Bashrc-style function/alias for running a container within a container

docker-dind.sh

# Typically just stick this in ~/.bashrc
# call it with `docker-dind` or `dind` like you would `docker`
if command -v docker &>/dev/null; then
	dind           () { docker-dind "$@"; }
	dind-deactivate() { unset DOCKER_HOST; }
	dind-activate  () { unset DOCKER_HOST; dind-info; export DOCKER_HOST="$DOCKER_DIND_HOST" DOCKER_DIND_PORTS; }
	dind-info      () {
		local info host_info dind_info tmpfile
		info="{{.Name}}, {{.ServerVersion}}, {{.OperatingSystem}}"
		host_info=$(DOCKER_HOST='' docker info -f "$info")
		tmpfile="/tmp/docker-dind-out.$$"
		docker-dind info -f "$info" > "$tmpfile"; dind_good="$?"
		dind_info=$(<"$tmpfile"); rm -f "$tmpfile"
		if [[ "$host_info" == "$dind_info" ]] || (( dind_good != 0 )); then
			echo "DIND NOT ACTIVE: ${dind_info}"
		else
			echo -ne "DIND ACTIVATED:\n\tHOST: ${host_info}\n\tDIND: ${dind_info}" \
					 "\n\n\tForwarded Ports: ${DOCKER_DIND_PORTS}\n"
		fi
	}
	docker-dind    () {
		local port host id range_s range_e count name
		name=docker_dind; host=localhost; port=4444; range_s=10001; range_e=10101
		if (( $(docker ps -q -f name="${name}" | wc -l) <= 0 )); then
			docker run --privileged \
				-e PORT="$port" -p "${port}":2375 \
				--net host \
				-v "${name}:/var/lib/docker" \
				--name "${name}" \
				-d docker:dind \
				dockerd --host unix:///var/run/docker.sock \
						--host tcp://0.0.0.0:${port} \
				>/dev/null
		fi &&
		until (( $(curl -sio /dev/null -w "%{http_code}" http://${host}:${port}/_ping) == 200 )); do
			sleep .1; (( count > 50 )) \
				&& { echo "Cannot connect to DinD daemon"; return 1; } \
				|| ((++count))
		done
		if [[ $(DOCKER_HOST='' docker inspect ${name} --format="{{ .HostConfig.NetworkMode }}") == "host" ]]; then
			DOCKER_DIND_PORTS="NONE: In host network mode"
		else
			DOCKER_DIND_PORTS="${range_s}${range_e:+-${range_e}}"
		fi
		export DOCKER_DIND_HOST="${host}:${port}" DOCKER_DIND_PORTS
		DOCKER_HOST="$DOCKER_DIND_HOST" docker "$@"
	}
fi