Implement methods: getAdditionalProfileResources, checkPropertiesExist.

Add hard-coded requirements.
Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/java/com/fjordtek/bookstore/config/AdditionalPropertiesConfig.java

@@ -4,6 +4,7 @@ package com.fjordtek.bookstore.config;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import org.springframework.boot.SpringApplication;
@@ -24,6 +25,9 @@ import org.springframework.core.io.support.PropertiesLoaderUtils;
 * Main purpose of this implementation is to load additional properties files into Spring
 * environment as early as possible during Spring Boot initialization process.
 * <p>
+* Additionally, this class provides processing methods for Spring profile
+* properties configuration.
+* <p>
 * Loading of this class must be enabled in /resources/META-INF/spring.factories file.
 *
 * @author Pekka Helenius
@@ -33,15 +37,120 @@ import org.springframework.core.io.support.PropertiesLoaderUtils;
 //@Order(Ordered.LOWEST_PRECEDENCE)
 public class AdditionalPropertiesConfig implements EnvironmentPostProcessor {
 
+	// Add global properties
 	private List<Resource> getAdditionalResources() {
-		List<Resource> resources = new ArrayList<Resource>();
+		List<Resource> classPathResources = new ArrayList<Resource>();
 
-		// Add your additional (classpath, filesystem, etc.) properties files here
-		resources.add(new ClassPathResource("website.properties"));
-		resources.add(new ClassPathResource("authentication.properties"));
-		resources.add(new ClassPathResource("categories.properties"));
+		/*
+		 *  Add your additional global properties files here
+		 */
+		classPathResources.add(new ClassPathResource("website.properties"));
+		classPathResources.add(new ClassPathResource("authentication.properties"));
+		classPathResources.add(new ClassPathResource("categories.properties"));
+
+		return classPathResources;
+	}
+
+	// Add predefined profile properties
+	private List<Resource> getAdditionalProfileResources(String[] profiles) {
+		List<Resource> classPathResources = new ArrayList<Resource>();
+
+		/*
+		 * Add your additional profile property file prefixes here
+		 * For instance, if profile is 'dev':
+		 * "database" ->> "database-dev.properties"
+		 */
+		String[] resourceFilePrefixes = {
+				"database"
+		};
+
+		for (String profile : profiles) {
+
+			for (String prefix : resourceFilePrefixes) {
+				try {
+					ClassPathResource classPathResource = new ClassPathResource(prefix + "-" + profile + ".properties");
+					classPathResource.getFile().canRead();
+					classPathResources.add(classPathResource);
+					System.out.printf(
+							"Profile properties file found: %s\n",
+							classPathResource.getFilename()
+							);
+				} catch (IOException e) {
+
+					if ( prefix.equals("database") && profile.equals("prod") ) {
+
+						System.err.println(String.join("\n",
+								"Production mode was enabled. However the following issue occured.",
+								"",
+								"Missing file: database-prod.properties",
+								"",
+								"File is not found from application class path.",
+								"",
+								"Please provide the missing file with following entries:",
+								"",
+								"spring.datasource.driver-class-name                = com.mysql.cj.jdbc.Driver",
+								"spring.datasource.url                              = jdbc:mysql://<host_ip>:<TCP port>/<DB_DATABASE_NAME> ...",
+								"spring.datasource.username                         = <DB_USERNAME>",
+								"spring.datasource.password                         = <DB_PASSWORD>",
+								"spring.datasource.initialization-mode              = always",
+								"",
+								"spring.jpa.hibernate.use-new-id-generator-mappings = false",
+								"spring.jpa.hibernate.naming.physical-strategy      = org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl",
+								"",
+								"Unable to run application. Exiting."
+								)
+								);
+						System.exit(1);
+
+					} else {
+						System.err.println(
+							"Resource " +
+							prefix + "-" + profile + ".properties" +
+							" not found!"
+							);
+					}
+				}
+				continue;
+			}
+		}
+		return classPathResources;
+	}
+
+	private void checkPropertiesExist(
+			ConfigurableEnvironment environment,
+			String[] propEntries
+			) {
+
+		List<String> missingProperties = new ArrayList<String>();
+
+		for (String prop : propEntries) {
+			try {
+				environment.getRequiredProperty(prop);
+			} catch (IllegalStateException e) {
+				missingProperties.add(prop);
+			}
+		}
+
+		if (missingProperties.size() != 0) {
+			System.err.printf(
+					"\nFollowing, required application property entries are missing:\n\n"
+					);
+			int i = 0;
+			while (i < missingProperties.size()) {
+				System.err.printf(
+						"%s\n",
+						missingProperties.get(i)
+						);
+				i++;
+			}
+			System.err.printf(
+					"\nCannot continue. Exiting. (Active profiles: %s)\n",
+					Arrays.stream(environment.getActiveProfiles())
+						.toArray()
+					);
+			System.exit(1);
+		}
 
-		return resources;
 	}
 
 	private void showSpringConfiguration(MutablePropertySources properties) {
@@ -60,19 +169,41 @@ public class AdditionalPropertiesConfig implements EnvironmentPostProcessor {
 
 		MutablePropertySources propertySources = environment.getPropertySources();
 
-		for (Resource res : getAdditionalResources()) {
-			try {
-				propertySources.addLast(
-						new PropertiesPropertySource(
-								res.getFilename(),
-								PropertiesLoaderUtils.loadProperties(res)
-								)
-						);
-			} catch (IOException e) {
-				e.printStackTrace();
+		List<List<Resource>> additionalResources = new ArrayList<List<Resource>>();
+
+		additionalResources.add(getAdditionalResources());
+		additionalResources.add(getAdditionalProfileResources(environment.getActiveProfiles()));
+
+		for (List<Resource> resList : additionalResources) {
+			for (Resource res : resList) {
+				try {
+					propertySources.addLast(
+							new PropertiesPropertySource(
+									res.getFilename(),
+									PropertiesLoaderUtils.loadProperties(res)
+									)
+							);
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
 			}
 		}
 
+		if ( Arrays.stream(environment.getActiveProfiles()).anyMatch(p -> p.contains("prod")) ) {
+			checkPropertiesExist(
+					environment,
+					new String[] {
+							"spring.datasource.driver-class-name",
+							"spring.datasource.url",
+							"spring.datasource.username",
+							"spring.datasource.password",
+							"spring.datasource.initialization-mode",
+							"spring.jpa.hibernate.use-new-id-generator-mappings",
+							"spring.jpa.hibernate.naming.physical-strategy"
+					}
+					);
+		}
+
 		showSpringConfiguration(propertySources);
 	}