## Description When building volumes for the docker executor, we are validating and building unix parts in the following parts: - [Adding Volumes](https://gitlab.com/gitlab-org/gitlab-runner/blob/d1b7fca6ee7811e023249f9dea1344d351f13fff/executors/docker/executor_docker.go#L486-502) - This will not work right now for windows since we are splitting via `:` - [Checking if host mounted volume](https://gitlab.com/gitlab-org/gitlab-runner/blob/v11.8.0/executors/docker/executor_docker.go#L544-566) - This will not work right now for windows since we are splitting via `:` - [Create Build Volume](https://gitlab.com/gitlab-org/gitlab-runner/blob/v11.8.0/executors/docker/executor_docker.go#L503-532) - We are checking if it's root for Linux but not checking for Windows Path - [addHostVolume](https://gitlab.com/gitlab-org/gitlab-runner/blob/d1b7fca6ee7811e023249f9dea1344d351f13fff/executors/docker/executor_docker.go#L356-361) - We merge the two paths with `:` which causes confusion later since we split via `:` When creating the build volume and user ~~[volumes we assume unix path](https://gitlab.com/gitlab-org/gitlab-runner/blob/master/executors/docker/executor_docker.go#L481-497)~~[volumes we assume unix path](https://gitlab.com/gitlab-org/gitlab-runner/blob/v11.8.0/executors/docker/executor_docker.go#L481-497), to support windows we have to check the runtime ~~of the runner~~ of configured Docker Engine and handle this accordingly. ## Proposal This was already done in https://gitlab.com/gitlab-org/gitlab-runner/merge_requests/706/diffs with a [concrete example](https://gitlab.com/gitlab-org/gitlab-runner/blob/9c114ad7a3f6ad5495bdcfa4c100a07241c4326e/executors/docker/executor_docker.go#L438-463), which uses [`splitWindowsPath`](https://gitlab.com/gitlab-org/gitlab-runner/blob/9c114ad7a3f6ad5495bdcfa4c100a07241c4326e/executors/docker/windows_volume.go) that was copied from docker source code itslef, but since we are [importing github.com/docker/docker](https://gitlab.com/gitlab-org/gitlab-runner/blob/1d141ad4e577616e3d8a640f50a4b106eb069061/Gopkg.toml#L48-51) we can use it [directly ](https://github.com/moby/moby/blob/master/volume/mounts/windows_parser.go). ## Links to related issues and merge requests / references https://gitlab.com/gitlab-org/gitlab-runner/merge_requests/706