Add support for Keytab

.gitignore

+ktab.priv
+*.keytab

README.md

@@ -10,7 +10,22 @@ You can pass arguments directly on the command line :
 
     docker run -ti --rm -v `pwd`:/work gitlab-registry.cern.ch/industrial-controls/services/dash/worker:latest my-script.py
 
-You can also mount `/build/target` as a persistent volume if you wish to collect the output of your build.
+You can also mount `/opt/spark-nxcals/work` as a persistent volume if you wish to collect the output of your build.
+
+# How to use
+
+
+* Generate a keytab with :
+```
+   cern-get-keytab --user --keytab nxcals.keytab
+```
+* Provide Influxdb connectivity env variables
+* Provide parameters to your extraction script
+* Run :
+```
+docker run -e KPRINCIPAL=$USER -v `pwd`/nxcals.keytab:/auth/private.keytab -v `pwd`/myscript.py:/opt/spark-nxcals/work/script.py etlworker
+``` 
+
 
 # How to release
 

entrypoint.sh

 #!/bin/bash
 source $SPARK_HOME/nxcals-python3-env/bin/activate
  
-export PYTHONPATH=$SPARK_HOME/nxcals-python3-env/lib/python3.6/site-packages:$PYTHONPATH
\ No newline at end of file
+export PYTHONPATH=$SPARK_HOME/nxcals-python3-env/lib/python3.6/site-packages:$PYTHONPATH
+
+if [ -z "$KPRINCIPAL" ]
+then
+    echo "Please provide Kerberos Principal with ENV KPRINCIPAL"
+    exit 1
+else
+    if [ -f /auth/private.keytab ]
+    then
+      echo "Authenticating with provided keytab for principal $KPRINCIPAL"
+      kinit -kt /auth/private.keytab $KPRINCIPAL
+    else
+      echo "Please provide Kerberos keytab at /auth/private.keytab"
+      exit 1
+    fi
+fi
+
+echo "Now running $@"
+exec "$@"
\ No newline at end of file