travis-bowen opened a new pull request, #4404:
URL: https://github.com/apache/polaris/pull/4404
## Motivation
`RateLimiterFilter` previously returned HTTP 429 with an empty body and no
`Content-Type` header:
```java
ctx.abortWith(Response.status(Response.Status.TOO_MANY_REQUESTS).build());
```
Iceberg REST clients (pyiceberg, Spark, and any third-party caller) cannot
meaningfully parse this. The Iceberg Java client's
`DefaultErrorHandler.parseResponse()` attempts
`ErrorResponseParser.fromJson("")` on the empty body, catches the JSON parse
failure, and falls back to building an `ErrorResponse` with `message = ""`.
Since there is no `case 429:` in any `ErrorHandlers` switch, the result is
always:
```
RESTException("Unable to process: ")
```
— an opaque error with no actionable context for the caller.
## Changes
Add an Iceberg-compatible `ErrorResponse` JSON body to the 429 response,
following the exact pattern already used by `IcebergExceptionMapper` for all
other error codes:
```java
ctx.abortWith(
Response.status(Response.Status.TOO_MANY_REQUESTS)
.type(MediaType.APPLICATION_JSON_TYPE)
.entity(
ErrorResponse.builder()
.responseCode(Response.Status.TOO_MANY_REQUESTS.getStatusCode())
.withType("RateLimitExceededException")
.withMessage("Rate exceeded")
.build())
.build());
```
## Ecosystem Context
The Iceberg REST OpenAPI spec does not define a 429 response schema —
implementations are on their own. Surveying the major catalog implementations:
| Implementation | Body on 429? | Follows Iceberg `ErrorModel`? |
|---|---|---|
| AWS Glue | Yes | No (AWS `{"__type": "ThrottlingException", ...}` format) |
| Apache Nessie | Yes | No (Nessie `{"status": 429, "errorCode":
"TOO_MANY_REQUESTS", ...}` format) |
| Databricks Unity Catalog | Yes | No (Databricks `{"error_code":
"RESOURCE_EXHAUSTED", ...}` format) |
| Apache Polaris (this fix) | Yes | **Yes** |
All other catalogs return *some* JSON, but none follow the Iceberg
`ErrorModel` schema. With this fix, Polaris becomes the most spec-consistent
implementation — clients using `ErrorResponseParser` will be able to round-trip
the 429 body correctly.
## Compatibility
- Existing clients that ignore the 429 body are unaffected.
- Clients that previously hit the empty-body parse failure will now receive
a well-formed `ErrorResponse`.
- No change to status code or any other behavior.
## Tests
Added `testRateLimitedResponseHasIcebergErrorBody` — a full integration test
that performs a live HTTP request against a rate-limited endpoint, reads the
response body, and round-trips it through `ErrorResponseParser.fromJson(...)`
to prove Iceberg client compatibility. Asserts `Content-Type:
application/json`, `code == 429`, `type == "RateLimitExceededException"`, and
`message` contains `"Rate exceeded"`.
Fixes #4402
---
> This fix was developed with AI assistance (Claude). The author has
reviewed the change end-to-end and takes full responsibility for correctness
and ASF licensing compliance.
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