Add connection between spring boot server and postgresql database

Signed-off-by: Guillaume Lours <guillaume.lours@docker.com>

samples/spring-postgres/backend/src/main/resources/application.properties

@@ -1 +1,11 @@
+spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
+spring.jpa.hibernate.ddl-auto=none
+spring.jpa.hibernate.show-sql=true
 
+spring.datasource.url=jdbc:postgresql://db:5432/${POSTGRES_DB}
+spring.datasource.username=postgres
+spring.datasource.password=${POSTGRES_PASSWORD:db-wrz2z}
+spring.datasource.initialization-mode=always
+spring.datasource.initialize=true
+spring.datasource.schema=classpath:/schema.sql
+spring.datasource.continue-on-error=true