Jess's Blog

Engineer in Residence at the Rust Foundation

Jess Izen — Thu, 27 Aug 2026 00:00:00 +0000

This was pulled from my old LinkedIn.

I am excited to put on an additional hat: Engineer in Residence at the Rust Foundation, seconded for a year by AWS.

Rust is in a moment of great opportunity, and I believe that the Rust community can chart a new course for the industry in supply chain security and maintainer sustainability. I'm looking forward to getting my hands dirty working full-time on infrastructure and programs that reach all Rust users.

Besides the colleagues I mentioned in the linked post from the Rust Foundation, Rust Project, Rust community, and AWS, I want to give a special thank you to open source leaders that have shared a steady stream of advice about how companies like AWS can fit into this story while supporting maintainer autonomy: Josh Aas, Benjamin Nickolls, Henri Yandell, Alexander Scammon, George Chellapa Ph.D., Duane O'Brien, Æva Black.

Funding Rust through the Rust Commercial Network

Jess Izen — Tue, 30 Jun 2026 00:00:00 +0000

This was pulled from my old LinkedIn.

Does your company depend on Rust?

Join industry peers in funding OSS maintainers and development time for the Rust ecosystem and toolchain. We are pooling funds for both basic maintenance and directed work towards areas affecting our businesses.

You can see open funding opportunities in the RCN funding directory.

Predrag Gruevski and I are launching this new funding initiative through the Rust Commercial Network (RCN), part of the Rust Foundation. Membership is not required to participate.

Small and large contributions are welcome. If you want to help seed the project, we’re preparing a launch announcement with the initial projects funded, participating companies, and total amount raised. Founding partners include Amazon Web Services (AWS), OpenAI for Developers, and Arm.

Predrag and I are holding office hours starting next week, July 8 at 8am US/Pacific. We can help you route an OSS budget, pitch a budget to your leadership, or figure out logistics for Rust OSS work you have in mind.

Come to office hours or discuss async.

Update: These office hours are no longer running.

Wide events and metrique 0.1.24

Jess Izen — Tue, 14 Apr 2026 00:00:00 +0000

This was pulled from my old LinkedIn.

There's been a lot of interest in flight recording lately, such as Russell Cohen and my dial9 tokio flight recorder.

But, metrics are still very useful! After all, you need a metric to go red or a dashboard to look weird, in order to know to analyze traces in the first place. In particular, I prefer wide events, which lets you emit simple metrics, but also preserve high-cardinality metadata for drill downs or aggregating for trends. The workflow I use is, metric to alert/dashboard, wide event queries to contextualize, trace to deep dive.

In support of this, I maintain a wide-events-as-metrics library, metrique, which is the main Rust metrics library used inside Amazon. The TLDR is that it lets you use macros to tag structs with metrics, which do the "right thing" on drop, very cheaply, with embedded measurements and metadata. Its API is very async-friendly: you can fan out to child tasks that fold data back into your main emission, and delay flushing (but not foreground flow) until all segments finish. Currently EMF, JSON, and custom formats are supported, OTLP coming soon.

Our latest release, 0.1.24, brings a few nice features:

We now have a turnkey integration with tokio-metrics (which I also maintain), that allows automatically emitting tokio runtime metrics as metrique records. We already had a similar integration for metrics.rs aggregated metrics. But, with metrique, we are setting ourselves up to fold "what was the state of the tokio runtime during this request" into wide event records, which is neat. Kudos to Julian Montes de Oca for this feature.

Second, we now support emitting "properties" (metadata strings) as ["arrays", "of", ["possibly", "nested"], "strings"]. AWS Cloudwatch Log Insights and most other backends gracefully handles complex properties in EMF (or JSON) records, but AFAIK, few off the shelf EMF libraries do. I've frequently found myself manually casting properties to "list,of,values", so this should be a nice paper cut fix.

Finally, I added support for Counter::increment_owned, which adds tokio friendly bounds to its guard. It lets you bump up a global counter that captures eg current requests in flight for one wide event, and decrement the counter after the request ends.

We will be tabling at TokioConf next week, come find us!

Lambda Rust Runtime 1.1.1

Jess Izen — Fri, 13 Mar 2026 00:00:00 +0000

This was pulled from my old LinkedIn.

The Lambda Rust Runtime just published our first big release post-1.x.

The headline new feature is concurrent invocation processing on a single lambda instance, using tokio¹. We have an open issue about adding further runtime options here.

This was a tricky release to plan for. We knew we wanted to improve ergonomics, since we had to lock down a lot of previously wide-open types for 1.0. Over the years, we had gotten comfortable releasing a rapid-fire stream of breaking lambda-events versions to keep up with AWS record changes. (Sure was nice while it lasted)

The new builders for event types were a good compromise, since we had to tag our previously public event types as #[non_exhaustive] for 1.0. Luciano Mammino added some custom builders for SQS & Kinesis to keep stream processing nice. And then, Astraea S. added a generalized builder for all other events (bon under the hood).

I also like what we did with the extension API's telemetry records. They are now optionally generic, which lets you deserialize directly into json (or a fancier type) with no intermediate parsing. This brings the ergonomics closer to managing a regular invocation event handler. (That was a slog of a PR, thanks Raphaël Thériault)

Kudos and appreciation to Davide Melfi for leading the release!

Release notes

Come to TokioConf in Portland, 4/20-4/23.

AWS Lambda officially supports Rust

Jess Izen — Fri, 14 Nov 2025 00:00:00 +0000

This was pulled from my old LinkedIn.

Starting today, AWS Lambda functions officially support Rust!

Release blog

You can install the supporting runtime via crates.io.

I am a maintainer of the Rust lambda runtime. It's exciting to see what started as a scrappy, community-driven project reach official status. This comes with SLAs and roadmap support that will give developers confidence to build in Rust on Lambda.

Excited to see what new ideas Astraea Quinn S. and the Lambda team bring to the open source project!

And, credit to David Calavera for founding the project, and thank you to champions like Luciano Mammino and James Eastham for helping the runtime achieve industry adoption.

Runtime 1.0 release notes