Just bumping this because it ended up in my spam folder.

On Tue, Sep 1, 2026 at 6:26 PM rahul mahadev <[email protected]>
wrote:

> Hi all,
>
> I'd like to propose a recommended User-Agent format for REST catalog
> clients, so a client identifies itself to a catalog in a consistent,
> parseable way.
>
>
> *Today it's inconsistent:*- iceberg-java sends no User-Agent by default
> (it's opt-in via config).
> - pyiceberg sends "PyIceberg/<version>", iceberg-rust
> "iceberg-rs/<version>",
>   iceberg-go "GoIceberg/<version>" basically all different naming.
> - X-Client-Version carries the library version in Java/Python but the REST
>   spec version in Rust/Go.
> - None of this is described in the spec.
>
> That makes it hard for a catalog operator to tell what's actually calling,
> which matters for observability, debugging, and support.
>
> *Proposal*: use the standard User-Agent header (RFC 7231) i.e. whitespace-
> separated product/version tokens, most specific first (engine ->
> integration -> Iceberg library -> runtime), with an optional parenthesized
> comment for extra context. Example:
>
>   Spark/4.0.0 iceberg-spark/1.9.0 iceberg-java/1.9.0 (scala/2.13.16)
>
> The Iceberg library token is the one piece every client can supply, so it
> should always be present. The header is optional and informational only:
> servers must not reject on it, must not use it for auth or trust decisions,
> and it is not a capability negotiation mechanism.
>
>
> *Draft PR with the spec
> change:https://github.com/apache/iceberg/pull/17727
> <https://github.com/apache/iceberg/pull/17727>*
>
> If the format looks right, the follow-ups would be conforming the client
> libraries (java / python / rust / go) to emit it.
>
> A few open questions:
> 1. Should we also reconcile X-Client-Version (library vs spec version
>    across clients), or leave it and treat User-Agent as the canonical
>    identity going forward?
> 2. Naming: keep the existing library names (PyIceberg, iceberg-rs,
>    GoIceberg) or converge on one scheme (iceberg-<lang>)?
> 3. Is a separate environment token (e.g. prod/staging) useful, or does
>    that belong in the comment?
> 4. Any other fields we want to capture ?
>
> Feedback welcome.
>
> Thanks,
> Rahul Mahadev (github: rahulsmahadev)
>

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