From 1a990f2aa9281625852a5857e7904d4a2d41d8dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9o=20Babut?=
 <38383681+balobe@users.noreply.github.com>
Date: Fri, 10 Jul 2026 20:41:28 +0200
Subject: [PATCH] docs(website): document valid character restrictions for env
 var interpolation

---
 website/content/en/docs/reference/environment_variables.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/website/content/en/docs/reference/environment_variables.md b/website/content/en/docs/reference/environment_variables.md
index 177231095313c..06db13e50a2e2 100644
--- a/website/content/en/docs/reference/environment_variables.md
+++ b/website/content/en/docs/reference/environment_variables.md
@@ -57,6 +57,11 @@ You can escape environment variables by prefacing them with a `$` character. For
 example `$${HOSTNAME}` or `$$HOSTNAME` is treated literally in the above
 environment variable example.
 
+## Variable name restrictions
+
+Environment variable names used in interpolation are restricted to letters, digits plus `_`  and `.` characters. 
+Names containing other characters (such as hyphens `-`) will not be interpolated.
+
 ## Security Restrictions
 
 Vector prevents security issues related to environment variable interpolation by rejecting environment variables that contain newline