How to set up run mode in CQ / WEM

Run modes allow you to tune your CQ instance for a specific purpose; for example author, publish or development. This is done by defining collections of configuration parameters for each run mode. A basic set is applied for all run modes, additional sets are each tuned to the purpose of your specific environment.
All configuration settings are stored in the one repository and activated by setting the Run Mode.
Standard run modes are:

• author
• publish
You can also create environment specific run mode such as,

• author, development
• publish, test
• author, intranet, us
• as required...

There are two mechanisms for setting standard and environment specific run mode for your instance:
• To set up standard run mode Use the naming convention:
cq-<run-mode>-<port-number>
For example, set a standard run mode by naming the jar file cq-author-4502 or cq-publish-4503

• To set up environment specific run mode there are two methods,
1) Through <cq-installation-dir>/crx-quickstart/launchpad/sling.properties
Add the following properties (following example is for author, test, uk):
sling.jcrinstall.folder.name.regexp=.*/(install|config)? 
sling.run.modes=author,test,uk 
In above case config.author.test.uk will get picked up (Or whatever with maximum match)

2) Through <cq-installation-dir>/crx-quickstart/launchpad/sling.properties and system property (In start script):
sling.jcrinstall.folder.name.regexp=.*/(install|config)? (In sling property, this is because there is bug in CQ that by default this regex is set up for author)
-Dsling.run.modes=publish,prod,us (In start script)
In above case config.publish.prod.us will get picked up (Or whatever with maximum match)

Configuration values for the run modes are saved in the repository. You can store all configurations in one repository as the run mode is indicated by a suffix on the folder name; for example:
• config, applicable for all run modes
• config.author, used in author run mode
• config.publish, used in publish run mode
• config.<standard-run-mode>.<environment-specific-mode>, used in the applicable run mode

Following order of precedence are used to set up run mode (From top to bottom, Top being highest)
1) From jar file
2) From Sling property
3) From System property

So in above case jar file name will have precedence over system property.

Note that from CQ5.5 there is no need to set sling property regexp to set up run mode. Setting run mode through system property will be enough to decide standard run mode (As regexp issue is fixed in CQ5.5). Another workaround you can do for run mode to work OOTB in CQ5.4 without regexp is use run mode as config.test.us.author instead of config.author.test.us 

How to check run mode 

https://sling.apache.org/site/sling-settings-orgapacheslingsettings.html

http://wemcode.wemblog.com/check-run-mode

How to read config using API
Method 1
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.service.cm.Configuration;
@SuppressWarnings("UnusedDeclaration")
@Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.STATIC)
private ConfigurationAdmin configAdmin;

protected void activate(ComponentContext ctx) {
Configuration conf = configAdmin.getConfiguration("your configuration pid");
String myProp = (String) conf.getProperties().get("any property in your configuration");
}

Method 2
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.service.cm.Configuration;
import org.osgi.service.cm.ConfigurationAdmin;
public class Activator implements BundleActivator {
private ConfigurationAdmin confAdmin;
public void start(BundleContext context) throws Exception {
this.confAdmin = (ConfigurationAdmin) context.getService(context.getServiceReference(ConfigurationAdmin.class.getName()));
Configuration conf = this.confAdmin.getConfiguration("your configuration pid");
String property = (String) conf.getProperties().get("property");
}
}

Method 3, Using configuration impl
import java.util.Dictionary;
import org.osgi.service.component.ComponentContext;

protected void activate(ComponentContext componentContext) {
Dictionary<?, ?> configuration = componentContext.getProperties();
String value = (String) configuration.get(name);
}

Needless to say that your bundle is registered as component

Method 4, When I don't have access to bundle or component context

private static final String MY_SERVICE_CLASS_NAME = MyService.class.getName();

private MyService getMyService() {
Bundle bundle = org.osgi.framework.FrameworkUtil.getBundle(this.getClass());
BundleContext bundleContext = bundle.getBundleContext();
final ServiceReference ref = getBundleContext().getServiceReference(MY_SERVICE_CLASS_NAME);
if(ref == null) {
String message = "No OSGI Services registered under '" + MY_SERVICE_CLASS_NAME + "'";
log.error(message);
throw new IllegalStateException(message);
}
return (MyService)bundleContext.getService(ref);
}

Thanks Wei Zhang from Adobe for providing this method.

Reference:

http://www.pro-vision.de/adaptto/downloads/2011_lightning_Runmodes_and_Configs_for_Fun_and_Profit.pdf

http://dev.day.com/docs/en/cq/current/deploying/configuring_cq.html#Run Modes

Please note that if no standard mode is specified CQ assumes it is author mode through quickstart.

Special thanks to Carsten Ziegeler from Adobe.