When `deploy` is run user_data is sent to AWS.  The user_data defines the type of deployment,
i.e. Demo, es cluster, frontend, etc.  The user_data is compiled in two stages.  The first 
stage creates an Assembled Template.  By default the template is in memory but a `deploy`
argument exists that allows the assembled template to be saved and used later.  The second stage 
adds Run Variables to the Assembled Template.  Then it can be sent as user_data to AWS to create
an instance.

# Standard Templates
Demo/QA Demo                : app-es-pg-template.yml
Cluster Frontend            : app-pg-template.yml
Cluster Elasticsearch       : es-nodes-template.yml

# Non Standard Templates
Instance with remote pg     : app-es-template.yml
Instance with remote pg/es  : app-template.yml

Open one of the templates above to compare with ./template-parts.  Each variable '%(varname)s' 
in the template has a matching file in ./template-parts.  Next is a way to view and save
assembled templates.

We can save Assembled Templates with the --save-configure `deploy` argument.  It will
automaticallly determine which template to used based on input arguments.

$ deploy --save-config-name 20200430

### Output
Created assembeled template
       ./cloud-config/assembled-templates/20200430-app-es-pg.yml
Deploy with
       $ deploy --use-prebuilt-config 20200430-app-es-pg
Diff with on the fly assembly.  Does not deploy
       $ deploy --use-prebuilt-config 20200430-app-es-pg --diff-configs
###

template-parts              : Pieces of the templates
run-scripts                 : Install scripts runcmd_* template parts
configs                     : Configuration files used in run-scripts, like apache, java, es
assembled-templates         : Saved.  These still contains Run Varialbes

create-ami.py               : Create amis from deployed --ami-build in AWS

* Run variables are in /etc/environment file on the instance.  
* They are used in the run-scripts to configure the system and application builds
* /etc/environment is loaded into login/ssh sessions so you can echo them on the instance.
* The file will contain dupicate entries when deploying from an AMI.  Last ones are used.

View them locally with --dry-run along with other info.  Does not deploy
$ deploy --dry-run

Add options like --test, --release-candidate, or --candidate to see the differences in run vars.
Txhe ROLE should change along with other variables like ENCD_INDEX_PRIMARY or ENCD_INDEX_VIS.  The env vars are prefixed with ENCD_ as to not conflict with other env vars.