trusty:
  base_image: buildpack-deps:trusty-scm
  extra_packages: python-virtualenv postgresql-9.3

xenial:
  base_image: buildpack-deps:xenial-scm
  extra_packages: virtualenv postgresql-9.5

trusty:
  base_image: buildpack-deps:trusty-scm
  extra_packages: python-virtualenv postgresql-9.3

xenial:
  base_image: buildpack-deps:xenial-scm
  extra_packages: virtualenv postgresql-9.5

bionic:
  base_image: buildpack-deps:bionic-scm
  extra_packages: postgresql-10

Add a base image for Ubuntu Bionic.
circleci: Add a base image for Ubuntu Bionic.
