chore: make contribute/start_docker work on Fedora

The docker-podman wrapper created volume mounts are owned by the root
user inside the container, and the doom user wouldn't have write access.
Need to specify --user-ns=keep-id flag to map $UID from the host to $UID
from the container without using subuids: that way user inside container
can modify.

SELinux is on by default on Fedora36, thus volume mounts need to specify
the 'Z' flag to relabel the directory being mounted.

podman needs '--userns=keep-id' for permissions of mounted volumes to
work inside the container.
However docker doesn't recognize that flag (and doesn't need it, since
it is running as root).

Detect which of `docker` or `podman` is installed, and if it is podman
add the extra flag. We need to check for podman first, because 'docker'
might just be a wrapper that calls podman.

Signed-off-by: Edwin Török <edwin@etorok.net>

tools/start_docker.sh

@@ -1,10 +1,16 @@
 #!/usr/bin/env bash
-
-if ! docker info > /dev/null 2>&1; then
+DOCKER=$(command -v podman docker | head -n 1)
+if ! "${DOCKER}" info > /dev/null 2>&1; then
   echo "This script uses docker, and it isn't running - please start docker and try again!"
   exit 1
 fi
 
+if [ $(basename "${DOCKER}") = "podman" ]; then
+	DOCKER_RUN_FLAGS="--userns=keep-id"
+else
+    DOCKER_RUN_FLAGS=
+fi
+
 ############################################################
 # Help                                                     #
 ############################################################
@@ -40,6 +46,7 @@ while getopts "b:h" option; do
       exit;;
   esac
 done
+shift $((OPTIND-1))
 
 cd "$SCRIPT_DIR" || exit
 
@@ -87,30 +94,30 @@ echo ""
 
 echo "2. Setting up docker environment"
 # Ensure docker image exists
-if [[ ! "$(docker images -q doom-nvim-contrib)" ]]; then
+if [[ ! "$("${DOCKER}" images -q doom-nvim-contrib)" ]]; then
   echo " - Docker image does not exist.  Building docker image..."
-  docker build -t doom-nvim-contrib .
+  "${DOCKER}" build -t doom-nvim-contrib .
 fi
 
-if [ "$(docker ps -aq -f status=exited -f name=doom-nvim-contrib-container)" ]; then
+if [ "$("${DOCKER}" ps -aq -f status=exited -f name=doom-nvim-contrib-container)" ]; then
   echo " - Cleaning up old container..."
   # cleanup
-  docker rm doom-nvim-contrib-container >> /dev/null
+  "${DOCKER}" rm doom-nvim-contrib-container >> /dev/null
 fi
 
 # Create docker container if haven't already
 echo " - Success! Running docker container doom-nvim-contrib-container..."
 mkdir -p "${SCRIPT_DIR}/local-share-nvim" "${SCRIPT_DIR}/workspace"
 echo ""
-docker run \
+${DOCKER} run \
+  ${DOCKER_RUN_FLAGS} \
   -it \
   -e UID="1000" \
   -e GID="1000" \
-  -v "$SCRIPT_DIR"/doom-nvim-contrib:/home/doom/.config/nvim \
-  -v "$SCRIPT_DIR"/local-share-nvim:/home/doom/.local/share/nvim \
-  -v "$SCRIPT_DIR"/workspace:/home/doom/workspace \
+  -v "$SCRIPT_DIR"/doom-nvim-contrib:/home/doom/.config/nvim:Z \
+  -v "$SCRIPT_DIR"/local-share-nvim:/home/doom/.local/share/nvim:Z \
+  -v "$SCRIPT_DIR"/workspace:/home/doom/workspace:Z \
   --name doom-nvim-contrib-container \
   --user doom \
-  doom-nvim-contrib
-
-
+  "$@" \
+  doom-nvim-contrib \