From 8938a094342e91bf25b946cc94884affd7aa5cd3 Mon Sep 17 00:00:00 2001
From: c04x <raif.trek@gmail.com>
Date: Mon, 5 Feb 2024 16:18:19 +0100
Subject: [PATCH] Fix for multiple env vars in config parameters

---
 .../plugins/ConfigVariableExpander.java       | 12 ++++++++--
 .../common/ConfigVariableExpanderTest.java    | 22 +++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/logstash-core/src/main/java/org/logstash/plugins/ConfigVariableExpander.java b/logstash-core/src/main/java/org/logstash/plugins/ConfigVariableExpander.java
index 008ddc599d6..9e8bd4d23ba 100644
--- a/logstash-core/src/main/java/org/logstash/plugins/ConfigVariableExpander.java
+++ b/logstash-core/src/main/java/org/logstash/plugins/ConfigVariableExpander.java
@@ -82,9 +82,17 @@ public Object expand(Object value, boolean keepSecrets) {
         String variable = (String) value;
 
         Matcher m = substitutionPattern.matcher(variable);
-        if (!m.matches()) {
-            return variable;
+
+        if (m.matches()) {
+            return replaceMatchedVariables(keepSecrets, m, variable);
+        } else if (m.find()) {
+            return m.replaceAll(matchResult -> replaceMatchedVariables(false, m, variable).toString());
         }
+
+        return variable;
+    }
+
+    private Object replaceMatchedVariables(boolean keepSecrets, Matcher m, String variable) {
         String variableName = m.group("name");
 
         if (secretStore != null) {
diff --git a/logstash-core/src/test/java/org/logstash/common/ConfigVariableExpanderTest.java b/logstash-core/src/test/java/org/logstash/common/ConfigVariableExpanderTest.java
index 0b111308f3d..81640033b5a 100644
--- a/logstash-core/src/test/java/org/logstash/common/ConfigVariableExpanderTest.java
+++ b/logstash-core/src/test/java/org/logstash/common/ConfigVariableExpanderTest.java
@@ -61,6 +61,28 @@ public void testSimpleExpansion() throws Exception {
         Assert.assertEquals(val, expandedValue);
     }
 
+    @Test
+    public void testPartialExpansion() throws Exception {
+        String key = "foo";
+        String val = "bar";
+        ConfigVariableExpander cve = getFakeCve(Collections.emptyMap(), Collections.singletonMap(key, val));
+
+        String expandedValue = (String) cve.expand("test_partial_${" + key + "}");
+        Assert.assertEquals("test_partial_"+val, expandedValue);
+    }
+
+    @Test
+    public void testTwoExpansions() throws Exception {
+        String key1 = "foo";
+        String key2 = "bar";
+        String val1 = "foo_val";
+        String val2 = "bar_val";
+        ConfigVariableExpander cve = getFakeCve(Collections.emptyMap(), Map.of(key1, val1, key2, val2));
+
+        String expandedValue = (String) cve.expand("${" + key1 + "}${" + key2 + "}");
+        Assert.assertEquals(val1+val2, expandedValue);
+    }
+
     @Test
     public void testExpansionWithDefaultValue() throws Exception {
         String key = "foo";