You could consider storing the various parts of the URL in the dataset that feeds the dashboard itself. And then you concatenate them to make a DashboardURL field that you can then use in the Action Filter.
For instance, one of the dashboards we have has links to different dashboards tied to each metric. We store the ending of the URL with the metric and combine this with the website name in the workbook to create the field.
Does this work? Or are you looking to automatically identify the server you're currently on?
I'm sure that'd be ideal, but at least with the above method you only need to change the other parts once.
But i am looking to automatically identify server name .With above process we need to change the calculation atleast once for each dashboard on server which is equal to changing the dashboard actions URL.