dogstatsd.py start is deprecated
https://github.com/DataDog/dd-agent/pull/3004
The above PR added an exit if dogstatsd.py is passed a start command. This causes the dd-agent to not start in the heroku buildpack.
Thanks for opening this issue and fixing the problem so quickly @dreid!
We ran into the same issue and actually spent some time bugging datadog support. We sent them this issue and the PR with the breaking change as a reference.
For others that stumble upon this issue when they realize that their apps silently stopped reporting to datadog, here is one more datapoint:
After you upgrade your buildpack (we had to do so manually since we lock our buildpack to a specific revision of this repo) you have to purge the buildpack cache (as @dreid mentioned in #30). I installed the heroku-repo plugin on my machine and ran heroku repo:purge_cache. The next build of your app should work after that.