Allow ssh-agent communication when running under systemd

Description

When running a process under systemd, only some env variables are passed into the process, such as $HOME, $SHELL, $USER - that's the default systemd behavior.

Docker-desktop now, is, according to documentation, only passing the ssh-agent to containers if the SSH_AUTH_SOCK is available. Because of the filtered environment, this doesn't work when running via systemd (ie. via systemctl --user start docker-desktop).

Please change the docker-desktop service unit to allow this env variable to be passed to docker-desktop. Example:

[Service]
PassEnvironment=SSH_AUTH_SOCK

Thank you!

Reproduce

run docker desktop via systemctl --user start docker-desktop
run a container with the following volume mounted: -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock
socket wont be available inside the container.

Expected behavior

Socket of ssh-agent running on host should've been passed to the container.

docker version

Client: Docker Engine - Community
 Cloud integration: v1.0.35+desktop.13
 Version:           26.1.4
 API version:       1.45
 Go version:        go1.21.11
 Git commit:        5650f9b
 Built:             Wed Jun  5 11:29:22 2024
 OS/Arch:           linux/amd64
 Context:           desktop-linux

Server: Docker Desktop 4.30.0 (149282)
 Engine:
  Version:          26.1.1
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.21.9
  Git commit:       ac2de55
  Built:            Tue Apr 30 11:48:28 2024
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.31
  GitCommit:        e377cd56a71523140ca6ae87e30244719194a521
 runc:
  Version:          1.1.12
  GitCommit:        v1.1.12-0-g51d5e94
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client: Docker Engine - Community
 Version:    26.1.4
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.14.0-desktop.1
    Path:     /usr/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.27.0-desktop.2
    Path:     /usr/lib/docker/cli-plugins/docker-compose
  debug: Get a shell into any image or container (Docker Inc.)
    Version:  0.0.29
    Path:     /usr/lib/docker/cli-plugins/docker-debug
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.2
    Path:     /usr/lib/docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.23
    Path:     /usr/lib/docker/cli-plugins/docker-extension
  feedback: Provide feedback, right in your terminal! (Docker Inc.)
    Version:  v1.0.4
    Path:     /usr/lib/docker/cli-plugins/docker-feedback
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.1.0
    Path:     /usr/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/lib/docker/cli-plugins/docker-sbom
  scout: Docker Scout (Docker Inc.)
    Version:  v1.8.0
    Path:     /usr/lib/docker/cli-plugins/docker-scout

Server:
 Containers: 21
  Running: 0
  Paused: 0
  Stopped: 21
 Images: 35
 Server Version: 26.1.1
 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: 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: e377cd56a71523140ca6ae87e30244719194a521
 runc version: v1.1.12-0-g51d5e94
 init version: de40ad0
 Security Options:
  seccomp
   Profile: unconfined
  cgroupns
 Kernel Version: 6.6.26-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 7.755GiB
 Name: docker-desktop
 ID: 4c7632dc-c405-40aa-a23f-a15de3eea131
 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=....
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: daemon is not using the default seccomp profile

Diagnostics ID

CE8AFCC7-C832-486B-B16B-D2D5A224E204/20240607150826

Additional Info

No response

docker / desktop-linux