fixing issue with TMPDIR not being defined

this now reproduces up to the same issue with overlay, which does not work
on my computer. But it might work on someone elses!

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

docker/README.md

@@ -70,7 +70,7 @@ $ salloc -N 1
 $ spindle --no-mpi cat /proc/self/maps
 ```
 
-Notice that ssh works - which spindle should be installed to use.
+Before we run tests, let's get the hosts c1 and c2 added (it will ask you to confirm yes for each)
 
 ```bash
 $ ssh c1
@@ -88,6 +88,13 @@ cd /spindle/testsuite
 ./runTests
 ```
 
+If you need more debug output:
+
+```bash
+# 1, 2, 3
+export SPINDLE_DEBUG=2
+```
+
 Optionally, you can better configure the cluster:
 
 ```bash

docker/docker-entrypoint.sh

@@ -4,6 +4,9 @@ set -e
 # Start ssh in all containers
 systemctl enable sshd
 
+# Ensure TMPDIR envar is defined for all users, spindle needs it
+echo "export TMPDIR=/tmp" >> /etc/profile.d/tmpdir.sh
+
 ssh-keygen -A
 /usr/sbin/sshd -D &