Read environment variable in SpringBoot

Question

What is the best way to read environment variables in SpringBoot?
In Java I did it using:

String foo = System.getenv(\"         


        

Answer 1

Here are three "placeholder" syntaxes that work for accessing a system environment variable named MY_SECRET:

@Value("${MY_SECRET:aDefaultValue}")
private String s1;

@Value("#{environment.MY_SECRET}")
private String s2;

@Value("${myApp.mySecretIndirect:aDefaultValue}") // via application property
private String s3;

In the third case, the placeholder references an application property that has been initialized from the system environment in a properties file:

myApp.mySecretIndirect=${MY_SECRET:aDefaultValue}

---

For @Value to work, it must be used inside a live @Component (or similar). There are extra gochas if you want this to work during unit testing -- see my answer to Why is my Spring @Autowired field null?