render: cannot create Docker network on macOS — Unix socket path percent-encoded as %2F in HTTP URL causes context deadline exceeded #531

What happened?

Running crossplane composition render on macOS with Docker Desktop fails when creating the Docker network for rendering. The Go Docker client incorrectly percent-encodes the Unix socket path in the HTTP URL, producing http://%2Fvar%2Frun%2Fdocker.sock/_ping instead of a valid Unix socket HTTP request — causing a context deadline exceeded timeout.

The error occurs even though Docker is fully functional (docker ps, docker network create all work normally).

Error message

crossplane: error: cannot create Docker network for rendering: cannot create Docker network "crossplane-render-xxxxx": Get "http://%2Fvar%2Frun%2Fdocker.sock/_ping": context deadline exceeded

How to reproduce

1. Install Docker Desktop on macOS (tested with Docker Desktop 4.x, macOS arm64)
2. Install crossplane CLI v2.5.0 via brew
3. Run crossplane composition render <xr.yaml> <composition.yaml>
4. Observe failure at the "cannot create Docker network" step

Workaround

Use socat to bridge the Unix socket to TCP, then set DOCKER_HOST:

socat TCP-LISTEN:2375,bind=127.0.0.1,reuseaddr,fork UNIX-CONNECT:/var/run/docker.sock &
export DOCKER_HOST=tcp://127.0.0.1:2375
crossplane composition render <xr.yaml> <composition.yaml>

Environment

• Crossplane CLI version: v2.5.0
• Platform: darwin/arm64 (macOS)
• Docker Desktop version: 4.x (latest)
• Docker context: desktop-linux (default on macOS)
• Docker socket: /var/run/docker.sock → symlink to ~/.docker/run/docker.sock