Add the ability to run containers in detached mode

docs/deployment/one-off-processes.md

@@ -32,6 +32,13 @@ dokku --rm-container run node-js-app ls -lah
 dokku --rm run node-js-app ls -lah
 ```
 
+Finally, you may wish to run a container in "detached" mode via the `--detach` dokku flag. Note that you may not use the `--rm-container` or `--rm` flags when running containers in detached mode, and attempting to do so will result in the `--detach` flag being ignored.
+
+```shell
+dokku --detach run node-js-app ls -lah
+# returns the ID of the new container
+```
+
 ### Using `run` for cron tasks
 
 You can always use a one-off container to run an application task:

plugins/00_dokku-standard/subcommands/run

@@ -20,8 +20,15 @@ dokku_run_cmd() {
 
   local DOCKER_ARGS=$(: | plugn trigger docker-args-run "$APP" "$IMAGE_TAG")
   [[ "$DOKKU_TRACE" ]] && local DOCKER_ARGS+=" -e TRACE=true "
-  [[ "$DOKKU_RM_CONTAINER" ]] && local DOKKU_RUN_OPTS="--rm"
-  has_tty && local DOKKU_RUN_OPTS+=" -i -t"
+
+  local DOKKU_RUN_OPTS=""
+  if [[ "$DOKKU_RM_CONTAINER" ]]; then
+    DOKKU_RUN_OPTS+=" --rm"
+  elif [[ "$DOKKU_DETACH_CONTAINER" ]]; then
+    DOKKU_RUN_OPTS+=" --detach"
+  fi
+
+  has_tty && DOKKU_RUN_OPTS+=" -i -t"
   is_image_herokuish_based "$IMAGE" && local EXEC_CMD="/exec"
   # shellcheck disable=SC2086
   docker run $DOKKU_GLOBAL_RUN_ARGS $DOKKU_RUN_OPTS $DOCKER_ARGS $IMAGE $EXEC_CMD "$@"

plugins/common/functions

@@ -228,6 +228,9 @@ parse_args() {
       --quiet)
         export DOKKU_QUIET_OUTPUT=1
         ;;
+      --detach)
+        export DOKKU_DETACH_CONTAINER=1
+        ;;
       --trace)
         export DOKKU_TRACE=1
         ;;