How to read an environment variable in Quarkus

I'm trying to read an environment variable in my Quarkus application using @ConfigProperty, but didn't manage to do that. I thought that just specifying variable name should be enough, but it isn't working:

@ConfigProperty(name = "MY_ENV_VAR")
String envVar;

I've also tried to specify a property in


and read it like

@ConfigProperty(name = "my.var")
String myVar;

but the variable is always null.

Did I miss something? What is the correct way to read an environment variable in Quarkus?
I'm using Quarkus 1.2.0.Final


  • We've found the source of the problem. I was trying to read a field annotated with @ConfigProperty in the constructor, but the properties are being injected only after calling a constructor.

    A working example:

    package org.acme.config;
    import org.eclipse.microprofile.config.inject.ConfigProperty;
    import javax.enterprise.context.ApplicationScoped;
    public class EnvGreetingService {
        private final String varA;
        @ConfigProperty(name = "ENV_VAR_B")
        String varB;
        public EnvGreetingService(@ConfigProperty(name = "ENV_VAR_A") String varA) {
            System.out.println("constructor varA=" + varA);
            System.out.println("constructor varB=" + varB);
            this.varA = varA;
        public void greetWithEnvVar() {
            System.out.println("method varA=" + varA);
            System.out.println("method varB=" + varB);

    Note: it is not required to map environment variables in

    And console output would be:

    constructor varA=a
    constructor varB=null
    method varA=a
    method varB=b

    So, if you want to use application properties or environment variables in the constructor, you should inject it in constructor arguments.