From 37d6690d9b6556cceef005465d810c1325786945 Mon Sep 17 00:00:00 2001
From: Daniel Mitterdorfer <danielmitterdorfer@users.noreply.github.com>
Date: Thu, 7 Dec 2023 10:07:37 +0100
Subject: [PATCH] Always allow sample size for stacktraces (#103101)

The profiling get stacktraces API can be used in two different places:

1. In the native profiling UI
2. From within an APM context

In the latter case we disallowed the `sample_size` request body
parameter because the implementation always considers all samples.
However, as this will change in the future and we need to accept the
`sample_size` parameter this will lead to rejected requests during
upgrades. With this commit we always accept the `sample_size` request
body parameter to avoid such cases.
---
 .../xpack/profiling/GetStackTracesRequest.java  |  9 +--------
 .../profiling/GetStackTracesRequestTests.java   | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/GetStackTracesRequest.java b/x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/GetStackTracesRequest.java
index 3ab797e4b16ad..f81b5f01caae3 100644
--- a/x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/GetStackTracesRequest.java
+++ b/x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/GetStackTracesRequest.java
@@ -247,13 +247,6 @@ public ActionRequestValidationException validate() {
                     validationException
                 );
             }
-            // we don't do downsampling when a custom index is provided
-            if (sampleSize != null) {
-                validationException = addValidationError(
-                    "[" + SAMPLE_SIZE_FIELD.getPreferredName() + "] must not be set",
-                    validationException
-                );
-            }
         } else {
             if (stackTraceIds != null) {
                 validationException = addValidationError(
@@ -261,8 +254,8 @@ public ActionRequestValidationException validate() {
                     validationException
                 );
             }
-            validationException = requirePositive(SAMPLE_SIZE_FIELD, sampleSize, validationException);
         }
+        validationException = requirePositive(SAMPLE_SIZE_FIELD, sampleSize, validationException);
         validationException = requirePositive(REQUESTED_DURATION_FIELD, requestedDuration, validationException);
         validationException = requirePositive(AWS_COST_FACTOR_FIELD, awsCostFactor, validationException);
         validationException = requirePositive(CUSTOM_CO2_PER_KWH, customCO2PerKWH, validationException);
diff --git a/x-pack/plugin/profiling/src/test/java/org/elasticsearch/xpack/profiling/GetStackTracesRequestTests.java b/x-pack/plugin/profiling/src/test/java/org/elasticsearch/xpack/profiling/GetStackTracesRequestTests.java
index 5b6befbe5a2c2..8bf4598cf75f7 100644
--- a/x-pack/plugin/profiling/src/test/java/org/elasticsearch/xpack/profiling/GetStackTracesRequestTests.java
+++ b/x-pack/plugin/profiling/src/test/java/org/elasticsearch/xpack/profiling/GetStackTracesRequestTests.java
@@ -170,6 +170,23 @@ public void testValidateWrongSampleSize() {
         assertTrue(validationErrors.get(0).contains("[sample_size] must be greater than 0,"));
     }
 
+    public void testValidateSampleSizeIsValidWithCustomIndices() {
+        GetStackTracesRequest request = new GetStackTracesRequest(
+            10,
+            1.0d,
+            1.0d,
+            null,
+            randomAlphaOfLength(7),
+            randomAlphaOfLength(3),
+            null,
+            null,
+            null,
+            null,
+            null
+        );
+        assertNull("Expecting no validation errors", request.validate());
+    }
+
     public void testValidateStacktraceWithoutIndices() {
         GetStackTracesRequest request = new GetStackTracesRequest(
             1,