Add new option admin_environment

- This is environment which is intended to be passed only to the batch
  commands, not to the user servers.  However, it is unknown if any
  spawners support this.  Don't rely on it unless the spawner
  explicitely says it supports it.

Author: rkdarst

README.md

@@ -96,6 +96,10 @@ shell which will execute arbitrary user environment configuration
 access to their own cluster user account.  This is something which we
 are working on.
 
+The `admin_environment` option claims to pass environment only to the
+batch spawners, and not the user servers.  This relies on each spawner
+handling environment correctly, and this is *not* checked so you
+should *not* rely on this yet.
 
 ## Provide different configurations of BatchSpawner
 
@@ -162,6 +166,7 @@ Added (user)
 * Add new option exec_prefix, which defaults to `sudo -E -u {username}`.  This replaces explicit `sudo` in every batch command - changes in local commands may be needed.
 * Add `req_prologue` and `req_epilogue` options to scripts which are inserted before/after the main jupyterhub-singleuser command, which allow for generic setup/cleanup without overriding the entire script.  #96
 * SlurmSpawner: add the `req_reservation` option.  #
+* Add the option `admin_environment` which get passed to the batch submission commands (like for authentication) but *not* to the `--export=keepvars` options.  This *should* mean that it is not passed to the user, but not every spawner is checked, so this should *not* be relied on.
 
 Added (developer)
 

SPAWNERS.md

@@ -22,6 +22,8 @@ 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.
 
+`admin_environment` does work with SlurmSpawner.
+
 Use of `srun` is required to gracefully terminate.
 
 

batchspawner/batchspawner.py

@@ -205,6 +205,23 @@ def parse_job_id(self, output):
     def cmd_formatted_for_batch(self):
         return ' '.join(self.cmd + self.get_args())
 
+    def get_admin_env(self):
+        """Get the environment passed to the batch submit/cancel/etc commands.
+
+        This contains all of the output from self.get_env(), plus any
+        variables defined in self.admin_environment.  In fact, only this
+        command is used to pass to batch commands, and the only use of
+        self.get_env() is producing the list of variables to be
+        --export='ed to.  Everything in get_env *must* also be in here
+        or else it won't be used.
+        """
+        env = self.get_env()
+        if self.admin_environment:
+            for key in self.admin_environment.split(','):
+                if key in os.environ and key not in env:
+                    env[key] = os.environ[key]
+        return env
+
     @gen.coroutine
     def run_command(self, cmd, input=None, env=None):
         proc = Subprocess(cmd, shell=True, env=env, stdin=Subprocess.STREAM, stdout=Subprocess.STREAM,stderr=Subprocess.STREAM)