From 7121e8f51223c09fd9271ea2f742d89ebb1b871e Mon Sep 17 00:00:00 2001
From: Bart Koelman <104792814+bart-vmware@users.noreply.github.com>
Date: Fri, 12 Apr 2024 23:05:37 +0200
Subject: [PATCH] Prevent adding PlaceholderResolver multiple times, which
 breaks the ENV actuator (#1276)

---
 .../PlaceholderConfigurationExtensions.cs     | 24 ++++++++++-----
 .../PlaceholderConfigurationExtensionsTest.cs | 30 +++++++++++++++++++
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/src/Configuration/src/Placeholder/PlaceholderConfigurationExtensions.cs b/src/Configuration/src/Placeholder/PlaceholderConfigurationExtensions.cs
index 656ec341a0..b26d0c80da 100644
--- a/src/Configuration/src/Placeholder/PlaceholderConfigurationExtensions.cs
+++ b/src/Configuration/src/Placeholder/PlaceholderConfigurationExtensions.cs
@@ -48,15 +48,18 @@ public static IConfigurationBuilder AddPlaceholderResolver(this IConfigurationBu
         ArgumentGuard.NotNull(builder);
         ArgumentGuard.NotNull(loggerFactory);
 
-        if (builder is IConfigurationRoot configuration)
+        if (!builder.Sources.Any(source => source is PlaceholderResolverSource))
         {
-            builder.Add(new PlaceholderResolverSource(configuration, loggerFactory));
-        }
-        else
-        {
-            var resolver = new PlaceholderResolverSource(builder.Sources, loggerFactory);
-            builder.Sources.Clear();
-            builder.Add(resolver);
+            if (builder is IConfigurationRoot configuration)
+            {
+                builder.Add(new PlaceholderResolverSource(configuration, loggerFactory));
+            }
+            else
+            {
+                var resolver = new PlaceholderResolverSource(builder.Sources, loggerFactory);
+                builder.Sources.Clear();
+                builder.Add(resolver);
+            }
         }
 
         return builder;
@@ -102,6 +105,11 @@ public static IConfiguration AddPlaceholderResolver(this IConfiguration configur
             throw new InvalidOperationException($"Configuration must implement '{typeof(IConfigurationRoot)}'.");
         }
 
+        if (root.Providers.Any(provider => provider is IPlaceholderResolverProvider))
+        {
+            return configuration;
+        }
+
         return new ConfigurationRoot(new List<IConfigurationProvider>
         {
             new PlaceholderResolverProvider(new List<IConfigurationProvider>(root.Providers), loggerFactory)
diff --git a/src/Configuration/test/Placeholder.Test/PlaceholderConfigurationExtensionsTest.cs b/src/Configuration/test/Placeholder.Test/PlaceholderConfigurationExtensionsTest.cs
index c8cba16f30..5424866f02 100644
--- a/src/Configuration/test/Placeholder.Test/PlaceholderConfigurationExtensionsTest.cs
+++ b/src/Configuration/test/Placeholder.Test/PlaceholderConfigurationExtensionsTest.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+using FluentAssertions;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
 using Steeltoe.Common.Utils.IO;
@@ -22,6 +23,21 @@ public void AddPlaceholderResolver_AddsPlaceholderResolverSourceToList()
         Assert.NotNull(placeholderSource);
     }
 
+    [Fact]
+    public void AddPlaceholderResolver_NoDuplicates()
+    {
+        var configurationBuilder = new ConfigurationBuilder();
+
+        configurationBuilder.AddPlaceholderResolver();
+        configurationBuilder.AddPlaceholderResolver();
+        configurationBuilder.AddPlaceholderResolver();
+
+        PlaceholderResolverSource? source = configurationBuilder.Sources.OfType<PlaceholderResolverSource>().SingleOrDefault();
+        Assert.NotNull(source);
+        Assert.NotNull(source.Sources);
+        Assert.Empty(source.Sources);
+    }
+
     [Fact]
     public void AddPlaceholderResolver_CreatesProvider()
     {
@@ -251,4 +267,18 @@ public void AddPlaceholderResolver_WithConfiguration_ReturnsNewConfiguration()
         Assert.Equal("notfound", config2["key3"]);
         Assert.Equal("${nokey}", config2["key4"]);
     }
+
+    [Fact]
+    public void AddPlaceholderResolver_WithConfiguration_NoDuplicates()
+    {
+        IConfigurationRoot configurationRoot = new ConfigurationBuilder().Build();
+
+        IConfiguration newConfiguration = configurationRoot.AddPlaceholderResolver().AddPlaceholderResolver().AddPlaceholderResolver();
+
+        ConfigurationRoot newConfigurationRoot = newConfiguration.Should().BeOfType<ConfigurationRoot>().Which;
+        newConfigurationRoot.Providers.Should().HaveCount(1);
+
+        PlaceholderResolverProvider? provider = newConfigurationRoot.Providers.Single().Should().BeOfType<PlaceholderResolverProvider>().Which;
+        provider.Providers.Should().BeEmpty();
+    }
 }