From 981756b45699d376a9706554be4f6b406c4552eb Mon Sep 17 00:00:00 2001
From: Dane Everitt <dane@daneeveritt.com>
Date: Sun, 24 Oct 2021 15:20:27 -0700
Subject: [PATCH] Support escaping dollar signs in the YAML config file; closes
 pterodactyl/panel#3692

---
 config/config.go | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/config/config.go b/config/config.go
index 07b6a74..a75befb 100644
--- a/config/config.go
+++ b/config/config.go
@@ -457,9 +457,22 @@ func FromFile(path string) error {
 		return err
 	}
 	// Replace environment variables within the configuration file with their
-	// values from the host system.
-	b = []byte(os.ExpandEnv(string(b)))
-	if err := yaml.Unmarshal(b, c); err != nil {
+	// values from the host system. This function works almost identically to
+	// the default os.ExpandEnv function, except it supports escaping dollar
+	// signs in the text if you pass "$$" through.
+	//
+	// "some$$foo" -> "some$foo"
+	// "some$foo" -> "some" (or "someVALUE_OF_FOO" if FOO is defined in env)
+	//
+	// @see https://github.com/pterodactyl/panel/issues/3692
+	exp := os.Expand(string(b), func(s string) string {
+		if s == "$" {
+			return s
+		}
+		return os.Getenv(s)
+	})
+
+	if err := yaml.Unmarshal([]byte(exp), c); err != nil {
 		return err
 	}
 	// Store this configuration in the global state.