Can the Spring active profiles be set through a property file?

Question

I want to be able to read the active profiles from a property file so that different environments (dev,prod etc) can be configured with different profiles in a Spring MVC based web application. I know that the active profiles can be set through JVM params or system properties. But I would like to do it through a property file instead. The point is that I dont know the active profile statically and instead want to read it from a properties file. It looks like this is not possible. For eg., if I had 'spring.profiles.active=dev' in application.properties, and allow it to be overridden in override.properties like so:

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="ignoreResourceNotFound" value="true" />
    <property name="locations">
        <list>
            <value>classpath:/application.properties</value>
            <value>file:/overrides.properties</value>
        </list>
    </property>
</bean> 

the profile is not being picked up in the environment. I guess this is because the active profiles are being checked before bean initialization, and therefore do not honor the property being set in a properties file. The only other option I see is to implement an ApplicationContextInitializer that will load those property files in order of priority(override.properties first if it exists, else application.properties) and set the value in context.getEnvironment(). Is there a better way to do it from properties files?

Answer 1

One solution to do it is to read necessary property file with specified profile "manually" - without spring - and set profile at context initialization:

1) Write simple properties loader:

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.Properties;

public class PropertiesLoader
{
    private static Properties props;

    public static String getActiveProfile()
    {
        if (props == null)
        {
            props = initProperties();
        }
        return props.getProperty("profile");
    }

    private static Properties initProperties()
    {
        String propertiesFile = "app.properties";
        try (Reader in = new FileReader(propertiesFile))
        {
            props = new Properties();
            props.load(in);
        }
        catch (IOException e)
        {
            System.out.println("Error while reading properties file: " + e.getMessage());
            return null;
        }
        return props;
    }
}

2) Read profile from properties file and set it during Spring container initialization (example with Java-based configuration):

public static void main(String[] args)
{
    AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
    ctx.getEnvironment().setActiveProfiles(PropertiesLoader.getActiveProfile());
    ctx.register(AppConfig.class);
    ctx.refresh();

    // you application is running ...

    ctx.close();
}