Merge branch 'spawner_detail' into dev

Author: rkdarst

README.md

@@ -90,7 +90,7 @@ Unless otherwise stated for a specific spawner, assume that spawners
 *do* evaluate shell environment for users and thus the [security
 requriemnts of JupyterHub security for untrusted
 users](https://jupyterhub.readthedocs.io/en/stable/reference/websecurity.html)
-are not fulfilled.
+are not fulfilled.  This is something which we are working on.
 
 
 ## Provide different configurations of BatchSpawner

SPAWNERS.md

@@ -16,9 +16,13 @@ Maintainers:
 
 Maintainers: @rkdarst
 
-This spawner enforces the environment if `srun` is used, which is the
-default.  If you *do* want user environment to be used, set
-`req_srun=''`.
+This spawner enforces the environment if `srun` is used to wrap the
+spawner command, which is the default.  If you *do* want user
+environment to be used, set `req_srun=''`.  However, this is not
+perfect: there is still a bash shell begun as the user which could run
+arbitrary startup, define shell aliases for `srun`, etc.
+
+Use of `srun` is required to gracefully terminate.
 
 
 ## `GridengineSpawner`
@@ -38,12 +42,14 @@ Maintainers:
 
 # Checklist for making spawners
 
-- Does your spawner read shell environment before starting?
+- Does your spawner read shell environment before starting?  (See
+  [Jupyterhub Security](https://jupyterhub.readthedocs.io/en/stable/reference/websecurity.html).
 
 - Does your spawner send SIGTERM to the jupyterhub-singleuser process
   before SIGKILL?  It should, so that the process can terminate
-  gracefully.  If you don't see the script end (e.g. you can add `echo
-  "terminated gracefully"` to the end of your script and see it), you
-  should check.  PR #75 might help here, ask the poster to finalize
-  it.
+  gracefully.  Add `echo "terminated gracefully"` to the end of the
+  batch script - if you see this in your singleuser server output, you
+  know that you DO receive SIGTERM and terminate gracefully.  If your
+  batch system can not automatically send SIGTERM before SIGKILL, PR
+  #75 might help here, ask for it to be finished.