Inconsistent behavior of `--mount=type=cache` when `mode` is not explicitly specified

[jackblackevo]

Description

I've encountered an inconsistent behavior when using --mount=type=cache in Dockerfile. When the mode parameter is not explicitly specified, the cache mount doesn't seem to work correctly, despite the documentation stating that the default mode is 0755. However, when I explicitly use --mount=type=cache,mode=0755, it works normally.

Reproduce

1. Create an npm project
2. Run npm install hello
3. Create a Dockerfile with the following content:

   FROM node:20.16.0-alpine3.20
   
   COPY package.json package-lock.json* ./
   
   RUN --mount=type=cache,target=/root/.npm npm cache verify
   
   RUN --mount=type=cache,target=/root/.npm \
     npm install --cache=/root/.npm --prefer-offline --verbose
   
   RUN --mount=type=cache,target=/root/.npm npm cache verify
   

4. Run docker build --progress=plain --no-cache . twice
5. Observe that the cache doesn't seem to be working correctly

Expected behavior

The cache mount should work correctly with the default mode (0755), as per the documentation.

It should work the same as:

FROM node:20.16.0-alpine3.20

COPY package.json package-lock.json* ./

RUN --mount=type=cache,mode=0755,target=/root/.npm npm cache verify

RUN --mount=type=cache,mode=0755,target=/root/.npm \
  npm install --cache=/root/.npm --prefer-offline --verbose

RUN --mount=type=cache,mode=0755,target=/root/.npm npm cache verify

docker version

Client:
 Version:           27.1.1
 API version:       1.46
 Go version:        go1.21.12
 Git commit:        6312585
 Built:             Tue Jul 23 19:55:52 2024
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Desktop  ()
 Engine:
  Version:          27.1.1
  API version:      1.46 (minimum version 1.24)
  Go version:       go1.21.12
  Git commit:       cc13f95
  Built:            Tue Jul 23 19:57:19 2024
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.7.19
  GitCommit:        2bf793ef6dc9a18e00cb12efb64355c2c9d5eb41
 runc:
  Version:          1.7.19
  GitCommit:        v1.1.13-0-g58aa920
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client:
 Version:    27.1.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.16.1-desktop.1
    Path:     /usr/local/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.29.1-desktop.1
    Path:     /usr/local/lib/docker/cli-plugins/docker-compose
  debug: Get a shell into any image or container (Docker Inc.)
    Version:  0.0.34
    Path:     /usr/local/lib/docker/cli-plugins/docker-debug
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.2
    Path:     /usr/local/lib/docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.25
    Path:     /usr/local/lib/docker/cli-plugins/docker-extension
  feedback: Provide feedback, right in your terminal! (Docker Inc.)
    Version:  v1.0.5
    Path:     /usr/local/lib/docker/cli-plugins/docker-feedback
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.3.0
    Path:     /usr/local/lib/docker/cli-plugins/docker-init
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
    Version:  0.6.0
    Path:     /usr/local/lib/docker/cli-plugins/docker-sbom
  scout: Docker Scout (Docker Inc.)
    Version:  v1.11.0
    Path:     /usr/local/lib/docker/cli-plugins/docker-scout

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 9
 Server Version: 27.1.1
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 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: 2bf793ef6dc9a18e00cb12efb64355c2c9d5eb41
 runc version: v1.1.13-0-g58aa920
 init version: de40ad0
 Security Options:
  seccomp
   Profile: unconfined
 Kernel Version: 5.15.153.1-microsoft-standard-WSL2
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 24
 Total Memory: 31.3GiB
 Name: docker-desktop
 ID: 9ac84166-3dc4-4d9e-b820-a7e13e5c2e6c
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Labels:
  com.docker.desktop.address=unix:///var/run/docker-cli.sock
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No blkio throttle.read_bps_device support
WARNING: No blkio throttle.write_bps_device support
WARNING: No blkio throttle.read_iops_device support
WARNING: No blkio throttle.write_iops_device support
WARNING: daemon is not using the default seccomp profile

Additional Info

No response