Docker images are way too big

[ghost]

The mithril-client docker image weighs about 1.4GB which is about twice a similar haskell image, and we know Haskell is not very thin :) It's not clear to me why they are so large but we should be able to trim them down.

[jpraynaud]

Hi @abailly, after verification, the images were very big before we merged this PR #525 (where we updated the base image)

Now they are ~120MB for the Client:

REPOSITORY                               TAG            IMAGE ID       CREATED        SIZE
ghcr.io/input-output-hk/mithril-client   latest         d11d65da6a96   24 hours ago   120MB
ghcr.io/input-output-hk/mithril-client   main-46f719c   ffa21583c62c   4 days ago     120MB
ghcr.io/input-output-hk/mithril-client   main-2de1b9b   74ad4167725a   5 days ago     1.33GB
ghcr.io/input-output-hk/mithril-client   main-367fb76   b277cafdd161   13 days ago    1.33GB

Now they are ~245MB for the Signer:

REPOSITORY                               TAG            IMAGE ID       CREATED        SIZE
ghcr.io/input-output-hk/mithril-signer   latest         a03e9e1ee855   24 hours ago   245MB
ghcr.io/input-output-hk/mithril-signer   main-46f719c   bd15a247d132   4 days ago     245MB
ghcr.io/input-output-hk/mithril-signer   main-2de1b9b   910e7a3f77d3   5 days ago     1.46GB
ghcr.io/input-output-hk/mithril-signer   main-367fb76   3fe5563d3e77   13 days ago    1.46GB

Now they are ~265MB for the Aggregator:

REPOSITORY                               TAG            IMAGE ID       CREATED        SIZE
ghcr.io/input-output-hk/mithril-aggregator   latest         94595c047111   24 hours ago   263MB
ghcr.io/input-output-hk/mithril-aggregator   main-46f719c   488d52deed0f   4 days ago     263MB
ghcr.io/input-output-hk/mithril-aggregator   main-2de1b9b   989afc834eca   5 days ago     1.48GB
ghcr.io/input-output-hk/mithril-aggregator   main-367fb76   36b8533ed7b8   13 days ago    1.48GB

We have some room for optimization as the images could be a bit more slim. We plan to address this issue in #318

[abailly]

Thanks a lot 🙏 !