feat(buffer): Disable flush-to-disk for ephemeral storage

CHANGELOG.md

@@ -6,6 +6,11 @@
 
 - To prevent false positives, non-public email addresses (e.g. `user@localhost`) are no longer scrubbed by default. ([#5737](https://github.com/getsentry/relay/pull/5737))
 
+**Features**:
+
+- Envelope buffer: Add option to disable flush-to-disk on shutdown. ([#5751](https://github.com/getsentry/relay/pull/5751))
+
+
 **Internal**:
 
 - Calculate and track accepted bytes per individual trace metric item via `TraceMetricByte` data category. ([#5744](https://github.com/getsentry/relay/pull/5744))

relay-config/src/config.rs

@@ -1024,6 +1024,14 @@ pub struct EnvelopeSpool {
     /// Defaults to 1.
     #[serde(default = "spool_envelopes_partitions")]
     pub partitions: NonZeroU8,
+    /// Whether the database defined in `path` is on an ephemeral storage disk.
+    ///
+    /// With `ephemeral: true`, Relay does not spool in-flight data to disk
+    /// during graceful shutdown. Instead, it attempts to process all data before it terminates.
+    ///
+    /// Defaults to `false`.
+    #[serde(default)]
+    pub ephemeral: bool,
 }
 
 impl Default for EnvelopeSpool {
@@ -1036,6 +1044,7 @@ impl Default for EnvelopeSpool {
             disk_usage_refresh_frequency_ms: spool_disk_usage_refresh_frequency_ms(),
             max_backpressure_memory_percent: spool_max_backpressure_memory_percent(),
             partitions: spool_envelopes_partitions(),
+            ephemeral: false,
         }
     }
 }
@@ -2347,6 +2356,11 @@ impl Config {
         self.values.spool.envelopes.partitions
     }
 
+    /// Returns `true` if the data is stored on ephemeral disks.
+    pub fn spool_ephemeral(&self) -> bool {
+        self.values.spool.envelopes.ephemeral
+    }
+
     /// Returns the maximum size of an event payload in bytes.
     pub fn max_event_size(&self) -> usize {
         self.values.limits.max_event_size.as_bytes()

relay-server/src/services/buffer/envelope_buffer/mod.rs

@@ -43,8 +43,8 @@ impl PolymorphicEnvelopeBuffer {
     /// Returns true if the implementation stores all envelopes in RAM.
     pub fn is_memory(&self) -> bool {
         match self {
-            PolymorphicEnvelopeBuffer::InMemory(_) => true,
-            PolymorphicEnvelopeBuffer::Sqlite(_) => false,
+            Self::InMemory(_) => true,
+            Self::Sqlite(_) => false,
         }
     }
 
@@ -183,13 +183,16 @@ impl PolymorphicEnvelopeBuffer {
         // Currently, we want to flush the buffer only for disk, since the in memory implementation
         // tries to not do anything and pop as many elements as possible within the shutdown
         // timeout.
-        let Self::Sqlite(buffer) = self else {
-            relay_log::trace!("PolymorphicEnvelopeBuffer: shutdown procedure not needed");
-            return false;
-        };
-        buffer.flush().await;
-
-        true
+        match self {
+            Self::Sqlite(buffer) if !buffer.stack_provider.ephemeral() => {
+                buffer.flush().await;
+                true
+            }
+            _ => {
+                relay_log::trace!("shutdown procedure not needed");
+                false
+            }
+        }
     }
 
     /// Returns the partition tag for this [`PolymorphicEnvelopeBuffer`].

relay-server/src/services/buffer/stack_provider/sqlite.rs

@@ -19,6 +19,7 @@ pub struct SqliteStackProvider {
     batch_size_bytes: usize,
     max_disk_size: usize,
     partition_id: u8,
+    ephemeral: bool,
 }
 
 #[warn(dead_code)]
@@ -31,9 +32,15 @@ impl SqliteStackProvider {
             batch_size_bytes: config.spool_envelopes_batch_size_bytes(),
             max_disk_size: config.spool_envelopes_max_disk_size(),
             partition_id,
+            ephemeral: config.spool_ephemeral(),
         })
     }
 
+    /// Returns `true` if data is stored on non-persistent disks.
+    pub fn ephemeral(&self) -> bool {
+        self.ephemeral
+    }
+
     /// Returns `true` when there might be data residing on disk, `false` otherwise.
     fn assume_data_on_disk(stack_creation_type: StackCreationType) -> bool {
         matches!(stack_creation_type, StackCreationType::Initialization)

tests/integration/test_basic.py

@@ -11,7 +11,8 @@
 from requests import HTTPError
 
 
-def test_graceful_shutdown_with_in_memory_buffer(mini_sentry, relay):
+@pytest.mark.parametrize("backend", ["memory", "disk"])
+def test_graceful_shutdown_with_ephemeral_buffer(mini_sentry, relay, backend):
     from time import sleep
 
     get_project_config_original = mini_sentry.app.view_functions["get_project_config"]
@@ -24,14 +25,21 @@ def get_project_config():
     project_id = 42
     mini_sentry.add_basic_project_config(project_id)
 
-    relay = relay(
-        mini_sentry,
-        {"limits": {"shutdown_timeout": 2}},
-    )
+    with tempfile.TemporaryDirectory() as db_dir:
+        db_file_path = (
+            os.path.join(db_dir, "database.db") if backend == "disk" else None
+        )
+        relay = relay(
+            mini_sentry,
+            {
+                "limits": {"shutdown_timeout": 5},
+                "spool": {"envelopes": {"path": db_file_path, "ephemeral": True}},
+            },
+        )
 
-    relay.send_event(project_id)
+        relay.send_event(project_id)
 
-    relay.shutdown(sig=signal.SIGTERM)
+        relay.shutdown(sig=signal.SIGTERM)
 
     # When using the memory envelope buffer, we optimistically do not do anything on shutdown, which means that the
     # buffer will try and pop as always as long as it can (within the shutdown timeout).