0.21

Highlights:

1. We have renamed the internal builder ch-grow to ch-image to reflect its broader functionality: currently building as well as pulling from a remote repository (and soon pushing to a remote repository). The now-deprecated ch-grow name still works, but we plan to remove it in v0.23. (#895, #924)
2. ch-image unprivileged build workarounds using fakeroot(1) now default to off and must be requested with --force; the option --no-fakeroot has been removed. ch-image will by default print a warning if it thinks --force might fix a build failure. The underlying heuristics of this have also been improved. (#894)

What else is new:

• ch-image pull:
  • now works with registries that use HTTP basic auth (#893, #898)
  • now works with images that use manifest schema version 1 (#814)
  • correctly unpacks layers that replace one type of file with another (#825)
• ch-image build:
  • new option --bind to bind-mount directories during build (#891)
  • COPY: improve symlink and directory handling (#833, #890)
• CI testing now uses GitHub Actions instead of travis-ci.org (#887, #912)
• miscellaneous bug fixes and improvements in:
  • test suite and examples (#860, #875, #879, #925)
  • documentation (#877, #880, #919)
  • build system (#759, #909)

More details: https://github.com/hpc/charliecloud/milestone/27?closed=1
Even more details: v0.20...v0.21