Hi Petri ,
How is your day so far? To obtain the thrift interfaces you need to compile it using the the Thrift compiler Which can be used with Hbase API to obtain these files. Here is an example of Thrift & PHP& Hbase.
thrift –gen php [hbase-root]/src/java/org/apache/hadoop/hbase/thrift/Hbase.thrift
To download the thrift compiler go to this link.
The compiler will generate the PHP interfaces with the thrift lib you are ready to go and package it. Please validate that the thrift server is started first before trying to use the thrift server interfaces.