Use Spring profiles and yaml configuration without Spring Boot

That's a refinement you can do to updgrade legacy applications. Using yaml config files combines with Spring profiles is a great way to configure your apps. Let's see how to do that.

Firstly, let's consider that we weill inject something in a java class depending on the runtime  environment.

@Service
public class MyService {

@Value("${service.url}")
private String URL;

}

application.yaml should be like this :

service:
   url: http://alexdp.free.fr/violetumleditor

---
spring:
  profiles: production

service:
   url: http://violet.sourceforge.net

Thus, if I lauch my applicatin without JVM Spring profile params, URL will be http://alexdp.free.fr/violetumleditor. If I launch it with -Dspring.profiles.active=production, URL will be http://violet.sourceforge.net. Great! But this feature is natively supported only for Spring Boot based applications. So, let's active this on legacy apps with this XML spring config file fragment :

<bean id="yamlProperties"

class="org.springframework.beans.factory.config.YamlPropertiesFactoryBean">

<property name="resources">

<list>

<value>classpath:application.yml</value>

</list>

</property>

<property name="documentMatchers">

<bean

class="mypackage.SpringProfileDocumentMatcher" />

</property>

</bean>

<context:property-placeholder properties-ref="yamlProperties" />

Of course, you saw that we wrote our custom SpringProfileDocumentMatcher.

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Properties;
import java.util.Set;

import org.springframework.beans.factory.config.YamlProcessor.DocumentMatcher;
import org.springframework.beans.factory.config.YamlProcessor.MatchStatus;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.Environment;
import org.springframework.util.StringUtils;


/**
 * Allows to use Spring profiles without Spring Boot for legacy Spring based apps
 * 
 * @author Alexandre de Pellegrin
 *
 */
public class SpringProfileDocumentMatcher implements DocumentMatcher, EnvironmentAware {

private static final String[] DEFAULT_PROFILES = new String[] { "default" };

private String[] activeProfiles = new String[0];

public SpringProfileDocumentMatcher() {
}

public SpringProfileDocumentMatcher(String... profiles) {
addActiveProfiles(profiles);
}

public void addActiveProfiles(String... profiles) {
LinkedHashSet set = new LinkedHashSet(
Arrays.asList(this.activeProfiles));
Collections.addAll(set, profiles);
this.activeProfiles = set.toArray(new String[set.size()]);
}

@Override
public MatchStatus matches(Properties properties) {
String[] profiles = this.activeProfiles;
if (profiles.length == 0) {
profiles = DEFAULT_PROFILES;
}
return new ArrayDocumentMatcher("spring.profiles", profiles).matches(properties);
}

@Override
public void setEnvironment(Environment environment) {
if (environment != null) {
       addActiveProfiles(environment.getActiveProfiles());
   }
}


private class ArrayDocumentMatcher implements DocumentMatcher {

private final String key;

private final String[] patterns;

public ArrayDocumentMatcher(final String key, final String... patterns) {
this.key = key;
this.patterns = patterns;

}

@Override
public MatchStatus matches(Properties properties) {
if (!properties.containsKey(this.key)) {
return MatchStatus.ABSTAIN;
}
Set values = StringUtils.commaDelimitedListToSet(properties
.getProperty(this.key));
for (String pattern : this.patterns) {
for (String value : values) {
if (value.matches(pattern)) {
return MatchStatus.FOUND;
}
}
}
return MatchStatus.NOT_FOUND;
}
}
}

That's it!