform mutual TLS handshake and verify the service identities.
• Istio uses a permissive mode for service-to-service communication and allows both mTLS and plain text communication.
• PeerAuthentication is used to configure the mTLS mode across the mesh, namespace, or workloads; it configures mTLS settings for inbound traffic, while DestinationRule can configure TLS settings for outbound traffic.
• AuthorizationPolicy uses the service (peer) or user principals and allows us to write authorization rules.

The “Understanding TLS Configuration” documentation is a must-read to understand how TLS settings are reconfigured for various connections involved when sending requests in Istio.

Advanced Scenarios and Troubleshooting Istio

In this video, we discussed advanced scenarios and troubleshooting in Istio. We covered topics such as bringing VM workloads into the mesh, connecting multiple clusters, and using EnvoyFilter resources to control the Envoy proxy configuration.

The key to mastering this exam section is understanding Envoy’s basic building blocks. Then, you can use Istio CLI to troubleshoot and review the Envoy configuration (e.g., istioctl proxy-config command).

We hope this overview helps you feel better prepared to take the Istio Certification exam. Learn even more about Istio by taking our courses through Solo Academy.