I need to pass an ID as an input parameter to a visual workflow.
I could not find any documentation on how to do it.
Is it possible?
The short answer is Yes, absolutely.
You can pass variables using the standard HTTP URL parameters.
So from the lead page you can have a link to launch a flow and pass the leadID as the following
where vaLeadID is the unique name of the variable in flow.
If you are using a Visualforce Page with a flow embedded in it, you can pass the values using the tag in a VF page, something like this:
<apex:page> <flow:interview name="MyFlow"> <apex:param name="var1" value="Value1"/> </flow:interview> </apex:page>