Development Report for May 29, 2017

New feature: Long running session

PR for adding long-running session between daemon and cli that enables advanced features like incremental context send, build credentials from the client, ssh forwarding, etc. is ready for reviews. It is blocking many new features like the token signing, not pulling unnecessary context files, exposing sources outside working directory, etc. Maintainers are encouraged to give this one a review!

Quality: Dependency interface switch

Work continues on making the builder dependency interface more stable.

Merged as part of this effort this week:

@dnephin continues working on the copy/export aspects of the interface.


Some initial proof of concept code for buildkit has been pushed to . It's in a very early exploratory stage. Current development has been about providing concurrent references based access to the snapshot data that is backed by containerd. More info should follow in next weeks, including hopefully opening up an official repo. If you have questions or want to help, stop by the issues section of that repo or the proposal in moby/moby.

Proposals discussed in maintainers meeting

Reminder from last week: New builder proposals were discussed in maintainers meeting. The decision was to give 2 more weeks for anyone to post feedback to IMPORT/EXPORT commands and RUN --mount and accept them for development if nothing significant comes up.

New issue about build secrets has not got much traction. If you want this feature to become a reality please make yourself heard.

Proposals for new Dockerfile features that need design feedback:

Add IMPORT/EXPORT commands to Dockerfile

Add DOCKEROS/DOCKERARCH default ARG to Dockerfile

Add support for RUN --mount

DAG image builder

Option to export the hash of the build context (new)

Allow --cache-from=* (new)

If you are interested in implementing any of them, leave a comment on the specific issues.

Other new builder features currently in code-review:

Fix canceling builder on chunked requests

Fix parser directive refactoring

Warn/deprecate continuing on empty lines in Dockerfile

Fix behavior of absolute paths in .dockerignore