ci: forward BP_EXTERNAL_S3_URL through benchmark triggers

.gitlab-ci.yml

@@ -8,6 +8,10 @@ stages:
   - release
 
 variables:
+  # Benchmark trigger jobs forward $BP_EXTERNAL_S3_URL to downstream pipelines so
+  # an external orchestrator can override the S3 destination of benchmark results.
+  # Defaulted to empty here so an unset value forwards as "" rather than a literal.
+  BP_EXTERNAL_S3_URL: ""
   REPO_LANG: python # "python" is used everywhere rather than "py"
   REPO_NOTIFICATION_CHANNEL: "#apm-python-release"
   RELEASE_ALLOW_TEST_FAILURES: false
@@ -186,6 +190,8 @@ microbenchmarks:
     PARENT_PIPELINE_ID: $CI_PIPELINE_ID
     # Disable VPA for benchmarks
     DD_DISABLE_VPA: true
+    # Forward the external S3 destination override to the benchmark child pipeline.
+    BP_EXTERNAL_S3_URL: $BP_EXTERNAL_S3_URL
 
 apm-sdk-benchmarks:
   stage: benchmarks
@@ -214,6 +220,8 @@ macrobenchmarks:
     PARENT_PIPELINE_ID: $CI_PIPELINE_ID
     # Disable VPA for benchmarks
     DD_DISABLE_VPA: true
+    # Forward the external S3 destination override to the benchmark child pipeline.
+    BP_EXTERNAL_S3_URL: $BP_EXTERNAL_S3_URL
   allow_failure: false
   rules:
     # Always run on nightly schedule or API triggered pipelines