v0.9.0-rc2

Welcome to the 0.9.0-rc2 release of buildx!
This is a pre-release of buildx

Please try out the release binaries and report any issues at
https://github.com/docker/buildx/issues.

Notable changes

• New --print flag can be used to run helper functions supported by the BuildKit frontend performing the build and print their results. In Dockerfile this feature can be used to show the build arguments and secrets that the current build supports with --print=outline and list all available Dockerfile stages with --print=targets. This feature is experimental for gathering early feedback and requires enabling BUILDX_EXPERIMENTAL=1 environment variable. We plan to update/extend this feature in the future without keeping backward compatibility. #1100
• Additional build context configuration is now supported in Compose files via x-bake #1256
• --invoke feature now shows more helpful guidance message for common cases and implements help command #1259
• Bake command now loads .env file automatically when building Compose files for compatibility #1261
• Docker driver can now detect if dockerd instance supports initially disabled Buildkit features like multi-platform images #1260 #1262
• Fix interactive containers started with --invoke remaining active after the build and preventing storage release #1257
• Compose Specification has been updated to 1.4.0 #1251
• Additional validation has been added for checking valid driver configurations #1188
• Fix using duration filter with prune command #1252