How to measure Docker build steps duration?

Question

Is it possible to configure Docker to output timing for the build of a Dockerfile?

We run a medium sized development team and would like to collect statistics on the

Answer 1

I was wondering that too. The only solution I came up with for individual steps is to put date +'%F %T' to the end of each step.

RUN set -x && apt-get update && date +'%F %T'
RUN apt-get install -y vim && date +'Time: %F %T'

Output:

Get:1 http://security.debian.org stretch/updates InRelease [63.0 kB]
...
Time: 2018-03-08 00:42:41

In Bash, you could use echo $SECONDS which gives time since the Bash session start; or time ( ... ) (a subshell), but the Docker build environment runs in sh, not bash.