This new base image just comes from me doing a fresh `docker build`
and uploading the result. That gives it fresher versions of our
APT dependencies than the image I built a couple of months ago,
speeding up provision by giving it less to install.
From just my experience attempting this change, I've been impressed
with the very fast turnaround in CircleCI for a change -- from `git
push` to the build starting is usually just a couple of seconds.
It also looks like we get much clearer control over the caching
system, and the setup of the environment via a Docker image of our
choice, which can help avoid most of the several minutes Travis takes
to set up our environment before it actually starts running the tests
themselves.
Plus it supports fine-grained parallelism, e.g. by test file:
https://circleci.com/docs/2.0/parallelism-faster-jobs/
So we can probably get much faster builds by making this switch.
Because the environment is much more transparent and even under
our control, I'm also hopeful for more reliable builds.
Greg Price
Greg Price