spring property substitution for test and production

I ran into this for property substitution in spring

<context:property-placeholder location="esb-project-config.properties"/>

but unfortunately, we don't want this in the xml file as we want to re-use the file in our tests but swap in the test.properties file for test. ie. we want to test all the production bindings but with properties that are suitable for test like localhost for instance. How can we load the ApplicationContext but with different properties files?

thanks, Dean

Solution 1:

several approaches:

1. 'Order' Property

in src/main/resources/your-conf.xml

<context:property-placeholder 
         location="classpath:esb-project-config.properties"
         order="1"/>

in src/test/resources/your-test-config.xml

<context:property-placeholder 
         location="classpath:esb-project-config.properties"
         order="0"/>

If you running your test with src/test/resources as a test classpath, the above will ensure to override src/main/resources/esb-project-config.properties with the src/test/resources/esb-project-config.properties.

This will override the whole property-placeholder though, so you would have to provide all the properties needed in your application in for this test property-placeholder. e.g.

<context:property-placeholder 
         location="classpath:esb-project-config.properties,
                   classpath:some-other-props-if-needed.properties"
         order="0"/>

2. PropertyOverrideConfigurer

 <context:property-override 
          location="classpath:esb-project-config.test.properties"/>

to override certain individual properties. Some examples here

3. System Variables

You can use a prefix to control environment specific properties, this can be done by using system variables:

 <context:property-placeholder 
          location="${ENV_SYSTEM:dev}/esb-project-config.properties"/>

In this case it will always look under:

 <context:property-placeholder 
          location="dev/esb-project-config.properties"/>

by default, unless a ENV_SYSTEM system variable is set. If it is set to qa, for example, it will automatically look under:

 <context:property-placeholder 
          location="qa/esb-project-config.properties"/>

4. Spring Profiles

Another approach is to make beans profile specific. For example:

<beans profile="dev">
  <context:property-placeholder 
           location="esb-project-config.dev.properties"/>
</beans>

<beans profile="qa">
  <context:property-placeholder 
           location="esb-project-config.qa.properties"/>
</beans>

The appropriate esb-project-config will loaded depending on a profile set. For example this will load esb-project-config.dev.properties:

GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
ctx.getEnvironment().setActiveProfiles( "dev" );
ctx.load( "classpath:/org/boom/bang/config/xml/*-config.xml" );
ctx.refresh();

• NOTE: "System Variables" and "System Profiles" approaches are usually used to switch between different environments rather than just "dev <==> test" in dev mode, but still are useful capabilities to be aware of.

Solution 2:

Put the property-placeholder configuration in an extra spring xml configuration file.

For example:

• applicationContext.xml -- for the normal configration without any property-placeholder configuration
• applicationContext-config.xml -- contains only a property-placeholder that load the production config file.
• testApplicationContext.xml. This file includes the applicationContext.xml and uses a property-placeholder with an other properties file.

In a Web App you could load all production spring context files with this pattern applicationContext*.xml.

For the tests you need only to load testApplicationContext.xml this will include the normal config, but with other properties.

Solution 3:

• On the context tag you can indicate that if a properties file does not exist it does not need to fail.
• Property files are loaded in the order that they are declared. (This might also be a property to declare on the tag. Not sure)
• If a property is declared multiple times, the last loaded value is used.

We use these three features as follows:

We declare two property files:

classpath:esb-project-config.properties,
classpath:esb-project-config-override.properties

The first property file contains sensible defaults and development configuration. This file is part of your application.

The second property file is a file that is available on the test classpath or even the production classpath of the application server. This file is external of the application That way we can override properties for each environment and have just one version of our application.

So here is the example of the properties we use:

    <context:property-placeholder 
       ignore-resource-not-found="true" ignore-unresolvable="true" 
       location="classpath:esb-project-config.properties,classpath:esb-project-config-override.properties" />