v1.9.0

This release focuses on bug fixes and developer tooling and UX improvements.

New features and UX changes

• rkt/run: added --set-env-file switch and priorities for environments (#2816). --set-env-file gets an environment variables file path in the format "VAR=VALUE\n...".
• run: add --cap-retain and --cap-remove (#2771).
• store: print more information on rm as non-root (#2805).
• Documentation/vagrant: use rkt binary for getting started (#2808).
• docs: New file in documentation - instruction for new developers in rkt (#2639).
• stage0/trust: change error message if prefix/root flag missing (#2661).

Bug fixes

• rkt/uuid: fix match when uuid is an empty string (#2807).
• rkt/api_service: fix fly pods (#2799).
• api/client_example: fix panic if pod has no apps (#2766). Fixes the concern expressed in #2763 (comment)
• api_service: wait until a pod regs with machined (#2788).

Other changes

• stage1: update coreos image to 1068.0.0 (#2821).
• KVM: Update LKVM patch to mount with mmap mode (#2795).
• stage1: always write /etc/machine-id (#2440). Prepare rkt for systemd-v230 in stage1.
• stage1/prepare-app: always adjust /etc/hostname (#2761).