Eventually we might want to set these thresholds to have better ranges,
but for trying the stack out I say that we shouldn't require an more
than the minimum number of machines.

parameterize availability zones; reformat templ maps

Added defaults to some of the settings to make it more likely that
someone will get a stack up and running on the first try: deployment
key and environment tag.

Parameterized the availability zones instead of hardcoding them to
us-east-1. Each region has it's own notion of what is primary and
what is secondary, etc. because it seems that not all capabilities
work in all AZ's.  Specifically I got this error when trying to
create a VPC in us-west-1.

> Value (us-west-1b) for parameter availabilityZone is invalid. Subnets
> can currently only be created in the following availability zones:
> us-west-1c, us-west-1a.

For us-east-1 "B" and "C" are still the primary and secondary so EdX
shouldn't be affected. But in us-west-1 primary=A and secondary=C.
We'll have to learn over time what works best for other regions.

Reformatted the mapping sections to make them easier to read.  Hope
you don't mind.  Much terser and easier to eyeball.

Terser overall description.  Removed the "you'll be billed!" warning.

Change made in other tempates, doing for this template too. At some
point there was a copy/paste error and the eu-west-1 was used for
us-west-1. See 2cba8413

change module->library, update the example playbook

By default ansible will load libs in library/ which means
you do not need to specify a module path if you are invoking
ansible from the playbooks/ dir.

Added some comments to the rolling example

Bugfixes/jbau/ami and sync hooks

Fixing names

Looks like there was a copy/paste error, the AMI's that were in there
before were the same as Europe.  These new ones work.

Implements simple rolling deploy logic.

Requires the latest ansible to use (you may need to remove and add it again if
you are in a virtualenv)

See `edxapp_rolling_example.yml`

A new module is necessary for ELB information since that is not
available in EC2 metadata (which is what ec2_facts fetches).

ec2_facts grabs the instance ids and other meta information
ec2_elb_facts fetches ELB information
elb_reg.py takes an elb and instance id and will either register or
deregister. (called as pre and post).

`Serial` should be set to the number of instances that you want to
operate on simultaneously, currently set to 1.

Feature/jarv/move vars to role

Adding pre-commit and post-checkout hooks

This keeps vars that are specific to roles with the role, not
very well documented except in the playbook example here:
https://github.com/ansible/ansible/blob/devel/examples/playbooks/roletest.yml

This makes playbooks more concise since you do not have to explicitely
include vars for each roles, var_files will still override any of the
default values in <role>/vars/main.yml

package installation will be managed by config management system, in our...

Jarv/multi instance

* Make git hooks always execute utilities relative to git repository root
* And make them fail if called from outside the git repository
* Make utilities save current directory and return after doing their
  things

Updating default tempalte to point to the multi-instance

* Pre-commit hook lints JSON
* Post-checkout hook causes hooks directory to update with current
  project hooks
* Readme updated so installation section reminds you to install hooks

Jbau/bugfix/apt get update

lms now depends on the nginx role

Jrbl/feature/doc update

* It can be either way (ansible doesn't care) but it should be only one
  way, and the preponderance of existing configuration used .yml.
* Update to README to reflect changed filenames.

* Make it convenient (albeit, mandatory) to set AWS region on the
  command line when calling ansible-playbook for cloudformation

* Wrap to 80 columns
* improved markdown conformance and plaintext readability
* note about setting PYTHONPATH inside squeaky clean virtualenvs
* note about using WikiWords as your cloudformation stack names
* note about how sometimes ansible says 'ok' when cloudformation says
  something broke

fixing yaml syntax for include statement