Linkerd Edge Release Roundup: 21 June 2023

Linkerd’s edge releases are a big part of our development process that we’re going to start talking more about – and so far in June, we’ve done a couple of edge releases that we think everyone should definitely know about!

On June 20th, we released edge-23.6.2, which introduces timeout capabilities for HTTPRoutes following the standard proposed in Gateway API GEP-1742. It also includes a host of small bugfixes and two fixes from community members:

• linkerd check won’t skip validation checks when Linkerd is installed with HA mode using Helm. Thanks Takumi Sue!

• Allow specifying the Docker builder to use when building multi-arch Docker artifacts. Thanks Mark Robinson!

And on June 13th, we released edge-23.6.1. This edge release switched the Linkerd CNI plugin so that it always runs in chained mode to reduce startup races, as well as bringing in two more community fixes:

• Topology-aware service routing can now be correctly turned off while still under load. Thanks again, Mark Robinson!

• Last but not least, support specifying a logFormat in the multi-cluster Link Helm Chart. Thanks, Arnaud Beun!

As always, you can install the latest edge release by running:

curl --proto '=https' --tlsv1.2 -sSfL https://run.linkerd.io/install-edge | sh

GEP-1742 timeout support (edge-23.6.2)

Gateway API Enhancement Proposals - GEPs - are part of the formal process for modifying the Gateway API, and GEP-1742 introduces the ability to specify two kinds of timeouts in an HTTPRoute. Timeouts are an important feature for reliability, so Linkerd has been following - and participating in - this GEP with great interest.

Since it’s still in the “Provisional” state at present, it’s possible that we may need to make changes here before the next stable Linkerd release, but it’s far enough along (see Gateway API PR#1997) that we think it’s worth implementing to let people try out. Let us know how it works for you!

CNI changes (edge-23.6.1)

A big part of what Linkerd has to handle at startup is setting up the network to allow Linkerd to route within the mesh, which sometimes means using the Linkerd CNI plugin. CNI plugins are tricky, especially when it comes to ordering (as you learned if you watched the Service Mesh Academy episode about startup!), and we’ve run across a few situations where race conditions with the CNI plugin could result in problems.

To combat these race conditions, we’ve switched our CNI plugin to only use chained mode. Instead of letting the Linkerd CNI plugin create a CNI configuration if it doesn’t find one, the plugin will now always wait for some other part of the CNI chain to create the configuration first. This makes it much less likely that some other CNI plugin will accidentally overwrite Linkerd’s configuration, regardless of the CNI plugin provider that’s used.

How to give feedback

We would be delighted to hear how these releases work out for you! The full changelogs are at https://github.com/linkerd/linkerd2/releases/tag/edge-23.6.1 and https://github.com/linkerd/linkerd2/releases/tag/edge-23.6.2, and we’d love to hear your feedback on Slack or at the new Buoyant Linkerd Forum. Looking forward to hearing from you – happy meshing!!

Linkerd generally does new edge releases weekly; watch this space to keep up-to-date. Feedback on this blog series is welcome! Just ping @flynn on the Linkerd Slack.