Linkerd Edge Release Roundup: October 2024

Welcome to the October 2024 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!

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.

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, and this batch of releases is definitely no exception. Huge thanks to Lauri Kuittinen, Vadim Makerov, and @kristjankullerkann-wearemp for their contributions! You’ll find more information about all of these contributions in the release-by-release details below.

Recommendations and breaking changes

All these releases are recommended for general use. There is one breaking change: starting in edge-24.9.2, the timestamp in JSON-formatted proxy logs are now ISO8601 strings (for example, 2024-09-09T13:38:56.919918Z). This is an oft-requested feature but, of course, still a breaking change.

Additionally, it’s important to realize that edge-24.9.3 introduces a change to the Link CRD that’s not compatible with previous versions of the Linkerd CLI. If you’re using Linkerd multicluster, you’ll need to either upgrade every linkerd cluster to edge-24.9.3 at the same time, or plan to hold off until edge-24.10.2.

The releases

September’s releases bring in some new improvements to Linkerd statistics and also some important bugfixes. Of course, each edge release includes many dependency updates which we won’t list here, but you can find them in the release notes for each release.

edge-24.9.3 (September 27, 2024)

edge-24.9.3 fixes a panic that would occur if a retried response arrived before the retried request was complete. This may sound bizarre, but it is allowed by the HTTP/2 specification, and using wire-gprc with retries enabled tended to trip over this in the real world.

This release also supports configuring the timeout and failure threshold for health probes for the multicluster gateway, to improve reliability in the face of networking issues between clusters. A caution with edge-24.9.3 is that its CLI will have trouble with linkerd clusters that are running earlier releases (looking into the future a bit, edge-24.10.2 fixes this issue).

edge-24.9.2 (September 12, 2024)

Starting in edge-24.9.2, JSON-formatted proxy logs render timestamps as ISO8601 strings, rather than fractional seconds since proxy startup (fixing issue 12505). For example, you might see a log like

{
  "timestamp": "2024-09-09T13:38:56.919918Z",
  "level": "INFO",
  "fields": { "message": "Using single-threaded proxy runtime" },
  "target": "linkerd2_proxy::rt",
  "threadId": "ThreadId(1)"
}

This release also publishes quite a few new internal metrics to provide insight into how the proxy runtime is performing, and publishes the proxy’s current time as a metric, which should make it easier to be sure of when certificates will need to be rotated. It also allows setting TCP_USER_TIMEOUT for TCP sockets (thanks, Vadim Makerov!), updates the Helm documentation to include recently-added values, and removes some redundant dashes in the identity controller’s Helm templates. Finally, Linkerd Viz in this release supports reading credentials from a Secret for using Prometheus with HTTP Basic authentication.

edge-24.9.1 (September 6, 2024)

In edge-24.9.1, Linkerd Viz gets the new linkerd viz stat-inbound and linkerd viz stat-outbound commands, which provide cleaner access from the command line to the new metrics available based on Gateway API routes, for example:

$ linkerd viz stat-outbound -n faces deploy/face
NAME  SERVICE    ROUTE         TYPE       BACKEND     SUCCESS   RPS  LATENCY_P50  LATENCY_P95  LATENCY_P99  TIMEOUTS  RETRIES
face  smiley:80  smiley-route  HTTPRoute               78.36%  6.32         41ms       5886ms       9177ms     0.00%    0.00%
                 ├─────────────────────►  smiley:80    79.34%  5.57         20ms       5725ms       9145ms     0.00%
                 └─────────────────────►  smiley2:80   71.11%  0.75         22ms       6850ms       9370ms     0.00%
face  color:80   color-route   GRPCRoute               80.10%  6.37         25ms         48ms         50ms     0.00%    0.00%
                 ├─────────────────────►  color:80     80.12%  2.68         12ms         24ms         25ms     0.00%
                 └─────────────────────►  color2:80    80.00%  3.67         12ms         24ms         25ms     0.00%

In this example, we have traffic splitting set up using GRPCRoutes and HTTPRoutes.

This release also adds dualstack support for ExternalWorkload, Helm support for tuning liveness and readiness probe timeouts (thanks @kristjankullerkann-wearemp!), and Helm support for configuring externalTrafficPolicy for multicluster gateways (thanks Lauri Kuittinen!).

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.