i’ve updated my example Golang code that authenticates with the Core Reporting API using service account OAuth2 (two-legged) authentication to use the newly updated golang.org/x/oauth2 library.
my previous post & full explanation of service account pre-reqs/setup:
http://code.rickt.org/post/142452087425/how-to-download-google-analytics-data-with-golang
full code:
have fun!
drop me a line or say hello on twitter if any questions.