What Is Istio?
Istio is a service mesh platform that enables developers to connect, secure, control, monitor, and run distributed microservices architectures. It is open source and supports any language, platform, or operating environment. Istio manages service interactions for both container- and virtual machine (VM)-based workloads.
Traditionally, developers solved problems in distributed systems by modifying application code or using language-specific client libraries. However, this was not a scalable approach. Istio helps developers overcome the loss of observability and control as the number of microservices increases, acting as an infrastructure layer that sits between application services and the network. Thus, it provides a unified control plane for microservices monitoring and management.
Reasons You Need Istio in Your Kubernetes Clusters
1. Traffic Management
The traffic routing rules in Istio enable easy control over API calls, and traffic flows between services. Istio helps simplify the configuration of various service-level properties, including timeouts, retries, and circuit breakers. It makes setting up critical tasks easier, including canary deployments, A/B testing, and staged rollouts with traffic splits.
Istio also offers out-of-box reliability capabilities to make applications more resilient against network failures or issues with dependent services. The Istio traffic management model uses Envoy proxies deployed alongside the services. All data plan traffic (received and sent by the mesh services) goes through Envoy—it is easy to control and direct mesh traffic without modifying any services.
Istio must know the location of all endpoints and their associated services to direct traffic. Istio uses an external service discovery solution to populate its service registry. For instance, if Istio is installed on a given Kubernetes cluster, Istio will automatically detect the endpoints and services and endpoints in the cluster.
In addition to providing a functional service mesh with load balancing and service discovery features, Istio offers more granular control over mesh traffic. For example, it can direct a specified percentage of traffic to a different version of a specific service (i.e., for A/B testing) or apply different traffic load balancing policies to select service instances. Admins can apply unique rules to mesh or add external dependencies to the service registry by adding custom configurations via the Istio traffic management API.
Splitting a monolithic application into multiple services offers several advantages, such as scalability, agility, and reusability. Containers have unique security considerations:
- Service-based architectures require traffic encryption to prevent man-in-the-middle (MitM) attacks.
- Flexible and robust access control requires granular service access policies and mutual TLS.
- Auditing tools are necessary to track what entity carried out each action and when.
Istio Security offers comprehensive security capabilities to address external and internal threats to platforms, endpoints, data, and communications. These security capabilities provide robust access policies, identity management, TLS encryption, and tools to facilitate authentication, authorization, and auditing.
Istio helps protect data and services with the following security principles:
- Security by default—no need to change application infrastructure or code.
- Defense in depth—integration with other security tools to provide multiple layers of protection.
- Zero trust networking—all network traffic is untrusted by default.
Istio can generate detailed telemetry data for all traffic within the service mesh. This data provides service behavior observability, allowing operators to optimize, troubleshoot, and maintain applications without additional burden on service developers. Istio gives operators full visibility into how the monitored services interact with other services as well as the actual Istio components.
Istio generates these types of telemetry data to enable observability across the service mesh:
- Service metrics based on four monitoring golden signals (latency, traffic, saturation, and errors). Istio generates detailed metrics for mesh control planes. A basic set of monitoring dashboards to display these metrics are also provided.
- Distributed traces with trace scopes for each service, giving operators detailed visibility into service dependencies and call flows within the mesh.
- Access logs that track traffic flowing into services within the mesh. Istio can create a complete record of every request that includes metadata about the source and destination. Operators can use these logs to audit each service’s behavior at the workload instance level.
3. Strong Support for Multi-cloud
Istio is platform independent. This means that Kubernetes users can use Istio in container-based architectures, while designing other systems to run in VMs on a cloud platform. Istio can manage security, monitor issues, and control traffic between services in public cloud, local data center, or hybrid cloud environments.
4. Enhanced Microservices and Infrastructure Scalability
Istio supports microservices management because it can support virtually any scale. It also provides flow control between all microservices.
Istio decouples the proxy layer, which is responsible for properly distributing requests between services, from services themselves. It imports telemetry from sidecar containers and sends them to monitoring dashboards, allowing operators to improve infrastructure performance and reliability. Istio can withstand network outages, allowing the infrastructure to recover itself.
Istio on Kubernetes can help organizations build large-scale applications with many microservices. As application traffic increases, so does the volume of requests between these services, requiring advanced routing capabilities. This is important for optimizing data flow and ensuring continuous high performance of your application. Istio's service mesh allows developers to add value to each new service they create instead of having to manage how services are connected.
For DevOps teams, Istio makes it possible to programmatically deploy applications and infrastructure, allowing network and security settings to be managed as code.