Java – Docker WARNING: Published ports are discarded when using host network mode

I have a Springboot app that I have Dockeriszed.

I have it exposed on port 80801, and can access it as expected.

http://<ipaddress>:8081

Problem

The Springboot app in the docker container needs to connect to a postgres database on the same host (not in a container), but it appears like it does not gave access to the host network.

Connection to localhost:5432 refused

Docker cmd:

docker run -t --rm -d -p 8081:8081 --name nexct-approval-service-container nexct-approval-service-image

So I have read in order to connect to the network, you can use:

--network host 

However, then it stops allowing access to the application itself (port 8081):

WARNING: Published ports are discarded when using host network mode

Question

How can I allow access to the SpringBoot app on port 8081 and allow the Springboot app access to the host network so it can connect to the database?

UPDATE

My database connection is defined in Spring Boot:

application.properties

spring.datasource1.driver-class-name=org.postgresql.Driver
spring.datasource1.jdbc-url=jdbc:postgresql://localhost:5432/pims
spring.datasource1.username=postgres
spring.datasource1.password=

MultipleDBConfig.java

@Configuration
@ComponentScan(basePackages = "com.nexct")
public class MultipleDBConfig {

    @Bean(name = "datasource1")
    @ConfigurationProperties("spring.datasource1")
    @Primary
    public DataSource dataSource1(){
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "datasource2")
    @ConfigurationProperties("spring.datasource2")
    public DataSource dataSource2(){
        return DataSourceBuilder.create().build();
    }
}