The jvm_parameters Hydra stage property

There is a special stage-property hidden within Hydra (there since 0.1), that is always available: jvm_parameters.

This is always available and always used, due to the fact that Hydra Core itself reads it, rather than the stage. It's a part of the normal properties-map you set for your stages, but is normally not injected into the stage itself. Actually, from the stage point of view, there's nothing special about this property, so if you for some obscure reason really want to, you can of course have @Parameter String jvm_parameters and have this property be used by both Hydra Core and your stage.

When it starts up your stage, it will use this provided string as part of the command line syntax: java -jar yourstage.jar becomes java <yourparameters> -jar yourstage.jar.

Example usage

When attempting to connect a Hydra stage to an external service over HTTPS, such as an external Solr server using SSL, you might find yourself in trouble if the ROOT CA is untrusted. This can be fairly common in large organizations, that you have an internal ROOT CA that is automatically trusted in standard workplace installations.

1. Use keytool (ships with java) create a .keystore file in which you trust the organization ROOT CA.
2. Store .keystore somewhere hydra can access it: /path/to/keystore/.keystore
3. Set your stage properties to include {solrDeployPath: "https://yoursolrhost/solr/master", jvm_properties : "/path/to/keystore/.keystore", ...}