I have a spring boot application that I have got working in a docker container and now I am trying to move some hard-coded values out of my application.properties. I know these questions get asked a lot but after reading many questions and answers I haven’t been able to resolve my errors.

My application.properties has this

spring.config.import=optional:file:.env[.properties]
spring.datasource.url=${SPRING_DATASOURCE_URL}
spring.datasource.username=${SPRING_DATASOURCE_USERNAME}
spring.datasource.password=${SPRING_DATASOURCE_PASSWORD}
api.key=${API_KEY}

The springboot part of my docker-compose is like this

version: '3.8'

services:
  spring-boot:
    image: imagename
    ports:
      - "8090:8090"
      - "5005:5005"
    environment:
      SPRING_DATASOURCE_URL: ${SPRING_DATASOURCE_URL}
      SPRING_DATASOURCE_USERNAME: ${SPRING_DATASOURCE_USERNAME}
      SPRING_DATASOURCE_PASSWORD: ${SPRING_DATASOURCE_PASSWORD}
      API_KEY: ${API_KEY}
    depends_on:
      - mysql

And then my .env file in the same directory as my docker-compose

SPRING_DATASOURCE_URL=jdbc:mysql://localhost:3306/db_name
SPRING_DATASOURCE_USERNAME=username
SPRING_DATASOURCE_PASSWORD=password
API_KEY=apikey

When I hardcode the values into the docker-compose the container runs fine. When I run the application locally it runs fine. I had the environment variables as different names and that made no difference.

I am getting a lot of errors but this is at the top

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
2024-07-02 16:01:07 
2024-07-02 16:01:07 The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

I have tried adding in a env_file option but that doesn’t change anything as the env_file option only passes those variables to the containers and not the Docker Compose file.

I would appreciate any help on this as I am quite stuck, thanks!