From a5ed07a666145fc5d9d46da2455ce0625fc45868 Mon Sep 17 00:00:00 2001
From: Chris Eager <chris@signal.org>
Date: Thu, 18 Jan 2024 17:06:38 -0600
Subject: [PATCH] Support environment variable substitution in configuration

---
 .../textsecuregcm/WhisperServerService.java              | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
index fc5d69248..22e9b3f7d 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
@@ -13,6 +13,8 @@ import io.dropwizard.auth.AuthFilter;
 import io.dropwizard.auth.AuthValueFactoryProvider;
 import io.dropwizard.auth.basic.BasicCredentialAuthFilter;
 import io.dropwizard.auth.basic.BasicCredentials;
+import io.dropwizard.configuration.EnvironmentVariableSubstitutor;
+import io.dropwizard.configuration.SubstitutingSourceProvider;
 import io.dropwizard.core.Application;
 import io.dropwizard.core.server.DefaultServerFactory;
 import io.dropwizard.core.setup.Bootstrap;
@@ -260,6 +262,13 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     // Initializing SystemMapper here because parsing of the main application config happens before `run()` method is called.
     SystemMapper.configureMapper(bootstrap.getObjectMapper());
 
+    // Enable variable substitution with environment variables
+    // https://www.dropwizard.io/en/stable/manual/core.html#environment-variables
+    final EnvironmentVariableSubstitutor substitutor = new EnvironmentVariableSubstitutor(true);
+    final SubstitutingSourceProvider provider =
+        new SubstitutingSourceProvider(bootstrap.getConfigurationSourceProvider(), substitutor);
+    bootstrap.setConfigurationSourceProvider(provider);
+
     bootstrap.addCommand(new DeleteUserCommand());
     bootstrap.addCommand(new CertificateCommand());
     bootstrap.addCommand(new ZkParamsCommand());