From 93f312d95b9ded74ab55ce655de95e4a720d40eb Mon Sep 17 00:00:00 2001
From: "update-envoy[bot]"
 <135279899+update-envoy[bot]@users.noreply.github.com>
Date: Fri, 1 Sep 2023 06:46:32 +0000
Subject: [PATCH] http: added OVERWRITE_IF_EXISTS header manipulator (#27923)

This is to address a use case when a header should be modified only when it exists and should not be added when it does not exist.

Risk Level: Low
Testing: Unit tests.
Docs Changes: Yes.
Release Notes: Yes
Platform Specific Features: No

Fixes #27907

Signed-off-by: Christoph Pakulski <christoph@tetrate.io>

Mirrored from https://github.com/envoyproxy/envoy @ d9ba9d17016296c50069584905dee1a19427d42e
---
 envoy/config/core/v3/base.proto | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/envoy/config/core/v3/base.proto b/envoy/config/core/v3/base.proto
index 859fcbae..f84e168b 100644
--- a/envoy/config/core/v3/base.proto
+++ b/envoy/config/core/v3/base.proto
@@ -359,6 +359,10 @@ message HeaderValueOption {
     // the header already exists. If the header doesn't exist then this will add the header
     // with specified key and value.
     OVERWRITE_IF_EXISTS_OR_ADD = 2;
+
+    // This action will overwrite the specified value by discarding any existing values if
+    // the header already exists. If the header doesn't exist then this will be no-op.
+    OVERWRITE_IF_EXISTS = 3;
   }
 
   // Header name/value pair that this option applies to.