Add Docker configuration.

Add docker-compose and Dockerfile, which spins up a postgres and
vss instance. We override env variables such as vss.jdbc.url,
to point to postgres container.

Dockerfile

@@ -0,0 +1,12 @@
+# Use official Tomcat base image
+FROM tomcat:jre17
+
+# Copy WAR file
+COPY app/build/libs/vss-1.0.war /usr/local/tomcat/webapps/vss.war
+
+ENV vss.jdbc.url="jdbc:postgresql://postgres:5432/postgres"
+ENV vss.jdbc.username=postgres
+ENV vss.jdbc.password=YOU_MUST_CHANGE_THIS_PASSWORD
+
+EXPOSE 8080
+CMD ["catalina.sh", "run"]

docker-compose.yml

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+version: '3.8'
+services:
+  postgres:
+    image: postgres:15
+    environment:
+      POSTGRES_DB: postgres
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: YOU_MUST_CHANGE_THIS_PASSWORD
+    volumes:
+      - postgres-data:/var/lib/postgresql/data
+      - ./app/src/main/java/org/vss/impl/postgres/sql/v0_create_vss_db.sql:/docker-entrypoint-initdb.d/init.sql
+    ports:
+      - "5432:5432"
+    networks:
+      - app-network
+
+  tomcat:
+    build:
+      context: .
+    container_name: tomcat
+    depends_on:
+      - postgres
+    ports:
+      - "8080:8080"
+    networks:
+      - app-network
+
+volumes:
+  postgres-data:
+
+networks:
+  app-network:
+    driver: bridge