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Add configurable Axum buffered JSON body limits #407

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e867c12
feat(axum): configure buffered JSON body limits
ChristianPavilonis Oct 6, 2026
cb617a3
Merge corrected lower-stack fixture lock
ChristianPavilonis Nov 10, 2026
90b5e6a
Merge corrected lower-stack feature and CI contracts
ChristianPavilonis Nov 10, 2026
4856d95
fix(ci): sync buffered-body fixture MIME dependency locks
ChristianPavilonis Nov 10, 2026
b082ae6
Merge managed demo logging regression alignment
ChristianPavilonis Nov 10, 2026
8a2a0b7
Merge native-only scaffold correction into body-limit stack
ChristianPavilonis Nov 10, 2026
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12 changes: 12 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,18 @@

## Unreleased

### Axum buffered JSON limits and body API

Axum now defaults framework-managed JSON buffering to 2 MiB, exactly 2,097,152 bytes.

@aram356 aram356 Nov 11, 2026

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🔧 Breaking changes aren't flagged, and "representation unchanged" is inaccurate

For existing Axum apps, this entry changes behavior that the CHANGELOG normally marks with - **Breaking:** (see "Policy-Aware Axum Servers"):

  • The Axum Json<T> / ValidatedJson<T> default drops from 8 MiB to 2 MiB.

  • Explicit caps above the ceiling are now silently lowered to it and return 413:

    • always: json_within(N) and ValidatedJsonWithin<T, N>;
    • on application/json / +json requests: body_bytes(N), form_within(N), the Form family, and pre-dispatch body_bytes / transform_body(max_input, ..).

    "Explicit application caps may tighten the ceiling" hides that clamp.

  • New public method: Body::with_buffered_json_policy.

  • Body's Debug output gains an ingress_buffer field, and Body grows from 40 to 64 bytes, so "representation remain unchanged" doesn't hold.

Please also update the rustdoc that now describes the wrong behavior:

  • DEFAULT_INBOUND_JSON_BYTES ("accepted by JSON extractors (8 MiB)", context.rs:32)
  • body_bytes ("under the caller's byte cap", context.rs:343)
  • json_within ("Buffers at most max bytes", context.rs:654)

All three should mention the native ceiling.

Set `EDGEZERO__ADAPTER__JSON_BODY_LIMIT_BYTES` for standalone hosting, or use the fallible
`with_json_body_limit_bytes` builder on `AxumRunOptions` or `AxumDevServer`. Explicit
application caps may tighten the ceiling. Overflow is typed HTTP 413; malformed JSON remains
400. Taken streams, forwarding, manual collection, and other providers' defaults are unchanged.

The current `Body`/`BodyPayload` representation and exact egress ownership remain unchanged.
Ingress buffering policy and cache provenance survive context reconstruction independently of
mutable headers and extensions, and are removed at raw payload transport boundaries.

### Portable HTTP And Request Lifecycles (PR #275)

The changes below cover [PR #275](https://github.com/IABTechLab/edgezero/pull/275), including its
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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions Cargo.toml
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Expand Up @@ -75,6 +75,7 @@ libc = "0.2"
miniz_oxide = { version = "=0.8.9", default-features = false, features = ["simd", "with-alloc"] }
log-fastly = "=0.13.1"
matchit = "0.9"
mime = "0.3"
once_cell = "1"
# 4.2 asserts that no read reference outlives its transaction. That check
# is what caught the `AccessGuard` bug in the axum KV store, so the
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2 changes: 2 additions & 0 deletions crates/edgezero-adapter-axum/Cargo.toml
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Expand Up @@ -21,6 +21,7 @@ axum = [
"dep:http-body",
"dep:hyper",
"dep:hyper-util",
"dep:mime",
"dep:reqwest",
"dep:redb",
]
Expand Down Expand Up @@ -51,6 +52,7 @@ http-body = { workspace = true, optional = true }
hyper = { workspace = true, optional = true }
hyper-util = { workspace = true, optional = true }
log = { workspace = true }
mime = { workspace = true, optional = true }
redb = { workspace = true, optional = true }
reqwest = { workspace = true, optional = true }
serde = { workspace = true }
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4 changes: 2 additions & 2 deletions crates/edgezero-adapter-axum/src/connection.rs
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Expand Up @@ -1498,7 +1498,7 @@ mod tests {

#[tokio::test(flavor = "current_thread")]
async fn json_extractor_overflow_reaches_custom_renderer_without_retry_after() {
use edgezero_core::context::DEFAULT_INBOUND_JSON_BYTES;
use crate::run_options::JsonBodyLimit;
use edgezero_core::extractor::Json;

#[edgezero_core::action]
Expand All @@ -1517,7 +1517,7 @@ mod tests {
.body(Body::from("extractor overflow"))
.expect("custom error response")
});
let cap = DEFAULT_INBOUND_JSON_BYTES;
let cap = JsonBodyLimit::DEFAULT.get().get();
let body = serde_json::to_string(&serde_json::json!("x".repeat(cap - 1)))
.expect("valid oversized JSON string");
assert_eq!(body.len(), cap + 1);
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