Tuesday, May 5, 2015

Netflix Archaius for property management - Basics

Netflix Archaius provides a neat set of features to load dynamic properties into an application.

This blog post is just a documentation of the extent of Archaius that I have understood, there is much more to it than I have documented here, but this should provide a good start:

Default Behavior

Consider a simple properties file:
stringprop=propvalue
listprop=value1, value2, value3
mapprop=key1=value1, key2=value2
longprop=100

If these entries are placed in a config.properties file in the classpath, then the following test demonstrates how each of these properties can be resolved by Archaius in code:

@Test
public void testBasicStringProps() {
    DynamicStringProperty sampleProp = DynamicPropertyFactory.getInstance().getStringProperty("stringprop", "");
    assertThat(sampleProp.get(), equalTo("propvalue"));
}

@Test
public void testBasicListProps() {
    DynamicStringListProperty listProperty = new DynamicStringListProperty("listprop", Collections.emptyList());
    assertThat(listProperty.get(), contains("value1", "value2", "value3"));
}

@Test
public void testBasicMapProps() {
    DynamicStringMapProperty mapProperty = new DynamicStringMapProperty("mapprop", Collections.emptyMap());
    assertThat(mapProperty.getMap(), allOf(hasEntry("key1", "value1"), hasEntry("key2", "value2")));
}

@Test
public void testBasicLongProperty() {
    DynamicLongProperty longProp = DynamicPropertyFactory.getInstance().getLongProperty("longprop", 1000);
    assertThat(longProp.get(), equalTo(100L));
}

Loading Properties from a non-default file in classpath

So now, how do we handle a case where the content is to be loaded from a file with a different name, say newconfig.properties but still available in the classpath. The following is one way to do that:

@Before
public void setUp() throws Exception{
    ConfigurationManager.loadCascadedPropertiesFromResources("newconfig");
}

With this change the previous test will just work.

Another option is to provide a system property to indicate the name of the properties file to load from the classpath:

System.setProperty("archaius.configurationSource.defaultFileName", "newconfig.properties");

Overriding for environments


Now, how do we override the properties for different application environments - Archaius provides a neat feature where a base property file can be loaded up but then overridden based on the context. More details are here. To demonstrate this consider two files, one containing the defaults and one containing overrides for a "test" environment:

sample.properties
sampleprop=propvalue
@next=sample-${@environment}.properties

sample-test.properties
sampleprop=propvalue-test

See the notation at the end of the default file @next=sample-${@environment}.properties, it is a way to indicate to Archaius that more properties need to be loaded up based on the resolved @environment parameter. This parameter can be injected in a couple of ways and the following test demonstrates this:

@Before
public void setUp() throws Exception{
    ConfigurationManager.getConfigInstance().setProperty("@environment", "test");
    ConfigurationManager.loadCascadedPropertiesFromResources("sample");
}

@Test
public void testBasicStringPropsInTestEnvironment() throws Exception {
    DynamicStringProperty sampleProp = DynamicPropertyFactory.getInstance().getStringProperty("sampleprop", "");
    assertThat(sampleProp.get(), equalTo("propvalue-test"));
}

The base property file itself now has to be loaded in through a call to ConfigurationManager.loadCascadedPropertiesFromResources..

Conclusion

These are essentially the basics of Netflix Archaius, there is much more to it of course which can be gleaned from the wiki on the Archaius github site. If you are interested in exploring the samples shown here a little more, they are available in this github project

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