Cleanup of jenkins init scripts run on EC2 VMs

- Add SSH known_hosts for gerrit instances
- Don't run apt-get update as jenkins doesn't run as root or have
  sudo rights to add/update packages.
- Cleanup and commenting of what each section does

Change-Id: I89571bb988a211b226c0b8568b3c1f8ad7226340
diff --git a/jenkins-scripts/basic_settings.sh b/jenkins-scripts/basic_settings.sh
index bf0eea0..47a3f4c 100755
--- a/jenkins-scripts/basic_settings.sh
+++ b/jenkins-scripts/basic_settings.sh
@@ -9,39 +9,31 @@
 # http://www.eclipse.org/legal/epl-v10.html
 ##############################################################################
 
-case "$(facter operatingsystem)" in
-  Ubuntu)
-    apt-get update
-    ;;
-  *)
-    # Do nothing on other distros for now
-    ;;
-esac
-
+# set hostname
 IPADDR=$(facter ipaddress)
 HOSTNAME=$(facter hostname)
 FQDN=$(facter fqdn)
 
 echo "${IPADDR} ${HOSTNAME} ${FQDN}" >> /etc/hosts
 
-#Increase limits
+# Increase limits
 cat <<EOF > /etc/security/limits.d/jenkins.conf
 jenkins         soft    nofile          16000
 jenkins         hard    nofile          16000
 EOF
 
+# keepalive SSH sessions
 cat <<EOSSH >> /etc/ssh/ssh_config
 Host *
   ServerAliveInterval 60
-
-# we don't want to do SSH host key checking on spin-up systems
-Host 10.30.122.*
-  StrictHostKeyChecking no
-  UserKnownHostsFile /dev/null
 EOSSH
 
+# create host-wide known hosts file
 cat <<EOKNOWN >  /etc/ssh/ssh_known_hosts
 github.com ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq2A7hRGmdnm9tUDbO9IDSwBK6TbQa+PXYPCPy6rbTrTtw7PHkccKrpp0yVhp5HdEIcKr6pLlVDBfOLX9QUsyCOV0wzfjIJNlGEYsdlLJizHhbn2mUjvSAHQqZETYP81eFzLQNnPHt4EVVUh7VfDESU84KezmD5QlWpXLmvU31/yMf+Se8xhHTvKSCZIFImWwoG6mbUoWf9nzpIoaSjB+weqqUUmpaaasXVal72J+UX2B+2RPW3RcT0eOzQgqlJL3RKrTJvdsjE3JEAvGq3lGHSZXy28G3skua2SmVi/w4yCE6gbODqnTWlg7+wC604ydGXA8VJiS5ap43JXiUFFAaQ==
+[gerrit.opencord.org]:29418 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQCceEPwEJ5m5tbiL/AB5mY8DfT9UuXsc0l5N4AMxI89g7Vnyb9XOnxubJo2ZmIwDKI6LM5uRCgfIAKmbNNfqA1CL3e/7XKvQ69rrjnM+5swXAvD4ElYppyyU0V9EufuH2AD7zh0VdzqE25TF4nm6A/2neCqcWI7paa8c2h3YbzvHw==
+[gerrit.onosproject.org]:29418 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDgqAmRpkpZoq8Efz4sslaQYnoNCOlPy7nS/72FkvWP06WbPUsutJznSw4moKTZcxHJADW5eanBHxJ3nI8jo/bXC0qHZfzXVeDCklR/Shq8pY3B7I+WLufq4OKEuYim/ahrAYUvSYyBnnz3fLc+DLLiBhL4BBqpd9ocJd/3HZv4wRAWYmfKMKzjF84u6rehe8ZDUoNICsA/K6Wy1bYQnyJOXVBYdxSkdUc6Er1NDu6W/ijZbcpEt+Y4sYoChxKAtsqcFkjaKFgJbotDGVLnWzZTu08PGtZTE+0UyIozSQvsy/7bGSrA7t0am2IRXz0fFNCq/qOWfkwVbt8hRbEIUk/5
+[gerrit.onosproject.org]:29418 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMBzs9fkmwgIqvYavMlIFz95RzDoSBQxHIeBj2BuDz0HLz2qrW2Q2Rksq4OwsAuSjRto3+9/BgIKv1ONnh21KMM=
+[gerrit.onosproject.org]:29418 ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIKkIOHzFGowb9yL7FcWD73YF/xDUQ23/As/HAP3flf/L
 EOKNOWN
 
-# vim: sw=2 ts=2 sts=2 et :