Add abstract environment post processor for config data imports (#936)

spring-cloud-commons/src/main/java/org/springframework/cloud/commons/ConfigDataMissingEnvironmentPostProcessor.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2015-2021 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
+ *
+ *      https://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.cloud.commons;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.context.config.ConfigDataEnvironmentPostProcessor;
+import org.springframework.boot.context.properties.bind.Bindable;
+import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.boot.env.EnvironmentPostProcessor;
+import org.springframework.core.Ordered;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.Environment;
+
+/**
+ * @author Ryan Baxter
+ */
+public abstract class ConfigDataMissingEnvironmentPostProcessor implements EnvironmentPostProcessor, Ordered {
+
+	/**
+	 * Spring config import property name.
+	 */
+	public static final String CONFIG_IMPORT_PROPERTY = "spring.config.import";
+
+	private static final Bindable<String[]> CONFIG_DATA_LOCATION_ARRAY = Bindable.of(String[].class);
+
+	/**
+	 * Order of post processor, set to run after
+	 * {@link ConfigDataEnvironmentPostProcessor}.
+	 */
+	public static final int ORDER = ConfigDataEnvironmentPostProcessor.ORDER + 1000;
+
+	@Override
+	public int getOrder() {
+		return ORDER;
+	}
+
+	protected abstract boolean shouldProcessEnvironment(Environment environment);
+
+	protected abstract String getPrefix();
+
+	@Override
+	public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
+		if (!shouldProcessEnvironment(environment)) {
+			return;
+		}
+		List<String> property = getConfigImports(environment);
+		if (property == null || property.isEmpty()) {
+			throw new ImportException("No spring.config.import set", false);
+		}
+		if (!property.stream().anyMatch(impt -> impt.contains(getPrefix()))) {
+			throw new ImportException("spring.config.import missing " + getPrefix(), true);
+		}
+	}
+
+	private List<String> getConfigImports(ConfigurableEnvironment environment) {
+		List<String> property = environment.getProperty(CONFIG_IMPORT_PROPERTY, List.class);
+		if (property == null || property.isEmpty()) {
+			Binder binder = Binder.get(environment);
+			property = Arrays
+					.asList(binder.bind(CONFIG_IMPORT_PROPERTY, CONFIG_DATA_LOCATION_ARRAY).orElse(new String[0]));
+		}
+		return property;
+	}
+
+	public static class ImportException extends RuntimeException {
+
+		/**
+		 * Indicates if prefix is missing.
+		 */
+		public final boolean missingPrefix;
+
+		ImportException(String message, boolean missingPrefix) {
+			super(message);
+			this.missingPrefix = missingPrefix;
+		}
+
+	}
+
+}