formalize the notion of an environment configuration

Create the structure and notion of environment configuration
in tripleo-quickstart.  Environmental configuration would be
defined as any configuration that does not change featureset
values or node topology.  This is for the naunces that are
required to run tripleo in different host environments whether
that be rdo-ci, tripleo-ci, ovb in a specific cloud etc.

Change-Id: I4cf2e1cac0325837deeefa889a3699e0db0ec7d8

config/environments/default_libvirt.yml

@@ -0,0 +1 @@
+environment_type: libvirt

doc/source/environment-configuration.rst

@@ -0,0 +1,32 @@
+.. _environment-configuration:
+
+Environment Configuration
+=========================
+
+TripleO-Quickstart has the requirement and capacity to execute in several
+different environments and using different types of systems to bootstrap
+the environments.
+
+Some known examples of different environments are:
+
+  * upstream OpenStack CI
+  * CI CentOS (ci.centos.org)
+  * local libvirt environments
+  * running OVB based deployments in various clouds
+  * Using a CentOS or RHEL qcow2 image without preinstalled OpenStack RPMS.
+
+Anything defined in an environment configuration file should not impact or
+overwrite a variable in a featureset, topology or release configuration file.
+There should be no intersection of variables between the three types of
+configuration.
+
+You will find environment configuration files under $repo/config/environments.
+Some of the environment configuration will be stored in TripleO Quickstart or
+TripleO Quickstart Extras, however sometimes the configuration is specific
+to CI and may only exist in the environment itself.  For example variables
+specific to executing TripleO Quickstart in upstream will live in
+https://github.com/openstack-infra/tripleo-ci/tree/master/toci-quickstart
+
+Example Invocation::
+
+    quickstart.sh -E config/environments/default_libvirt.yml $VIRTHOST

doc/source/index.rst

@@ -10,6 +10,7 @@ Contents:
    configuration
    feature-configuration
    node-configuration
+   environment-configuration
    accessing-libvirt
    accessing-undercloud
    accessing-overcloud

quickstart.sh

@@ -186,6 +186,9 @@ usage () {
     echo "  -N, --nodes <file>"
     echo "                      specify the number of nodes that should be created by"
     echo "                      the provisioner. "
+    echo "  -E, --environment <file>"
+    echo "                      specify additional configuration that is specific to"
+    echo "                      the environment where TripleO-Quickstart is running."
     echo "  -e, --extra-vars <key>=<value>"
     echo "                      additional ansible variables, can be used multiple times"
     echo "  -w, --working-dir <dir>"
@@ -282,6 +285,11 @@ while [ "x$1" != "x" ]; do
             shift
             ;;
 
+        --environment|-E)
+            OPT_ENVIRONMENT=$2
+            shift
+            ;;
+
         --clean|-X)
             OPT_CLEAN=1
             ;;
@@ -383,6 +391,8 @@ fi
 : ${OPT_CONFIG:=$OPT_WORKDIR/config/general_config/minimal.yml}
 # Default Nodes
 : ${OPT_NODES:=$OPT_WORKDIR/config/nodes/1ctlr_1comp.yml}
+# Default Environment
+: ${OPT_ENVIRONMENT:=$OPT_WORKDIR/config/environments/default_libvirt.yml}
 
 # allow the deprecated config files to work
 OLD_CONFIG=""
@@ -481,9 +491,10 @@ else
 fi
 
 ansible-playbook -$VERBOSITY $OPT_WORKDIR/playbooks/$OPT_PLAYBOOK \
-    -e @$OPT_CONFIG \
-    -e @$OPT_NODES \
     -e @$OPT_WORKDIR/config/release/$OPT_RELEASE.yml \
+    -e @$OPT_NODES \
+    -e @$OPT_CONFIG \
+    -e @$OPT_ENVIRONMENT \
     -e local_working_dir=$OPT_WORKDIR \
     -e virthost=$VIRTHOST \
     ${OPT_VARS[@]} \