Also pass db-password secret to spring backend

Signed-off-by: Friedrich Greiner <greinerfriedrich@gmail.com>

react-java-mysql/backend/src/main/java/com/company/project/configuration/DockerSecretsProcessor.java

@@ -0,0 +1,30 @@
+package com.company.project.configuration;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.env.EnvironmentPostProcessor;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.io.FileSystemResource;
+import org.springframework.core.io.Resource;
+import org.springframework.util.StreamUtils;
+
+/**
+ * Read property from docker secret file.
+ */
+public class DockerSecretsProcessor implements EnvironmentPostProcessor {
+
+	@Override
+	public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
+		Resource resource = new FileSystemResource("/run/secrets/db-password");
+		if (resource.exists() && System.getProperty("MYSQL_PASSWORD") == null) {
+			try {
+				String dbPassword = StreamUtils.copyToString(resource.getInputStream(), Charset.defaultCharset());
+				System.setProperty("MYSQL_PASSWORD", dbPassword);
+			} catch (IOException e) {
+				throw new RuntimeException(e);
+			}
+		}
+	}
+}

react-java-mysql/backend/src/main/resources/META-INF/spring.factories

@@ -0,0 +1 @@
+org.springframework.boot.env.EnvironmentPostProcessor=com.company.project.configuration.DockerSecretsProcessor

react-java-mysql/docker-compose.yaml

@@ -3,6 +3,8 @@ services:
   backend:
     build: backend
     restart: always
+    secrets:
+      - db-password
     environment:
       MYSQL_HOST: db
     networks: