Speed up Gitlab CI reusing docker machine for stages

Question

Gitlab CI pulls docker image every time for every task (stage). This operation wastes much time. I want to optimize if possible.

I see two places to work with:
1. explicitly configure CI stages to reuse the same docker machine.
2. use the docker machine from previous commit when building next commit? (If no changes in configuration file was done).

It shouldn't pull images every time unless they've changed. How have you configured the runner? — Jakub Kania, May 13 '17 at 21:10
That's how you configure the pipelines, not the runner. Are you using the shared runners provided by gitlab.com? — Jakub Kania, May 14 '17 at 17:26
Well, in that case you should set up your own runner. It will keep the images and also your jobs won't have to queue if there's a high load on gitlab's servers. — Jakub Kania, May 14 '17 at 17:32
Thank you. So, the answer is: imposible with default shared runers. Use custom as described on docs. — kyb, May 14 '17 at 17:42
@JakubKania don't you want to post an answer? I'll accept it. — kyb, May 15 '17 at 13:19
Not really, the real answer would require someone to give a definitive proof if that's a feature of share runners or rather of kubernetes the shared runners are using. — Jakub Kania, May 15 '17 at 13:42

rpadovani · Accepted Answer · 2017-05-16T11:59:31.060

This kind of configuration can be specified trough the pull_policy on the runner itself.

As Jakub highlighted in the comments to the question, on shared runners on Gitlab.com the policy is set to always, therefore it will always download a new copy of the image, also if there is the same copy locally.

This due security reasons.

You can have a confirmation of that in the doc.

This pull policy should be used if your Runner is publicly available and configured as a shared Runner in your GitLab instance. It is the only pull policy that can be considered as secure when the Runner will be used with private images.

The security implication is that if the runner checks first a local image, a non authorized user can get a private docker image guessing its name

Speed up Gitlab CI reusing docker machine for stages

1 Answers1