Istio vs. Linkerd: Service Mesh Showdown 2023

What is a Service mesh?

The use of Kubernetes to run workloads has become the standard in most organizations. While this has many advantages, it also introduces some challenges. One of the challenges is managing communication between services. Because Kubernetes abstracts away the visibility of the communication. This makes it difficult to troubleshoot problems and ensure that services are communicating.

Service mesh technologies offer a robust and effective solution to address that challenge. By adopting a sidecar approach, Service Mesh provides a centralized way of managing communication. This approach brings a wide range of features such as load balancing and observability to name a few. Two of the leading Service Mesh for Kubernetes are Istio and Linkerd. Both are graduate projects in the Cloud Native Computing Foundation (CNCF).

Other Open source Service mesh tools:

• Consul
• Open service mesh
• Network service mesh

These platforms offer a variety of features. They can help improve the reliability, performance, and security of microservices-based applications. They can also reduce the complexity of managing communication between services. Thus freeing up developers to focus on other tasks.

In this blog, I have conducted a comprehensive comparison of Istio and Linkerd. These two service mesh tools are being used by most organizations. This blog is to help DevOps professionals to understand the differences between Linkerd and Istio.

Istio

Google, IBM, and Lyft developed Istio in 2017. Istio is now managed by the Istio community, which is a group of volunteers who contribute to the project. Major companies like Amazon, and Netflix, now are using it in production. In July 2023, Istio achieved the status of graduate, showing maturity and stability.

Linkerd

Linkerd, a lightweight service mesh solution, is easy to use. Buoyant, a company founded by Kelsey Hightower and Joe Beda, developed it in 2015. In 2017, Buoyant donated Linkerd to the CNCF (Cloud Native Computing Foundation). On July 28, 2021, it achieved the status of a graduate project within the CNCF.

The Architecture

Istio and Linkerd have similar architecture. Both platforms use a two-part architecture: a control plane and a data plane. The control plane manages the data plane by issuing configuration updates to the proxies in the data plane. The control plane also provides security features such as mTLS encryption and authentication.

The data plane handles communication between services. It does this by deploying a proxy alongside each service.

Istio Architecture

Control Plane

The Istio control plane consists of the following components:

• Pilot: The Pilot component handles routing traffic between services.
• Galley: The Galley component handles storing and managing configuration data.
• Citadel: The Citadel component handles issuing and managing TLS certificates.
• Istiod: The Istiod component is the central control plane component in Istio. It provides a single point of contact for all other components in the control plane. It also provides a REST API for managing the service mesh.

Data Plane

Istio employs the Envoy proxies, deploying them alongside each service in the service mesh. It’s coded in C++, which exposes it to memory-related security vulnerabilities. Unlike Linkerd-2, Envoy stands as a more mature proxy. It has a boasting wider adoption among organizations.

Linkerd Architecture

Control Plane

The Linkerd control plane consists of the following components:

• Destination service: It handles and manages the configuration of the Linkerd proxies.
• Identity services: It handles issuing and managing TLS certificates for the service mesh.
• Proxy injector: The Proxy injector injects the Linkerd proxies into the services.

Data plane

The Linkerd-2 proxies deploy alongside each service in the service mesh. It’s developed in Rust which avoids the entire class of memory-related CVEs. It’s done through its advanced memory management. It is more lightweight compared to the envoy-proxy.

Traffic Management

Proxy Functionality:

Istio utilizes the Envoy proxy, providing comprehensive HTTP-specific features. These include native support for HTTP/1.1, WebSockets, HTTP/2, and HTTP/3. While Linkerd employs a micro-proxy, which lacks support for HTTP/3. This makes it less versatile in handling certain HTTP-specific functionalities.

Environment Support:

Istio stands out when it comes to supporting a wider range of environments. These may include Kubernetes (on-premises and managed). Also the public cloud platforms like AWS, GCP, Azure, and on-premises VMs. Linkerd’s environment support is more limited in comparison. This makes Istio the preferred choice in cloud-native applications, monoliths, and legacy workloads.

Ingress:

Istio incorporates Envoy as the ingress. This provides a powerful and feature-rich solution for managing ingress traffic. It supports features like load balancing, retries, and circuit breaking.

Linkerd does not have its own built-in ingress controller. This will need deployments of third-party controllers like NGINX to enable certain features. This step can add complexity to configuring ingress traffic in Linkerd.

Egress:

Istio manages egress traffic using virtual service objects and gateways. It offers straightforward control over routing to different services.

Linkerd lacks a built-in way to control egress traffic and requires the use of DNS and delegation tables (DTAB). This can be more complex compared to Istio’s approach.

Security Features

Linkerd

• Mutual TLS (mTLS): Linkerd supports mTLS by default for all TCP connections.
• JWT-based authentication: Linkerd also supports JWT-based authentication. This allows you to authenticate users and services using JSON Web Tokens.
• Security policies. Linkerd allows you to create security policies to control access to your microservices. These policies are based on factors such as the user’s identity, the service’s role, or the source IP address.

Istio

• Mutual TLS (mTLS): Istio supports mTLS for both HTTP and TCP connections.
• Federal Information Security Modernization Compliance. Istio adheres to FIPS regulations and contains some components that are FIPS compliant. This makes Istio an excellent choice for organizations with strict security standards. Additionally, Istio contributes its CVE information to the National CVE database. This streamlines the process for developers to remain informed about patches and releases.
• Flexibility in authentication. Istio offers flexibility by integrating with various authentication providers. These include OpenID Connect providers like OAuth. This makes it easy to integrate with the authentication method that suits your security requirements.

Scalability and Resource Efficiency

When choosing a service mesh, one of the most important factors to consider is scalability. How well will the service mesh scale as your application grows?

Linkerd

In recent years Linkerd has demonstrated remarkable resource efficiency. This also includes utilizing less CPU and memory compared to Istio. This performance allows Linkerd to scale and manage larger workloads without performance issues. Linkerd’s impressive speed also results in lower latency. This ensures a better experience for users and customers.

Istio

Istio is a more heavyweight service mesh compared to Linkerd. As a consequence, Istio’s scalability is not as robust. Istio is also found to consume more CPU and memory than Linkerd. This limits its ability to handle large workloads. Also, Istio introduces more latency compared to Linkerd, affecting its performance.

Visibility and Observability

Observability plays a vital role in managing service mesh. They ensure network health and application performance. Both Linkerd and Istio offer monitoring capabilities. They generate metrics such as latency, errors, and saturation for HTTP and gRPC traffic. Users can access the monitoring data through Grafana dashboards or web-based dashboard solutions.

Monitoring:

With Linkerd, monitoring becomes effortless with the deployment of “viz” (Linkerd-viz). It is a monitoring application based on Prometheus and Grafana. It’s autoconfigured to collect metrics from Linkerd, offering insights into service communication.

In the case of Istio, monitoring involves deploying Prometheus and Grafana. Also, you have to configure it with Kiali, this requires some initial configuration. But this solution delivers a robust monitoring solution for Istio. IMESH also delivers an intuitive UI designed for Istio.

Logging

Both Istio and Linkerd offer integration with standard Kubernetes logging stacks. This makes it easy for users to log network activity and policy violations. It supports popular tools such as ELK and Loki to centralize and analyze logs.

Tracing

Istio and Linkerd have similar approaches. Istio supports tracing backends like Jaeger’s, Zipkin, and SolarWinds. While Linkerd supports the same apart from Solarwind.

Community support and Popularity

Both Linkerd and Istio are mature projects. They are now graduates of the CNCF. This indicates a high level of stability and adoption within the industry. But when it comes to community support and popularity, there are some differences.

GitHub Stars:

On GitHub, Istio stands out with 33.4k stars. Making it more popular among developers. Linkerd has garnered 12.2k stars. The community at Linkerd is large but not compared to Istio.

Community Forums:

Both projects have active community forums. Users can seek help, share knowledge, and discuss ideas. Istio’s forum boasts over 20k members, showing a large and thriving community. In contrast, Linkerd’s forum has over 10k members. This indicates that Linkerd has a smaller but still engaged user base.

Use Cases and Recommendations

Istio Use Cases:

Istio shines in large-scale, complex microservices architectures. That demands advanced traffic management, security, and observability features. Projects with many deployment versions and canary releases enjoy Istio’s powerful traffic routing.

Linkerd Use Cases:

Linkerd is a good choice for projects seeking a lightweight, easy-to-adopt service mesh. It is well-suited for resource-constrained environments. It shines in scenarios where rapid setup and straightforward request routing are essential.

Conclusion

In conclusion, Istio and Linkerd are strong contenders in the service mesh landscape. They offer unique features and advantages. The choice between the two depends on your project’s specific requirements. These can be performance needs, scalability, and the complexity of your microservices architecture. Each tool brings its own set of strengths to the table. They are both worth exploring to determine which fits your microservices communication. Regardless of which service mesh you choose, embracing these technologies is crucial for modern microservices architectures. Because they enhance the observability, security, and performance of your services.