I have yet to find a solution to the problem of installing a specific release of MongoDB. I've found several SO posts and other resources, to no avail. The official docs say:
sudo apt-get install -y mongodb-org=3.0.12 mongodb-org-server=3.0.12 mongodb-org-shell=3.0.12 mongodb-org-mongos=3.0.12 mongodb-org-tools=3.0.12
But I get error messages saying those versions are not found. I've tried previous versions as well, but I get the same error output.
