[FIXED] Read docker env variable inside Spring application.yaml

Issue

I'm setting an environment variable inside my docker-compose.yaml file and want to use that variable's value inside my Spring Boot's application.yaml. I was told that doing something like

app:
  auth:
    tokenSecret: tokensecretvaluehere
    tokenExpirationMsec: 864000000
  oauth2:
    sso:
      url: ${SSO_URL}

(where SSO_URL is defined in my docker-compose.yaml) in my Spring application.yaml. However, this causes an error when I run docker-compose up --build because it can't find that variable (error is like: Could not resolve placeholder SSO_URL in value "${SSO_URL}"). This is an example of what my docker-compose.yaml:

api:
    restart: always
    ports:
      - "8080:8080"
    links:
      - redis
      - db
    environment:
      - SERVER_SERVLET_SESSION_COOKIE_DOMAIN=localhost
      - SSO_URL=myvaluehere

I was asked to not uses the System.getenv functions in Java and instead set the variable like above. From there I would just use the @Value annotation to get it in my Java code as like below:

@Value("${app.oauth2.sso.url}")
private String ssoUrl;

This is more of the application.yaml:

heb:
  togglr:
    jwt:
      secret:
        id: 101
      session:
        seconds: 600
      tokenheader: X-TOGGLR-TOKEN
logging:
  level:
    com:
      heb: debug
    default: debug
  path: logs
server:
  error:
    whitelabel:
      enabled: false
  port: 8080
  servlet:
    context-path: /togglr-api
  use-forward-headers: true
spring:
  application:
    name: togglr_api
  freemarker:
    enabled: false
  groovy:
    template:
      enabled: false
  jmx:
    enabled: false
  main:
    banner-mode: 'off'
  thymeleaf:
    cache: false
  security:
    oauth2:
      client:
        registration:
          github:
            clientId:
            clientSecret:
            redirectUri: 
            scope:
              - user:email
              - read:user
app:
  auth:
    tokenSecret:
    tokenExpirationMsec: 864000000
  oauth2:
    sso:
      url: ${SSO_URL}

Solution

Solution was to not use an underscore character in the variable name.

Answered By - sb9
Answer Checked By - Willingham (JavaFixing Volunteer)