Ignore unbound env variables and system props

Closes gh-3832

spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

@@ -43,6 +43,7 @@ import org.springframework.boot.context.properties.bind.handler.NoUnboundElement
 import org.springframework.boot.context.properties.bind.validation.ValidationBindHandler;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
+import org.springframework.boot.context.properties.source.UnboundElementsSourceFilter;
 import org.springframework.boot.validation.MessageInterpolatorFactory;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
@@ -420,7 +421,8 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 			handler = new IgnoreErrorsBindHandler(handler);
 		}
 		if (!annotation.ignoreUnknownFields()) {
-			handler = new NoUnboundElementsBindHandler(handler);
+			UnboundElementsSourceFilter filter = new UnboundElementsSourceFilter();
+			handler = new NoUnboundElementsBindHandler(handler, filter);
 		}
 		if (validator != null) {
 			handler = new ValidationBindHandler(handler, validator);

spring-boot/src/main/java/org/springframework/boot/context/properties/bind/handler/NoUnboundElementsBindHandler.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.bind.handler;
 import java.util.HashSet;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.function.Function;
 
 import org.springframework.boot.context.properties.bind.AbstractBindHandler;
 import org.springframework.boot.context.properties.bind.BindContext;
@@ -42,12 +43,19 @@ public class NoUnboundElementsBindHandler extends AbstractBindHandler {
 
 	private final Set<ConfigurationPropertyName> boundNames = new HashSet<>();
 
+	private final Function<ConfigurationPropertySource, Boolean> filter;
+
 	NoUnboundElementsBindHandler() {
-		super();
+		this(BindHandler.DEFAULT, (configurationPropertySource) -> true);
 	}
 
 	public NoUnboundElementsBindHandler(BindHandler parent) {
+		this(parent, (configurationPropertySource) -> true);
+	}
+
+	public NoUnboundElementsBindHandler(BindHandler parent, Function<ConfigurationPropertySource, Boolean> filter) {
 		super(parent);
+		this.filter = filter;
 	}
 
 	@Override
@@ -69,7 +77,7 @@ public class NoUnboundElementsBindHandler extends AbstractBindHandler {
 			BindContext context) {
 		Set<ConfigurationProperty> unbound = new TreeSet<>();
 		for (ConfigurationPropertySource source : context.getSources()) {
-			if (source instanceof IterableConfigurationPropertySource) {
+			if (this.filter.apply(source)) {
 				collectUnbound(name, unbound,
 						(IterableConfigurationPropertySource) source);
 			}

spring-boot/src/main/java/org/springframework/boot/context/properties/source/AliasedConfigurationPropertySource.java

@@ -68,6 +68,11 @@ class AliasedConfigurationPropertySource implements ConfigurationPropertySource
 		return ConfigurationPropertyState.ABSENT;
 	}
 
+	@Override
+	public Object getUnderlyingSource() {
+		return this.source.getUnderlyingSource();
+	}
+
 	protected ConfigurationPropertySource getSource() {
 		return this.source;
 	}

spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySource.java

@@ -72,4 +72,10 @@ public interface ConfigurationPropertySource {
 		return new AliasedConfigurationPropertySource(this, aliases);
 	}
 
+	/**
+	 * Return the underlying {@PropertySource}.
+	 * @return the underlying property source.
+	 */
+	Object getUnderlyingSource();
+
 }

spring-boot/src/main/java/org/springframework/boot/context/properties/source/FilteredConfigurationPropertiesSource.java

@@ -58,6 +58,11 @@ class FilteredConfigurationPropertiesSource implements ConfigurationPropertySour
 		return result;
 	}
 
+	@Override
+	public Object getUnderlyingSource() {
+		return this.source.getUnderlyingSource();
+	}
+
 	protected ConfigurationPropertySource getSource() {
 		return this.source;
 	}

spring-boot/src/main/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySource.java

@@ -78,6 +78,11 @@ public class MapConfigurationPropertySource
 		this.source.put((name == null ? null : name.toString()), value);
 	}
 
+	@Override
+	public Object getUnderlyingSource() {
+		return this.source;
+	}
+
 	@Override
 	public ConfigurationProperty getConfigurationProperty(
 			ConfigurationPropertyName name) {

spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySource.java

@@ -94,6 +94,11 @@ class SpringConfigurationPropertySource implements ConfigurationPropertySource {
 		return this.containsDescendantOfMethod.apply(name);
 	}
 
+	@Override
+	public Object getUnderlyingSource() {
+		return this.propertySource;
+	}
+
 	protected final ConfigurationProperty find(List<PropertyMapping> mappings,
 			ConfigurationPropertyName name) {
 		return mappings.stream().filter((m) -> m.isApplicable(name)).map(this::find)

spring-boot/src/main/java/org/springframework/boot/context/properties/source/UnboundElementsSourceFilter.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.context.properties.source;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.Function;
+
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.env.StandardEnvironment;
+
+/**
+ * Function used to determine if a {@link ConfigurationPropertySource} should be
+ * included when determining unbound elements. If the underlying {@link PropertySource}
+ * is a systemEnvironment or systemProperties property source , it will not be considered
+ * for unbound element failures.
+ *
+ * @author Madhura Bhave
+ * @since 2.0.0
+ */
+public class UnboundElementsSourceFilter implements Function<ConfigurationPropertySource, Boolean> {
+
+	private static final Set<String> BENIGN_PROPERTY_SOURCE_NAMES = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
+			StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME,
+			StandardEnvironment.SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME)));
+
+	@Override
+	public Boolean apply(ConfigurationPropertySource configurationPropertySource) {
+		Object underlyingSource = configurationPropertySource.getUnderlyingSource();
+		if (underlyingSource instanceof PropertySource) {
+			String name = ((PropertySource) underlyingSource).getName();
+			return !BENIGN_PROPERTY_SOURCE_NAMES.contains(name);
+
+		}
+		return true;
+	}
+
+}
+

spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessorTests.java

@@ -419,6 +419,21 @@ public class ConfigurationPropertiesBindingPostProcessorTests {
 		assertThat(foo).isEqualTo(10);
 	}
 
+	@Test
+	public void unboundElementsFromSystemEnvironmentShouldNotThrowException() throws Exception {
+		this.context = new AnnotationConfigApplicationContext();
+		ConfigurableEnvironment env = this.context.getEnvironment();
+		MutablePropertySources propertySources = env.getPropertySources();
+		propertySources.addFirst(new MapPropertySource("test",
+				Collections.singletonMap("com.example.foo", 5)));
+		propertySources.addLast(new SystemEnvironmentPropertySource("system",
+				Collections.singletonMap("COM_EXAMPLE_OTHER", "10")));
+		this.context.register(TestConfiguration.class);
+		this.context.refresh();
+		int foo = this.context.getBean(TestConfiguration.class).getFoo();
+		assertThat(foo).isEqualTo(5);
+	}
+
 	@Test
 	public void rebindableConfigurationProperties() throws Exception {
 		// gh-9160

spring-boot/src/test/java/org/springframework/boot/context/properties/bind/handler/NoUnboundElementsBindHandlerTests.java

@@ -24,6 +24,7 @@ import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
 import org.springframework.boot.context.properties.bind.BindException;
+import org.springframework.boot.context.properties.bind.BindHandler;
 import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
@@ -103,6 +104,20 @@ public class NoUnboundElementsBindHandlerTests {
 		assertThat(bound.getFoo()).isEqualTo("bar");
 	}
 
+	@Test
+	public void bindWhenUsingNoUnboundElementsHandlerShouldBindIfUnboundSystemProperties()
+			throws Exception {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("example.foo", "bar");
+		source.put("example.other", "baz");
+		this.sources.add(source);
+		this.binder = new Binder(this.sources);
+		NoUnboundElementsBindHandler handler = new NoUnboundElementsBindHandler(BindHandler.DEFAULT, (configurationPropertySource -> false));
+		Example bound = this.binder.bind("example", Bindable.of(Example.class),
+				handler).get();
+		assertThat(bound.getFoo()).isEqualTo("bar");
+	}
+
 	public static class Example {
 
 		private String foo;

spring-boot/src/test/java/org/springframework/boot/context/properties/source/MockConfigurationPropertySource.java

@@ -75,6 +75,11 @@ public class MockConfigurationPropertySource
 		return this.map.keySet().stream();
 	}
 
+	@Override
+	public Object getUnderlyingSource() {
+		return this.map;
+	}
+
 	@Override
 	public ConfigurationProperty getConfigurationProperty(
 			ConfigurationPropertyName name) {
@@ -91,6 +96,11 @@ public class MockConfigurationPropertySource
 
 	private class NonIterable implements ConfigurationPropertySource {
 
+		@Override
+		public Object getUnderlyingSource() {
+			return MockConfigurationPropertySource.this.map;
+		}
+
 		@Override
 		public ConfigurationProperty getConfigurationProperty(
 				ConfigurationPropertyName name) {

spring-boot/src/test/java/org/springframework/boot/context/properties/source/UnboundElementsSourceFilterTests.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.context.properties.source;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.core.env.StandardEnvironment;
+import org.springframework.mock.env.MockPropertySource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link UnboundElementsSourceFilter}.
+ *
+ * @author Madhura Bhave
+ */
+public class UnboundElementsSourceFilterTests {
+
+	private UnboundElementsSourceFilter filter;
+
+	private ConfigurationPropertySource source;
+
+	@Before
+	public void setUp() throws Exception {
+		this.filter = new UnboundElementsSourceFilter();
+		this.source = mock(ConfigurationPropertySource.class);
+	}
+
+	@Test
+	public void filterWhenSourceIsSystemEnvironmentPropertySourceShouldReturnFalse() throws Exception {
+		MockPropertySource propertySource = new MockPropertySource(StandardEnvironment.SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME);
+		given(this.source.getUnderlyingSource()).willReturn(propertySource);
+		assertThat(this.filter.apply(this.source)).isFalse();
+	}
+
+	@Test
+	public void filterWhenSourceIsSystemPropertiesPropertySourceShouldReturnTrue() throws Exception {
+		MockPropertySource propertySource = new MockPropertySource(StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME);
+		given(this.source.getUnderlyingSource()).willReturn(propertySource);
+		assertThat(this.filter.apply(this.source)).isFalse();
+	}
+
+	@Test
+	public void filterWhenSourceIsNotSystemShouldReturnTrue() throws Exception {
+		MockPropertySource propertySource = new MockPropertySource("test");
+		given(this.source.getUnderlyingSource()).willReturn(propertySource);
+		assertThat(this.filter.apply(this.source)).isTrue();
+	}
+
+}