Ws2020 docker (dirkriehle#6)

* Add Dockerfile
* Extend DatabaseConnection with method to wait for db
* Adjust AbstractMain to check DB connection
* Add Wahlzeit app to docker-compose
* Adjust Dockefile
* Refactor AbstractMain to throw runtime error if db is not abailable.
* Extend JavaDoc of DatabaseConnection

Dockerfile

@@ -0,0 +1,34 @@
+#########################################################
+# First stage: image to build the application           #
+#########################################################
+FROM adoptopenjdk/openjdk11-openj9:alpine-slim as builder
+
+WORKDIR /builder
+
+# Copy Gradle file
+COPY *.gradle /builder/
+
+# Copy sources
+COPY src /builder/src
+
+# Copy Gradle resources
+COPY gradle /builder/gradle
+COPY gradlew /builder/gradlew
+
+# Test project
+RUN ./gradlew test
+
+# Build project 
+RUN ./gradlew assemble
+
+#########################################################
+# Second stage: image to run the application            #
+#########################################################
+FROM jetty:9.4-jre11-slim
+
+
+# Pull the built files from the builder container
+COPY --from=builder /builder/build/libs/*.war /var/lib/jetty/webapps/wahlzeit.war
+
+# Expose port
+EXPOSE 8080

docker-compose.yml

@@ -1,6 +1,14 @@
 version: '3.7'
 
 services:
+  app: 
+    image: wahlzeit
+    build:
+      context: .
+    environment: 
+      WAHLZEIT_DB_HOST: "db"
+    ports: 
+      - 8080:8080
   db:
     image: postgres:12-alpine
     environment:

src/main/java/org/wahlzeit/main/AbstractMain.java

@@ -20,13 +20,17 @@
 
 package org.wahlzeit.main;
 
+import java.util.Optional;
+
 import org.wahlzeit.services.*;
 
 /**
  * A superclass for a Main class for system startup and shutdown.
  */
 public abstract class AbstractMain {
 
+	private static final String DB_HOST = Optional.ofNullable(System.getenv("WAHLZEIT_DB_HOST")).orElse("localhost");
+
 	/**
 	 * 
 	 */
@@ -43,32 +47,17 @@ protected AbstractMain() {
 	 * 
 	 */
 	protected void startUp(String rootDir) throws Exception {
-		SysConfig.setInstance(createSysConfig(rootDir));
+		SysConfig.setInstance(new SysConfig(rootDir, DB_HOST));
 
+		boolean dbAvailable = DatabaseConnection.waitForDatabaseIsReady(30, 1000);
+		if (!dbAvailable) {
+			throw new RuntimeException("Unable to proceed with wahlzeit app. DB connection could not be established.");
+		}		
+
 		mainSession = new SysSession("system");
 		SessionManager.setThreadLocalSession(mainSession);
 	}
 
-	/**
-	 * 
-	 */
-	protected SysConfig createSysConfig(String rootDir) {
-		return createDevSysConfig(rootDir);
-	}
-	/**
-	 * 
-	 */
-	protected SysConfig createProdSysConfig(String rootDir) {
-		return new SysConfig(rootDir); 
-	}
-
-	/**
-	 * 
-	 */
-	protected SysConfig createDevSysConfig(String rootDir) {
-		return new SysConfig(rootDir);
-	}
-
 	/**
 	 * 
 	 */

src/main/java/org/wahlzeit/services/DatabaseConnection.java

@@ -57,6 +57,41 @@ public static synchronized DatabaseConnection ensureDatabaseConnection() throws
 
 		return result;
 	}
+
+	/**
+	 * Wait until a database connection can be established or the max retry counter is reached.
+	 * 
+	 * @param retries amount of retries until fail.
+	 * @param sleepTimeBetweenRetries time to wait until next retry in milliseconds.
+	 * @return true if connection could be established, otherwise return false.
+	 */
+	public static synchronized boolean waitForDatabaseIsReady(final int retries, final int sleepTimeBetweenRetries) {
+		int retryCounter = retries;
+		String dbUrl = SysConfig.getDbConnectionAsString();
+		do {
+			try {
+				DatabaseConnection.ensureDatabaseConnection();
+				SysLog.logSysInfo("[success] Service check for URL " + dbUrl);
+				return true;
+			} catch (final SQLException e) {
+				final String msg = String.format("[%d/%d] Retry service check for URL %s", retryCounter, retries, dbUrl);
+				SysLog.logSysInfo(msg);
+				doSleep(sleepTimeBetweenRetries);
+			}   
+
+			retryCounter--;
+		} while (retryCounter > 0);
+
+		SysLog.logSysError("[failure] Service check for URL  " + dbUrl);
+		return false;
+	}
+
+	private static void doSleep(final int sleepTime) {
+		try {
+			Thread.sleep(sleepTime);
+		} catch (final InterruptedException e) {
+		}
+	}
 
 	/**
 	 * 

src/main/java/org/wahlzeit/services/SysConfig.java

@@ -47,7 +47,7 @@ public class SysConfig extends AbstractConfig {
 	public static SysConfig getInstance() {
 		if (instance == null) {
 			SysLog.logSysInfo("creating generic SysConfig");
-			setInstance(new SysConfig(""));
+			setInstance(new SysConfig());
 		}
 		return instance;
 	}	
@@ -104,13 +104,13 @@ public static synchronized void dropInstance() {
 	 * 
 	 */
 	public SysConfig() {
-		this("");
+		this("", "localhost");
 	}
 
 	/**
 	 *
 	 */
-	public SysConfig(String myRootDir) {
+	public SysConfig(String myRootDir, String dbHostName) {
 		// Root directory
 		rootDir = myRootDir;
 
@@ -126,7 +126,7 @@ public SysConfig(String myRootDir) {
 
 		// Database connection
 		doSetValue(SysConfig.DB_DRIVER, "org.postgresql.Driver");
-		doSetValue(SysConfig.DB_CONNECTION, "jdbc:postgresql://localhost:5432/wahlzeit");
+		doSetValue(SysConfig.DB_CONNECTION, "jdbc:postgresql://" + dbHostName + ":5432/wahlzeit");
 		doSetValue(SysConfig.DB_USER, "wahlzeit");
 		doSetValue(SysConfig.DB_PASSWORD, "wahlzeit");
 	}

src/test/java/org/wahlzeit/testEnvironmentProvider/SysConfigProvider.java

@@ -1,5 +1,7 @@
 package org.wahlzeit.testEnvironmentProvider;
 
+import java.util.Optional;
+
 import org.junit.rules.ExternalResource;
 import org.wahlzeit.services.SysConfig;
 import org.wahlzeit.webparts.WebPartTemplateService;
@@ -10,11 +12,12 @@
  * @review
  */
 public class SysConfigProvider extends ExternalResource {
+	private static final String DB_HOST = Optional.ofNullable(System.getenv("WAHLZEIT_DB_HOST")).orElse("localhost");
 
 	@Override
 	protected void before() throws Throwable {
 		SysConfig.dropInstance();
-		SysConfig sysConfig = new SysConfig("src/main/webapp");
+		SysConfig sysConfig = new SysConfig("src/main/webapp", DB_HOST);
 		SysConfig.setInstance(sysConfig);
 		WebPartTemplateService.getInstance().setTemplatesDir(SysConfig.getTemplatesDir());
 	}