How to get devcontainerId from the host?

[gc435]

How can I get devcontainerId from the host?

I use devcontainerId to mount a Docker named volume:

"mounts": [
        {
            "source": "my-cache-${devcontainerId}",
            "target": "${containerWorkspaceFolder}/.my-cache",
            "type": "volume"
        }

Over time, a lot of Docker named volumes accumulate in /var/lib/docker/volumes. If I had access to devcontainerId on the host, I could easily know what to keep and what to prune.