How about a bit of the old component action?

ApiUrl.component

<apex:component>{!$Api.Partner_Server_URL_340}</apex:component>

Execute anonymous

PageReference pr = new PageReference('/apexcomponent/apiurl');
pr.getContent().toString();

gives you:

https://bigass--c.eu2.visual.force.com/services/Soap/u/34.0/00D...

How about a bit of the old component action?

ApiUrl.component

<apex:component>{!$Api.Partner_Server_URL_340}</apex:component>

Execute anonymous

PageReference pr = new PageReference('/apexcomponent/apiurl');
pr.getContent().toString();

gives you:

https://mydomain--c.eu2.visual.force.com/services/Soap/u/34.0/00D...

How about a bit of the old component action?

ApiUrl.component

<apex:component>{!$Api.Partner_Server_URL_340}</apex:component>

Execute anonymous

PageReference pr = new PageReference('/apexcomponent/apiurl');
pr.getContent().toString(); //https://bigass--c.eu2.visual.force.com/...

How about a bit of the old component action?

ApiUrl.component

<apex:component>{!$Api.Partner_Server_URL_340}</apex:component>

Execute anonymous

PageReference pr = new PageReference('/apexcomponent/apiurl');
pr.getContent().toString();

gives you:

https://bigass--c.eu2.visual.force.com/services/Soap/u/34.0/00D...