daemon.json: configuring gc policies inconsistent with how = or == are required

[rrauenza]

I did this pull request,

docker/docs#21596

And I realized that my example wasn't actually working. The error messages out of the docker daemon seem to imply that maybe the code is adding ='s to the config before passing it on. It also seems like I am not allowed to break up these "type" filters into a list.

So this appears to be working:

 "filter": [
            "unused-for=48h","type=source.local,type==exec.cachemount,type==source.git.checkout"
          ],

Note that is type=, type==, type==

# docker buildx inspect
Name:   default
Driver: docker

Nodes:
Name:             default
Endpoint:         default
Status:           running
BuildKit version: v0.16.0
Platforms:        linux/amd64, linux/amd64/v2, linux/amd64/v3, linux/386
Labels:
 org.mobyproject.buildkit.worker.moby.host-gateway-ip: 172.16.0.1
GC Policy rule#0:
 All:           false
 Filters:       type==source.local,type==exec.cachemount,type==source.git.checkout
 Keep Duration: 48h0m0.212245572s
 Keep Bytes:    8GiB

But this doesn't (daemon starts, but gc errors):

 "filter": [
            "unused-for=48h","type=source.local,type=exec.cachemount,type=source.git.checkout"
          ],

Note that is type=, type=, type=

level=error msg="gc error: filters: parse error: [type==source.local,type >|=|< exec.cachemount,type=source.git.checkout]: unsupported operator "=": invalid argument\nfailed to parse prune filters [type==source.local,type=exec.cachemount,type=source.git.checkout]\ngithub.com/moby/buildkit/cache.(*cacheManager).pruneOnce\n\t/root/rpmbuild/BUILD/src/engine/vendor/github.com/moby/buildkit/cache/manager.go:1030\ngithub.com/moby/buildkit/cache.(*cacheManager).Prune\n\t/root/rpmbuild/BUILD/src/engine/vendor/github.com/moby/buildkit/cache/manager.go:1010\ngithub.com/docker/docker/builder/builder-next/worker.(*Worker).Prune\n\t/root/rpmbuild/BUILD/src/engine/builder/builder-next/worker/worker.go:295\ngithub.com/moby/buildkit/control.(*Controller).gc.(*Controller).gc.func2.func3\n\t/root/rpmbuild/BUILD/src/engine/vendor/github.com/moby/buildkit/control/control.go:594\ngolang.org/x/sync/errgroup.(*Group).Go.func1\n\t/root/rpmbuild/BUILD/src/engine/vendor/golang.org/x/sync/errgroup/errgroup.go:78\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1695"

This also doesn't work (daemon won't even start):

            "unused-for=48h","type=source.local","type=exec.cachemount","type=source.git.checkout"

I am guessing that the type=, type=, type= is expected to normally work, and that the internal parser code adds a '=' to the first =, but ignores the later ones in the strings.

[rrauenza]

# docker info
Client: Docker Engine - Community
 Version:    27.3.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.17.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.29.7
    Path:     /usr/libexec/docker/cli-plugins/docker-compose