(“This Week in Glean” is a series of blog posts that the Glean Team at Mozilla is using to try to communicate better about our work. They could be release notes, documentation, hopes, dreams, or whatever: so long as it is inspired by Glean.)
All "This Week in Glean" blog posts are listed in the [TWiG index](https://mozilla.github.io/glean/book/appendix/twig.html)
(and on the [Mozilla Data blog](https://blog.mozilla.org/data/category/glean/)).
This article is [cross-posted on the Mozilla Data blog][datablog].
Migration to rely on [UniFFI] for code generation has started!
Right now adding new features to Glean [requires changes across all SDKs](https://mozilla.github.io/glean/dev/core/new-metric-type.html).
With UniFFI we can define the API of metric types once, implement it in Rust and get the code for the SDKs generated automatically.
Less manual code means less potential for bugs and easier maintenance.
The [`uniffi` branch][uniffi-branch] is used for slowly migrating Glean piece by piece.
Most of the metric types are [defined in UDL now][glean.udl] and the Kotlin code base has been migrated to it already,
with all tests passing again.
Work on this will continue next year, migrating the Swift, Python and Rust SDKs and then eventually merging it back into the main branch,
so we can ship it to users.
From there adding new metrics will require less implementation work and thus will allow us to follow up with some of the existing but currently paused requests.
We [released][release-page] 9 major versions of Glean and did 33 releases in total.
We're very liberal with breaking changes & major releases,
though we make sure that upgrades require minimal changes where possible.
The Kotlin, Swift, Python & Rust SDKs are versioned all the same,
so a breaking change in only one SDK will still cause a major release for other SDKs, even without breaking changes.
More products and projects are now using Glean, including [Rally studies][rally], the [Mozilla VPN client][vpn], and the new version of [Focus for Android](https://dictionary.telemetry.mozilla.org/apps/focus_android).
A full list of products is available in the [Glean Dictionary][dictionary].
To ease integration between telemetry collected in Gecko and telemetry collected in the Android parts of the browser
we're now [shipping Glean through GeckoView][geckoview]. (After [crashing it][crash], fixing it and shipping it again without new bugs cropping up.)
There's some work to be done next year to make local development easier again and to automate some of the tasks of upgrading Glean across applications.
These are the tools I'm much less directly involved in,
but they make up an important part of the Glean ecosystem.
After all these are where users actually get to analyze at the data they collect.
[GLAM] currently only serves data for Firefox Desktop using legacy telemetry data as well as Firefox for Android using Glean data.
Things are in place to enable more Glean-powered products soon, once we [iron out some details around data expectations from applications][build-date].
The [Glean Dictionary][dictionary] saw near-weekly releases
and went from "promising prototype" into "valuable production tool" this year,
thanks to a lot of work from [wlach] and [linh].
It was the basis of several initiatives such as [metric annotations][annotations] and [tagging support][tags].
These things will be helpful to make data at Mozilla more discoverable and better documented.
The primary tool for analyzing data at Mozilla is now [Looker].
Folks have been very busy making more and more data accessible to both data experts and non-experts alike[^1].
Glean data is (more or less) automatically available in Looker explores, for example [event counts](https://docs.telemetry.mozilla.org/cookbooks/looker/event_counts_explore.html).
Instead of bringing up ad hoc dashboards for initiatives when needed we can usually recommend that people just build things in Looker.
That has the major advantage that exploration beyond what the dashboard summarizes is just one or two clicks away.
I'm excited to shift my own use away from [fiddling around with SQL][sql] to more approachable explores & dashboards,
