Linkerd vs Istio

A 2021 service mesh comparison

Like many organizations, we considered Istio. But our research led to the conclusion that we would need a team of developers just to run it. It was too complicated, requiring ongoing, active attention—it’s not fire and forget. We looked at other solutions and ended up with a shortlist of half a dozen different options, but the one that stood out was Linkerd.” —When LeBron scores, latency matters: Realizing 10x throughput while driving down costs and sleeping through the night

We installed Linkerd and everything was just working right — we didn’t have to add any extra configurations or anything like that. With Istio, we would have had to make a bunch of changes to make everything work.“_ —Will Istio or Linkerd Dominate Service Mesh?

“We’ve felt encumbered by [Istio’s] complexity every time when configuring, maintaining or troubleshooting in our clusters. After yet another “Oh… This problem was caused by Istio!“-moment, we decided the time was ripe to consider the alternatives. We looked to the grand ol’ Internet for alternatives and fixed our gaze on the rising star Linkerd.“ —Changing service mesh: How we swapped Istio with Linkerd with hardly any downtime

The service mesh is here to stay, and Kubernetes adopters around the world are deciding between Istio and Linkerd. In 2021, engineers are increasingly choosing Linkerd. Why is that?

In this comparison, we’ll walk you through the similarities and differences between the projects and when to choose one over the other.

The big picture

Istio and Linkerd are both service meshes. The two projects have similar goals: to add reliability, security, and observability to Kubernetes applications. Both proejcts work by adding transparent “sidecar proxies” alongside application instances, and providing features by through these proxies.

Despite these similarities, the two projects couldn’t be more different. Istio is a “big vendor” project, with the complexity to match. Linkerd takes the opposite approach, focusing on simplicity (especially operational simplicity), performance, and user experience.

We’re biased, of course, but here’s our take on the comparison—including situations where you should choose Istio over Linkerd!

Why choose Linkerd over Istio?

In short, you should choose Linkerd if you are focused on Kubernetes and want a service mesh that gets out of your way. Unless you have a complex set of requirements that Linkerd simply can’t address, Linkerd will make your life easier. Why?

Linkerd is faster

Linkerd is significantly faster than Istio, meaning that your users and customers will experience better performance. In the project’s recent service mesh benchmarks, Linkerd added anywhere from 40% to 400% less latency than Istio did. Why is this? Linkerd’s state-of-the-art, ultralight Rust “micro-proxy” is designed just for the service mesh use case and can be highly optimized to handle this traffic.

Linkerd vs Istio benchmarks

Linkerd vs Istio latency

Linkerd is smaller

Linkerd consumed significantly fewer system resources than Istio, especially at the critical data plane level (which scales with your application). In the project’s recent service mesh benchmarks, Linkerd used an order of magnitude less CPU and memory than Istio. The primary reason? Again, Linkerd’s ultralight Rust “micro-proxy”, designed specifically for the service mesh usecase.

Under the hood of Linkerd's state-of-the-art Rust proxy

Linkerd vs Istio memory

Linkerd is more secure

Linkerd makes it easier to build secure systems. Linkerd’s configuration surface area is significantly smaller than that of Istio, and security features like mutual TLS are on by default. (In other words, the moment you install Linkerd, all communication between meshed pods is automatically encrypted and validated with mutual TLS, no configuration required!)

Istio uses the general-purpose Envoy proxy, which is built on C++, a legacy language known for its memory-related security vulnerabilities. By contrast, Linkerd’s data plane is built in Rust, a language that avoids the entire class of memory-related CVEs through advanced memory management. The Linkerd team believes that the future of the cloud will be built in Rust.

“One astonishing fact sticks out: the majority of vulnerabilities fixed and with a CVE assigned are caused by developers inadvertently inserting memory corruption bugs into their C and C++ code.” — Microsoft, A proactive approach to more secure code

Why Linkerd doesn't use Envoy

Linkerd is simpler

Linkerd’s core design philosophy is about minimalism: a service mesh should be simple, light, and secure, and do as little as possible to get the job done. Linkerd is especially focused on reducing operational complexity: the human toil involved in maintaining, operating, and being on-call for a production service mesh.

Istio takes a different approach and presents an all-in-one solution. Many features and configurations are supported, from built-in ingress controllers to multiple types of multi-cluster operations. This allows Istio to tackle a range of complex situations, but also means that Istio is extremely difficult to operate and configure.

Linkerd's design principles

Linkerd is the only graduated CNCF service mesh

Linkerd is a graduated project of the Cloud Native Computing Foundation, the same neutral foundation that hosts Kubernetes, Prometheus, and other core cloud native projects. Linkerd has publicly committed to open governance, has over 200+ contributors from all over the world, and a public steering committee of end users. Istio, by contrast, is not a CNCF project but is hosted in the OUC, a foundation that Google created specifically for it.

Announcing Linkerd's CNCF Graduation

Linkerd has a free cloud management dashboard

Linkerd users get free access to Buoyant Cloud, a hosted dashboard that allows you to share your Linkerd metrics and mesh health with your team.

Buoyant Cloud screenshot

You can get support directly from the Linkerd maintainers

While Istio support requires going to a third-party vendor, you can get Linkerd support from the creators and maintainers themselves. Linkerd help is available around the clock in a variety of levels, from erd’s thriving and friendly open source community all the way to 24x7x365 Linkerd support from the creators of Linkerd.

Why choose Istio over Linkerd?

There are some perfectly valid reasons why you might choose Istio over Linkerd. For one, Linkerd is very Kuberenetes-focused, and organizations that are not ready to adopt the Kubernetes operational model as their primary model may find Istio better suited to their needs. Istio is also extremely configurable, and users that have very specialized requirements may only be able to satisfy those requirements with Istio.

Of course, choosing Istio only makes sense if you have the engineering resources to dedicate to it. Istio adopters often resort to handling its complexity by hiring a team of service mesh engineers.

The bottom line

If security is a primary concern; if you want a service mesh that “just works” and gets out of your way; if speed and resource consumption are critical; and if you are bought into the Kubernetes model of operations—Linkerd will be the best choice. If you have highly specialized requirements that Linkerd can’t meet, and are willing to make the requisite engineering investment in Istio, then you should use Istio.

But don’t take our word for it: give Linkerd a try and see for yourself. You can follow this Linkerd 101 video tutorial for a step-by-step guide and, if you have questions, just hit us up on the Linkerd Slack. We’re always happy to help!

>> Need help evaluating Linkerd? Book a meeting with us today! <<