From 82b919c8f426c70b2a38512d1a4d4ce694e76954 Mon Sep 17 00:00:00 2001
From: Scott Balmos <399112+sbalmos@users.noreply.github.com>
Date: Sun, 21 Sep 2025 16:16:15 -0400
Subject: [PATCH 1/2] Implement proper indexer ack query compression in
 `splunk_hec` sinks

---
 .../splunk_hec/common/acknowledgements.rs     | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/sinks/splunk_hec/common/acknowledgements.rs b/src/sinks/splunk_hec/common/acknowledgements.rs
index 5fc0ab568823f..6975653a8b2fc 100644
--- a/src/sinks/splunk_hec/common/acknowledgements.rs
+++ b/src/sinks/splunk_hec/common/acknowledgements.rs
@@ -1,16 +1,17 @@
+use hyper::Body;
+use serde::{Deserialize, Serialize};
+use std::io::Write;
 use std::{
     collections::HashMap,
     num::{NonZeroU8, NonZeroU64},
     sync::Arc,
     time::Duration,
 };
-
-use hyper::Body;
-use serde::{Deserialize, Serialize};
 use tokio::sync::{mpsc::Receiver, oneshot::Sender};
 use vector_lib::{configurable::configurable_component, event::EventStatus};
 
 use super::service::{HttpRequestBuilder, MetadataFields};
+use crate::sinks::util::Compressor;
 use crate::{
     config::AcknowledgementsConfig,
     http::HttpClient,
@@ -18,7 +19,6 @@ use crate::{
         SplunkIndexerAcknowledgementAPIError, SplunkIndexerAcknowledgementAckAdded,
         SplunkIndexerAcknowledgementAcksRemoved,
     },
-    sinks::util::Compression,
 };
 
 /// Splunk HEC acknowledgement configuration.
@@ -96,12 +96,6 @@ impl HecAckClient {
         client: HttpClient,
         http_request_builder: Arc<HttpRequestBuilder>,
     ) -> Self {
-        // Reimplement with compression support, see https://github.com/vectordotdev/vector/issues/23748
-        let http_request_builder = Arc::new(HttpRequestBuilder {
-            compression: Compression::None,
-            ..(*http_request_builder).clone()
-        });
-
         Self {
             acks: HashMap::new(),
             retry_limit,
@@ -222,10 +216,18 @@ impl HecAckClient {
         let request_body_bytes = crate::serde::json::to_bytes(request_body)
             .map_err(|_| HecAckApiError::ClientBuildRequest)?
             .freeze();
+        let mut compressor = Compressor::from(self.http_request_builder.compression);
+        compressor
+            .write_all(request_body_bytes.as_ref())
+            .map_err(|_| HecAckApiError::ClientBuildRequest)?;
+        let payload = compressor
+            .finish()
+            .map_err(|_| HecAckApiError::ClientBuildRequest)?
+            .freeze();
         let request = self
             .http_request_builder
             .build_request(
-                request_body_bytes,
+                payload,
                 "/services/collector/ack",
                 None,
                 MetadataFields::default(),

From 64c50063a2bd8994ee3c21e9b89744a9f38e77cf Mon Sep 17 00:00:00 2001
From: Scott Balmos <399112+sbalmos@users.noreply.github.com>
Date: Sun, 21 Sep 2025 16:23:34 -0400
Subject: [PATCH 2/2] Changelog fragment

---
 changelog.d/23748_add_indexer_ack_compression.feature.md | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 changelog.d/23748_add_indexer_ack_compression.feature.md

diff --git a/changelog.d/23748_add_indexer_ack_compression.feature.md b/changelog.d/23748_add_indexer_ack_compression.feature.md
new file mode 100644
index 0000000000000..5b9068623a09a
--- /dev/null
+++ b/changelog.d/23748_add_indexer_ack_compression.feature.md
@@ -0,0 +1,3 @@
+Adds proper support for compression of HEC indexer ack queries, using the sink's configured `compression` setting.
+
+authors: sbalmos