Docker Builder Enhancements in 20.10.0

- Add DefaultAddressPools to docker info [moby/moby#40714](https://github.com/moby/moby/pull/40714) - Add API support for PidsLimit on services [moby/moby#39882](https://github.com/moby/moby/pull/39882) ### Builder - buildkit,dockerfile: Support for `RUN --mount` options without needing to specify experimental dockerfile `#syntax` directive. [moby/buildkit#1717](https://github.com/moby/buildkit/pull/1717) - dockerfile: `ARG` command now supports defining multiple build args on the same line similarly to `ENV` [moby/buildkit#1692](https://github.com/moby/buildkit/pull/1692) - dockerfile: `--chown` flag in `ADD` now allows parameter expansion [moby/buildkit#1473](https://github.com/moby/buildkit/pull/1473) - buildkit: Fetching authorization tokens has been moved to client-side (if the client supports it). Passwords do not leak into the build daemon anymore and users can see from build output when credentials or tokens are accessed. [moby/buildkit#1660](https://github.com/moby/buildkit/pull/1660) - buildkit: Connection errors while communicating with the registry for push and pull now trigger a retry [moby/buildkit#1791](https://github.com/moby/buildkit/pull/1791) - buildkit: Git source now supports token authentication via build secrets [moby/moby#41234](https://github.com/moby/moby/pull/41234) [docker/cli#2656](https://github.com/docker/cli/pull/2656) [moby/buildkit#1533](https://github.com/moby/buildkit/pull/1533) - buildkit: Building from git source now supports forwarding SSH socket for authentication [moby/buildkit#1782](https://github.com/moby/buildkit/pull/1782) - buildkit: Avoid builds that generate excessive logs to cause a crash or slow down the build. Clipping is performed if needed. [moby/buildkit#1754](https://github.com/moby/buildkit/pull/1754) - buildkit: Change default Seccomp profile to the one provided by Docker [moby/buildkit#1807](https://github.com/moby/buildkit/pull/1807) - buildkit: Support for exposing SSH agent socket on Windows has been improved [moby/buildkit#1695](https://github.com/moby/buildkit/pull/1695) - buildkit: Disable truncating by default when using --progress=plain [moby/buildkit#1435](https://github.com/moby/buildkit/pull/1435) - buildkit: Allow better handling client sessions dropping while it is being shared by multiple builds [moby/buildkit#1551](https://github.com/moby/buildkit/pull/1551) - buildkit: secrets: allow providing secrets with env [moby/moby#41234](https://github.com/moby/moby/pull/41234) [docker/cli#2656](https://github.com/docker/cli/pull/2656) [moby/buildkit#1534](https://github.com/moby/buildkit/pull/1534) - Support `--secret id=foo,env=MY_ENV` as an alternative for storing a secret value to a file. - `--secret id=GIT_AUTH_TOKEN` will load env if it exists and the file does not. - buildkit: Support for mirrors fallbacks, insecure TLS and custom TLS config [moby/moby#40814](https://github.com/moby/moby/pull/40814) - buildkit: remotecache: Only visit each item once when walking results [moby/moby#41234](https://github.com/moby/moby/pull/41234) [moby/buildkit#1577](https://github.com/moby/buildkit/pull/1577) - Improves performance and CPU use on bigger graphs - buildkit: Check remote when local image platform doesn't match [moby/moby#40629](https://github.com/moby/moby/pull/40629) - buildkit: image export: Use correct media type when creating new layer blobs [moby/moby#41234](https://github.com/moby/moby/pull/41234) [moby/buildkit#1541](https://github.com/moby/buildkit/pull/1541) - buildkit: progressui: fix logs time formatting [moby/moby#41234](https://github.com/moby/moby/pull/41234) [docker/cli#2656](https://github.com/docker/cli/pull/2656) [moby/buildkit#1549](https://github.com/moby/buildkit/pull/1549) - buildkit: mitigate containerd issue on parallel push [moby/moby#41234](https://github.com/moby/moby/pull/41234) [moby/buildkit#1548](https://github.com/moby/buildkit/pull/1548) - buildkit: inline cache: fix handling of duplicate blobs [moby/moby#41234](https://github.com/moby/moby/pull/41234) [moby/buildkit#1568](https://github.com/moby/buildkit/pull/1568)

The Docker builder in version 20.10.0 has received numerous enhancements, including support for `RUN --mount` options without requiring the experimental `#syntax` directive and allowing multiple build arguments on the same line. Security improvements include moving authorization token fetching to the client-side and supporting token authentication via build secrets for Git sources. Reliability is improved through retry mechanisms for registry communication errors and mitigation of containerd issues on parallel push. Other updates include improved SSH agent socket support on Windows, better handling of client sessions, and support for mirrors fallbacks and custom TLS configurations.