Bake --load not working in certain context

[devinrsmith]

Contributing guidelines

• I've read the contributing guidelines and wholeheartedly agree

I've found a bug and checked that ...

• ... the documentation does not mention anything about my problem
• ... there are no open or closed issues that are related to my problem

Description

I just noticed that for one of my bake files, --load was not working. Manually using "--set=*.output=type=docker" instead seemed to work. The image does have a tag specified, and the following set of commands illustrates what I see.

$ docker buildx bake -f server-slim-base.hcl --print       
[+] Building 0.0s (1/1) FINISHED                                                                                                                                                                                     
 => [internal] load local bake definitions                                                                                                                                                                      0.0s
 => => reading server-slim-base.hcl 1.74kB / 1.74kB                                                                                                                                                             0.0s
{
  "group": {
    "default": {
      "targets": [
        "server-slim-base"
      ]
    }
  },
  "target": {
    "server-slim-base": {
      "context": "contexts/server-slim-base",
      "dockerfile": "Dockerfile",
      "args": {
        "GRPC_HEALTH_PROBE_VERSION": "0.4.28",
        "OPENJDK_VERSION": "21",
        "UBUNTU_VERSION": "24.04"
      },
      "tags": [
        "deephaven/server-slim-base:latest"
      ]
    }
  }
}

$ docker buildx bake -f server-slim-base.hcl --load 
[+] Building 2.7s (16/16) FINISHED                                                                                                                                              docker-container:interesting_wescoff
 => [internal] load local bake definitions                                                                                                                                                                      0.0s
 ...
 => CACHED [openjdk-bits 1/1] COPY --link --from=openjdk /opt/java/openjdk /opt/java/openjdk                                                                                                                    0.0s
WARNING: No output specified for server-slim-base target(s) with docker-container driver. Build result will only remain in the build cache. To push result image into registry use --push or to load image into docker use --load

$ docker buildx bake -f server-slim-base.hcl "--set=*.output=type=docker"
[+] Building 2.0s (18/18) FINISHED                                                                                                                                              docker-container:interesting_wescoff
 => [internal] load local bake definitions                                                                                                                                                                      0.0s
 ...
 => CACHED [openjdk-bits 1/1] COPY --link --from=openjdk /opt/java/openjdk /opt/java/openjdk                                                                                                                    0.0s
 => exporting to docker image format                                                                                                                                                                            0.4s
 => => exporting layers                                                                                                                                                                                         0.0s
 => => exporting manifest sha256:9b1248f49e831bbb26316db691faeca6edd751b41c42a564a93263484808e1d2                                                                                                               0.0s
 => => exporting config sha256:c4b55cab22e6259841126a48fe19f9c27021251a4341aeae02f2153babc909a5                                                                                                                 0.0s
 => => sending tarball                                                                                                                                                                                          0.4s
 => importing to docker                                                                                                                                                                                         0.0s

Other bake files I have seem to work with --load, so I'm not sure if it's something specific to this file, or some sort of bug in the command.

Expected behaviour

 => exporting to docker image format                                                                                                                                                                            0.4s
 => => exporting layers                                                                                                                                                                                         0.0s
 => => exporting manifest sha256:9b1248f49e831bbb26316db691faeca6edd751b41c42a564a93263484808e1d2                                                                                                               0.0s
 => => exporting config sha256:c4b55cab22e6259841126a48fe19f9c27021251a4341aeae02f2153babc909a5                                                                                                                 0.0s
 => => sending tarball                                                                                                                                                                                          0.4s
 => importing to docker  

Actual behaviour

WARNING: No output specified for server-slim-base target(s) with docker-container driver. Build result will only remain in the build cache. To push result image into registry use --push or to load image into docker use --load

Buildx version

github.com/docker/buildx v0.17.1 257815a

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

Server:
Containers: 14
Running: 3
Paused: 0
Stopped: 11
Images: 1612
Server Version: 27.3.1
Storage Driver: btrfs
Btrfs:
Logging Driver: json-file
Cgroup Driver: systemd
Cgroup Version: 2
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
Swarm: inactive
Runtimes: io.containerd.runc.v2 runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 7f7fdf5fed64eb6a7caf99b3e12efcf9d60e311c
runc version: v1.1.14-0-g2c9f560
init version: de40ad0
Security Options:
seccomp
Profile: builtin
cgroupns
Kernel Version: 6.10.12-200.fc40.x86_64
Operating System: Fedora Linux 40 (Workstation Edition)
OSType: linux
Architecture: x86_64
CPUs: 24
Total Memory: 125.7GiB
Name: felian
ID: GWSW:TIWK:EZ6O:SF4U:ASSR:YG4E:YV6X:I5XQ:ZV4K:SC54:LARV:YMZZ
Docker Root Dir: /var/lib/docker
Debug Mode: false
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false

WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

Builders list

NAME/NODE DRIVER/ENDPOINT STATUS BUILDKIT PLATFORMS
interesting_wescoff* docker-container
_ interesting_wescoff0 _ unix:///var/run/docker.sock running v0.13.1 linux/amd64, linux/amd64/v2, linux/amd64/v3, linux/arm64, linux/riscv64, linux/ppc64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/loong64, linux/arm/v7, linux/arm/v6
default docker
_ default _ default running v0.16.0 linux/amd64, linux/amd64/v2, linux/amd64/v3, linux/arm64, linux/riscv64, linux/ppc64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/loong64, linux/arm/v7, linux/arm/v6

Configuration

The repository is https://github.com/deephaven/deephaven-server-docker, and I'm able to reproduce using docker buildx bake -f server-slim-base.hcl --load.

Build logs

No response

Additional info

No response