How to get value of command line arg into resource class?

[John Chesher]

I'd like to be able to pass a command line argument to my application and be able to access that value from the "resource" class.  I plan to use this to set the hostname:port for which database server I want it to connect to. Any way to do that or "best practices" for doing this?

I've seen this issue:  https://github.com/codahale/dropwizard/issues/40, which relates to overriding certain properties, with the example given of "-Ddw.database.url=jdbc:postgres://yay/whee", but I can not figure out

1) in what file does that property reside (the one being overridden)?

2) how to access it from my "resource" class?

Ideas?  Thanks!

[Christopher Currie]

These command line parameters are part of the Configuration system. The Configuration object tree for your service implements a virtual "path" of command-line values, e.g. if your Configuration object has string property "foo", you can set it using "-Ddw.foo=value", but if it has an object property "foo", and that object has an int property "bar", you can set it using "-Ddw.foo.bar=1".

[John Chesher]

And I should say that I thought about putting a property in the yaml file and adding it to the Configuration class, but the yaml file gets bundled into the deployed jar file.  I guess there are ways to edit the file within the jar, but I was hoping for an approach where I could just override the parameter in the command line, so the contents of the jar file do not have to be touched.

[Tatu Saloranta]

I don't bundle my config files in the jar; there is no requirement to
do that. Why don't you just leave it out? (it does get included if you
store it under Maven source directories)

-+ Tatu +-

[Robert J Antonucci]

These command line parameters are part of the Configuration system... you can set it using "-Ddw.foo=value", 

For those (like me) reading this thread much later, you don't need to use the -Ddw.foo=bar format if you don't want to.  You can just grab strings off the command line like a regular java app, but your command class has to override the configure() method.  So let's say you want to be able to pass in "bar" as a command line argument.

e.g. java -jar myDropWizardApp.jar mycommand bar

Your command class would need to look like this:

public class MyCommand extends Command<MyConfiguration> {

public MyCommand() {

super("mycommand", "Read a string off the command line");

}

public void configure(Subparser argParser) {

argParser.addArgument("foo").nargs("?").help("Optional command line string.");

}

@Override

protected void run(Bootstrap<ViolationsConfiguration> bootstrap,

Namespace namespace, ViolationsConfiguration configuration)

throws Exception {

String fooValue= namespace.getString("foo");

...

}

}

Variations:

If your command is a ConfiguredCommand you need to add

super.configure(argParser);

as the first line of your configure() method or the YML file won't be read.

If you want a non-optional string try

argParser.addArgument("foo").nargs(1).help("Required command line string.");

But that will (for some reason) parse it as a list of one entry.  So to get the value, you need

        String fooValue= (String)namespace.getList("foo").get(0);