Linkerd Edge Release Roundup: June 2025

Welcome to the June 2025 Edge Release Roundup post, where we dive into the most recent edge releases to help keep everyone up to date on the latest and greatest! This post covers edge releases from April and May, notably including edge-25.4.4, which corresponds to Linkerd 2.18. However, since the lion’s share of 2.18’s new functionality was covered in the April 2025 Roundup post, we’ll be mostly seeing smaller changes in this Roundup.

How to give feedback

Edge releases are a snapshot of our current development work on main; by definition, they always have the most recent features but they may have incomplete features, features that end up getting rolled back later, or (like all software) even bugs. That said, edge releases are intended for production use, and go through a rigorous set of automated and manual tests before being released. Once released, we also document whether the release is recommended for broad use – and when needed, we go back and update the recommendations.

We would be delighted to hear how these releases work out for you! You can open a GitHub issue or discussion, join us on Slack, or visit the Buoyant Linkerd Forum – all are great ways to reach us.

Community contributions

We couldn’t do what we do without the Linkerd community, although this particular batch of releases makes that a little less obvious than usual. Huge thanks to Justin Seiser for his contributions to Linkerd’s OpenTelemetry support!

Recommendations and breaking changes

Our April 2025 Roundup post covered everything through edge-25.4.1, so we’ll be picking up from there. As noted earlier, edge releases are meant for real use, as this batch of releases shows: almost all of them can be recommended for everyone to use, with the exceptions being two edge releases that changed internal build processes and updated dependencies, but didn’t make any user-facing changes.

There are definitely some changes to be aware of in recent edge releases, too. We’ll start by reiterating a major point from the April 2025 Roundup post: in Linkerd 2.18, including all of the edge releases covered by this post, the Gateway API CRDs are mandatory, and our recommendation is that you install them yourself rather than having Linkerd install them for you. You can read more about this in the Linkerd Gateway API documentation, and of course the April 2025 Roundup post has more details on breaking changes leading up to Linkerd 2.18.

Additionally, as of edge-25.4.3 (and therefore included in Linkerd 2.18!), the default port for tracing is the OpenTelemetry port (4317) rather than the OpenCensus port (55678).

The releases

The first few edge releases in this Roundup, broadly speaking, are all about getting to Linkerd 2.18, which corresponds to edge-25.4.4. After that, we have a few releases cleaning up some small issues. Of course, each edge release includes many dependency updates, which we won’t list here, but which you can find in the release notes for each release.

edge-25.5.5 (May 29, 2025)

This release adds support for the k8s.pod.ip OpenTelemetry trace attribute. Thanks, Justin Seiser!

edge-25.5.4 (May 22, 2025)

This release correctly supports setting pod antiaffinity for the linkerd-multicluster chart.

edge-25.5.3 (May 15, 2025)

This release contains internal improvements, but no new capabilities over edge-25.5.1 – as such, we recommend that you skip it and go straight to edge-25.5.5!

edge-25.5.2 (May 08, 2025)

This release contains internal improvements, but no new capabilities over edge-25.5.1 – as such, we recommend that you skip it and go straight to edge-25.5.5!

edge-25.5.1 (May 02, 2025)

This edge release adds support for httproute.gateway.networking.k8s.io in an AuthorizationPolicy targetRef.

edge-25.4.4 (April 21, 2025)

With this release, Linkerd 2.18 is complete, and the version-2.18 tag points to edge-25.4.4!

Services with ports using appProtocol: linkerd.io/opaque will now only allow TCPRoutes to be attached to that port, and any unknown appProtocol value will be treated as linkerd.io/opaque. Additionally, both GRPCRoutes and HTTPRoutes may be attached to kubernetes.io/h2c ports, with GRPCRoutes taking precedence if both are present. Finally, the LINKERD2_PROXY_OUTBOUND_METRICS_HOSTNAME_LABELS is correctly honored for TLS hostname labels.

edge-25.4.3 (April 16, 2025)

This release changes the default port for tracing to the OpenTelemetry port (4317) rather than the OpenCensus port (55678). Additionally, it tweaks the CLI to make sure that the v1 Gateway API resources we rely on are present and gives a more specific command to install Gateway API CRDs if they’re not found.

edge-25.4.2 (April 09, 2025)

This release makes it easier to see the message telling you that you need to install the Gateway API CRDs when they are missing, by not showing all the usage information for linkerd install in that case. It also fixes a bug where metrics for the final request in a gRPC stream could show an UNKNOWN error rather than a success.

Installing the latest edge release

Installing the latest edge release needs just a single command.

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

You can also install edge releases with Helm.

Linkerd is for everyone

Linkerd is a graduated project of the Cloud Native Computing Foundation. Linkerd is committed to open governance. If you have feature requests, questions, or comments, we’d love to have you join our rapidly growing community! Linkerd is hosted on GitHub, and we have a thriving community on Slack, Twitter, and in mailing lists. Come and join the fun!

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.