feat(quota): Rate limit attachments by item count (#4377)

Attachment quotas and rate limits are currently defined in bytes, so we
have no way to prevent an abusively high number of very small (or even
empty) attachments.

CHANGELOG.md

@@ -11,6 +11,7 @@
 **Features**:
 
 - Add data categories for Uptime and Attachment Items. ([#4363](https://github.com/getsentry/relay/pull/4363), [#4374](https://github.com/getsentry/relay/pull/4374))
+- Add ability to rate limit attachments by count (not just by the number of bytes). ([#4377](https://github.com/getsentry/relay/pull/4377))
 
 ## 24.11.2
 

relay-quotas/src/quota.rs

@@ -170,10 +170,12 @@ impl ItemScoping<'_> {
 
 /// The unit in which a data category is measured.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-enum CategoryUnit {
+pub enum CategoryUnit {
+    /// Counts the number of items.
     Count,
+    /// Counts the number of bytes across items.
     Bytes,
-    Batched,
+    /// Counts the accumulated times across items.
     Milliseconds,
 }
 
@@ -199,9 +201,9 @@ impl CategoryUnit {
             | DataCategory::ProfileChunk
             | DataCategory::Uptime
             | DataCategory::MetricSecond
-            | DataCategory::AttachmentItem => Some(Self::Count),
+            | DataCategory::AttachmentItem
+            | DataCategory::Session => Some(Self::Count),
             DataCategory::Attachment => Some(Self::Bytes),
-            DataCategory::Session => Some(Self::Batched),
             DataCategory::ProfileDuration => Some(Self::Milliseconds),
 
             DataCategory::Unknown => None,

relay-server/src/envelope.rs

@@ -49,7 +49,7 @@ use relay_quotas::DataCategory;
 use relay_sampling::DynamicSamplingContext;
 use serde::de::DeserializeOwned;
 use serde::{Deserialize, Serialize};
-use smallvec::SmallVec;
+use smallvec::{smallvec, SmallVec};
 
 use crate::constants::DEFAULT_EVENT_RETENTION;
 use crate::extractors::{PartialMeta, RequestMeta};
@@ -632,6 +632,14 @@ pub struct Item {
     payload: Bytes,
 }
 
+/// Expresses the purpose of counting quantities.
+///
+/// Sessions are counted for rate limiting enforcement but not for outcome reporting.
+pub enum CountFor {
+    RateLimits,
+    Outcomes,
+}
+
 impl Item {
     /// Creates a new item with the given type.
     pub fn new(ty: ItemType) -> Self {
@@ -670,13 +678,38 @@ impl Item {
     /// Returns the number used for counting towards rate limits and producing outcomes.
     ///
     /// For attachments, we count the number of bytes. Other items are counted as 1.
-    pub fn quantity(&self) -> usize {
+    pub fn quantities(&self, purpose: CountFor) -> SmallVec<[(DataCategory, usize); 1]> {
         match self.ty() {
-            ItemType::Attachment => self.len().max(1),
-            // NOTE: This is semantically wrong. An otel trace contains may contain many spans,
-            // but we cannot easily count these before converting the trace into a series of spans.
-            ItemType::OtelTracesData => 1,
-            _ => 1,
+            ItemType::Event => smallvec![(DataCategory::Error, 1)],
+            ItemType::Transaction => smallvec![(DataCategory::Transaction, 1)],
+            ItemType::Security | ItemType::RawSecurity => {
+                smallvec![(DataCategory::Security, 1)]
+            }
+            ItemType::Nel => smallvec![],
+            ItemType::UnrealReport => smallvec![(DataCategory::Error, 1)],
+            ItemType::Attachment => smallvec![
+                (DataCategory::Attachment, self.len().max(1)),
+                (DataCategory::AttachmentItem, 1)
+            ],
+            ItemType::Session | ItemType::Sessions => match purpose {
+                CountFor::RateLimits => smallvec![(DataCategory::Session, 1)],
+                CountFor::Outcomes => smallvec![],
+            },
+            ItemType::Statsd | ItemType::MetricBuckets => smallvec![],
+            ItemType::FormData => smallvec![],
+            ItemType::UserReport => smallvec![],
+            ItemType::UserReportV2 => smallvec![(DataCategory::UserReportV2, 1)],
+            ItemType::Profile => smallvec![(DataCategory::Profile, 1)],
+            ItemType::ReplayEvent | ItemType::ReplayRecording | ItemType::ReplayVideo => {
+                smallvec![(DataCategory::Replay, 1)]
+            }
+            ItemType::ClientReport => smallvec![],
+            ItemType::CheckIn => smallvec![(DataCategory::Monitor, 1)],
+            ItemType::Span | ItemType::OtelSpan => smallvec![(DataCategory::Span, 1)],
+            // NOTE: semantically wrong, but too expensive to parse.
+            ItemType::OtelTracesData => smallvec![(DataCategory::Span, 1)],
+            ItemType::ProfileChunk => smallvec![(DataCategory::ProfileChunk, 1)], // TODO: should be seconds?
+            ItemType::Unknown(_) => smallvec![],
         }
     }
 
@@ -688,35 +721,6 @@ impl Item {
         )
     }
 
-    /// Returns the data category used for generating outcomes.
-    ///
-    /// Returns `None` if outcomes are not generated for this type (e.g. sessions).
-    pub fn outcome_category(&self) -> Option<DataCategory> {
-        match self.ty() {
-            ItemType::Event => Some(DataCategory::Error),
-            ItemType::Transaction => Some(DataCategory::Transaction),
-            ItemType::Security | ItemType::RawSecurity => Some(DataCategory::Security),
-            ItemType::Nel => None,
-            ItemType::UnrealReport => Some(DataCategory::Error),
-            ItemType::Attachment => Some(DataCategory::Attachment),
-            ItemType::Session | ItemType::Sessions => None,
-            ItemType::Statsd | ItemType::MetricBuckets => None,
-            ItemType::FormData => None,
-            ItemType::UserReport => None,
-            ItemType::UserReportV2 => Some(DataCategory::UserReportV2),
-            ItemType::Profile => Some(DataCategory::Profile),
-            ItemType::ReplayEvent | ItemType::ReplayRecording | ItemType::ReplayVideo => {
-                Some(DataCategory::Replay)
-            }
-            ItemType::ClientReport => None,
-            ItemType::CheckIn => Some(DataCategory::Monitor),
-            ItemType::Span | ItemType::OtelSpan => Some(DataCategory::Span),
-            ItemType::OtelTracesData => None,
-            ItemType::ProfileChunk => Some(DataCategory::ProfileChunk),
-            ItemType::Unknown(_) => None,
-        }
-    }
-
     /// Returns `true` if this item's payload is empty.
     pub fn is_empty(&self) -> bool {
         self.payload.is_empty()

relay-server/src/services/processor/dynamic_sampling.rs

@@ -11,7 +11,7 @@ use relay_sampling::config::RuleType;
 use relay_sampling::evaluation::{ReservoirEvaluator, SamplingEvaluator};
 use relay_sampling::{DynamicSamplingContext, SamplingConfig};
 
-use crate::envelope::ItemType;
+use crate::envelope::{CountFor, ItemType};
 use crate::services::outcome::Outcome;
 use crate::services::processor::{
     EventProcessing, ProcessEnvelopeState, Sampling, TransactionGroup,
@@ -116,18 +116,16 @@ pub fn drop_unsampled_items(state: &mut ProcessEnvelopeState<TransactionGroup>,
         .take_items_by(|item| *item.ty() != ItemType::Profile);
 
     for item in dropped_items {
-        let Some(category) = item.outcome_category() else {
-            continue;
-        };
-
-        // Dynamic sampling only drops indexed items. Upgrade the category to the index
-        // category if one exists for this category, for example profiles will be upgraded to profiles indexed,
-        // but attachments are still emitted as attachments.
-        let category = category.index_category().unwrap_or(category);
-
-        state
-            .managed_envelope
-            .track_outcome(outcome.clone(), category, item.quantity());
+        for (category, quantity) in item.quantities(CountFor::Outcomes) {
+            // Dynamic sampling only drops indexed items. Upgrade the category to the index
+            // category if one exists for this category, for example profiles will be upgraded to profiles indexed,
+            // but attachments are still emitted as attachments.
+            let category = category.index_category().unwrap_or(category);
+
+            state
+                .managed_envelope
+                .track_outcome(outcome.clone(), category, quantity);
+        }
     }
 
     // Mark all remaining items in the envelope as un-sampled.

relay-server/src/utils/managed_envelope.rs

@@ -10,7 +10,7 @@ use chrono::{DateTime, Utc};
 use relay_quotas::{DataCategory, Scoping};
 use relay_system::Addr;
 
-use crate::envelope::{Envelope, Item};
+use crate::envelope::{CountFor, Envelope, Item};
 use crate::extractors::RequestMeta;
 use crate::services::outcome::{DiscardReason, Outcome, TrackOutcome};
 use crate::services::processor::{Processed, ProcessingGroup};
@@ -52,7 +52,6 @@ pub enum ItemAction {
     /// Keep the item.
     Keep,
     /// Drop the item and log an outcome for it.
-    /// The outcome will only be logged if the item has a corresponding [`Item::outcome_category()`].
     Drop(Outcome),
     /// Drop the item without logging an outcome.
     DropSilently,
@@ -263,12 +262,13 @@ impl ManagedEnvelope {
             ItemAction::Keep => true,
             ItemAction::DropSilently => false,
             ItemAction::Drop(outcome) => {
-                if let Some(category) = item.outcome_category() {
+                for (category, quantity) in item.quantities(CountFor::Outcomes) {
                     if let Some(indexed) = category.index_category() {
-                        outcomes.push((outcome.clone(), indexed, item.quantity()));
+                        outcomes.push((outcome.clone(), indexed, quantity));
                     };
-                    outcomes.push((outcome, category, item.quantity()));
-                };
+                    outcomes.push((outcome.clone(), category, quantity));
+                }
+
                 false
             }
         });
@@ -360,7 +360,7 @@ impl ManagedEnvelope {
                     tags.has_transactions = summary.secondary_transaction_quantity > 0,
                     tags.has_span_metrics = summary.secondary_span_quantity > 0,
                     tags.has_replays = summary.replay_quantity > 0,
-                    tags.has_checkins = summary.checkin_quantity > 0,
+                    tags.has_checkins = summary.monitor_quantity > 0,
                     tags.event_category = ?summary.event_category,
                     cached_summary = ?summary,
                     recomputed_summary = ?EnvelopeSummary::compute(self.envelope()),