Spring Boot Docker Image with external environment configuration

application.yml

spring:
    data:
        mongodb:
            host: ${MONGO_HOST}
            port: ${MONGO_PORT}
            database: ${MONGO_DB}

build.gradle

bootRun {
    // Defaults to DEVELOPMENT env file
    File file = file('dev.env')

    println "Loading environment configuration: "
    def envProps = [:]
    if (file.canRead()) {
        def lines = file.readLines()
        for (def line : lines){
            def props = line.split("=")
            println line
            envProps[props[0]] = props[1]
        }
    }

    environment(envProps)
}

dev.env

MONGO_HOST=localhost
MONGO_PORT=27017
MONGO_DB=my_test_db

docker env with spring boot

docker run --env-file=dev.env spring-boot-test-app

docker-compose

spring-boot-test-app:
  build: .
  env_file:
    - dev.env