From ff37635ed09e1d9b198687172752a1aba7459c1e Mon Sep 17 00:00:00 2001
From: phlax <phlax@users.noreply.github.com>
Date: Sun, 16 Apr 2023 22:58:57 +0100
Subject: [PATCH] ci: Dont stamp Envoy binary in Pull Requests (#26776)

Fix #26632

Signed-off-by: Ryan Northey <ryan@synca.io>
---
 .azure-pipelines/bazel.yml |  3 +++
 .bazelrc                   |  4 ++++
 bazel/get_workspace_status | 13 +++++++++----
 ci/run_envoy_docker.sh     |  1 +
 4 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/.azure-pipelines/bazel.yml b/.azure-pipelines/bazel.yml
index 0963e825e8d8..fd3af0d60c55 100644
--- a/.azure-pipelines/bazel.yml
+++ b/.azure-pipelines/bazel.yml
@@ -98,6 +98,9 @@ steps:
       AZP_TARGET_BRANCH: "origin/$(System.PullRequest.TargetBranch)"
     ${{ if ne(variables['Build.Reason'], 'PullRequest') }}:
       AZP_TARGET_BRANCH: "origin/$(Build.SourceBranchName)"
+    ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
+      # sha1sum of `ENVOY_PULL_REQUEST`
+      BAZEL_FAKE_SCM_REVISION: e3b4a6e9570da15ac1caffdded17a8bebdc7dfc9
     ${{ if parameters.rbe }}:
       GCP_SERVICE_ACCOUNT_KEY: $(GcpServiceAccountKey)
       ENVOY_RBE: "1"
diff --git a/.bazelrc b/.bazelrc
index 44716f4baa91..695c1bd2eb00 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -33,6 +33,10 @@ build --action_env=PATH --host_action_env=PATH
 # Requires setting `BAZEL_VOLATILE_DIRTY` in the env.
 build --action_env=BAZEL_VOLATILE_DIRTY --host_action_env=BAZEL_VOLATILE_DIRTY
 
+# Prevent stamped caches from busting (eg in PRs)
+# Requires setting `BAZEL_FAKE_SCM_REVISION` in the env.
+build --action_env=BAZEL_FAKE_SCM_REVISION --host_action_env=BAZEL_FAKE_SCM_REVISION
+
 build --enable_platform_specific_config
 build --test_summary=terse
 
diff --git a/bazel/get_workspace_status b/bazel/get_workspace_status
index 203f23fde0c4..ca5159e6dea9 100755
--- a/bazel/get_workspace_status
+++ b/bazel/get_workspace_status
@@ -28,10 +28,15 @@ then
     exit 0
 fi
 
-# The code below presents an implementation that works for git repository
-git_rev=$(git rev-parse HEAD) || exit 1
-echo "BUILD_SCM_REVISION ${git_rev}"
-echo "STABLE_BUILD_SCM_REVISION ${git_rev}"
+if [[ -n "$BAZEL_FAKE_SCM_REVISION" ]]; then
+    echo "BUILD_SCM_REVISION $BAZEL_FAKE_SCM_REVISION"
+    echo "STABLE_BUILD_SCM_REVISION $BAZEL_FAKE_SCM_REVISION"
+else
+    # The code below presents an implementation that works for git repository
+    git_rev=$(git rev-parse HEAD) || exit 1
+    echo "BUILD_SCM_REVISION ${git_rev}"
+    echo "STABLE_BUILD_SCM_REVISION ${git_rev}"
+fi
 
 # If BAZEL_VOLATILE_DIRTY is set then stamped builds will rebuild uncached when
 # either a tracked file changes or an untracked file is added or removed.
diff --git a/ci/run_envoy_docker.sh b/ci/run_envoy_docker.sh
index 3be3ec31c7bc..f4c93673f161 100755
--- a/ci/run_envoy_docker.sh
+++ b/ci/run_envoy_docker.sh
@@ -103,6 +103,7 @@ docker run --rm \
        -e BAZEL_STARTUP_OPTIONS \
        -e BAZEL_BUILD_EXTRA_OPTIONS \
        -e BAZEL_EXTRA_TEST_OPTIONS \
+       -e BAZEL_FAKE_SCM_REVISION \
        -e BAZEL_REMOTE_CACHE \
        -e ENVOY_STDLIB \
        -e BUILD_REASON \