need to call set -e on individual build scripts so they also bail out on
failure
create and use a few base docker images because running apt-get upgrade
all the time (if cache is emptied) is slow (and also because it doesn't
lead to a consistent set of binaries if run now vs 2 weeks from now)
fix (and add ut for) crash when getURL fails - httpResp is usually null
in that case
use logger instead of fmt.Printf -- start the main loop immediately
instead of waiting for scrapeInterval