make cluster-enabled mode a bit more automated

[jim80net]

This PR adds the following functionality when setting cluster_mode_enabled == true:

• Automatically set number of nodes in cluster_size, enabling scale-out with a single parameter change.
• Automatically set the cluster-enabled parameter as an override-able default.

This PR makes the following fixes when setting cluster_mode_enabled == true:

• correct the endpoint keyname to fix a null value error.

[aknysh]

/codefresh run test

[aknysh]

/codefresh run test

[aknysh]

@jim80net

please rebuild README by executing these commands:

make init
make readme/deps
make readme

[jim80net]

Could it be a failing test?

2020-02-06T03:53:36Z |ruby-2.6.3| MacBook-Pro-(4) in ~/workspace/github.com/scribd/terraform-aws-elasticache-redis
±  |cluster_enabled_in_default_parameter_group ✓| → git co 8afc1f80978e146d6bbc728976e37b2702f64621
Note: checking out '8afc1f80978e146d6bbc728976e37b2702f64621'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b <new-branch-name>

HEAD is now at 8afc1f8 chore: terraform fmt

2020-02-06T03:54:42Z |ruby-2.6.3| MacBook-Pro-(4) in ~/workspace/github.com/scribd/terraform-aws-elasticache-redis
±  |detached:cluster_enabled_in_default_parameter_group ✓| → make init
exit 0
Removing existing build-harness
Cloning https://github.com/cloudposse/build-harness.git#master...
Cloning into 'build-harness'...
remote: Enumerating objects: 22, done.
remote: Counting objects: 100% (22/22), done.
remote: Compressing objects: 100% (17/17), done.
remote: Total 1249 (delta 7), reused 10 (delta 5), pack-reused 1227
Receiving objects: 100% (1249/1249), 304.62 KiB | 1.51 MiB/s, done.
Resolving deltas: 100% (662/662), done.

2020-02-06T03:55:02Z |ruby-2.6.3| MacBook-Pro-(4) in ~/workspace/github.com/scribd/terraform-aws-elasticache-redis
±  |detached:cluster_enabled_in_default_parameter_group ✓| → make readme/deps
Installing packages 0.95.0...
Cloning into '/Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/vendor/packages'...
remote: Enumerating objects: 293, done.
remote: Counting objects: 100% (293/293), done.
remote: Compressing objects: 100% (144/144), done.
remote: Total 293 (delta 52), reused 245 (delta 43), pack-reused 0
Receiving objects: 100% (293/293), 52.60 KiB | 681.00 KiB/s, done.
Resolving deltas: 100% (52/52), done.
curl --retry 3 --retry-delay 5 --fail -sSL -o /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/vendor/gomplate https://github.com/hairyhenderson/gomplate/releases/download/v3.1.0/gomplate_darwin-amd64-slim && chmod +x /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/vendor/gomplate

2020-02-06T03:55:24Z |ruby-2.6.3| MacBook-Pro-(4) in ~/workspace/github.com/scribd/terraform-aws-elasticache-redis
±  |detached:cluster_enabled_in_default_parameter_group ✓| → make readme
curl --retry 3 --retry-delay 5 --fail -sSL -o /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/vendor/terraform-docs https://github.com/segmentio/terraform-docs/releases/download/v0.4.5/terraform-docs-v0.4.5-darwin-amd64 && chmod +x /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/vendor/terraform-docs
Generated README.md from /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/templates/README.md.gotmpl using data from /Users/jimp/workspace/github.com/scribd/terraform-aws-elasticache-redis/build-harness/templates/README.yaml

2020-02-06T03:56:02Z |ruby-2.6.3| MacBook-Pro-(4) in ~/workspace/github.com/scribd/terraform-aws-elasticache-redis
±  |detached:cluster_enabled_in_default_parameter_group ✓| → git status --porcelain && echo clean || echo dirty
clean

[maximmi]

/codefresh run test

[maximmi]

thanks @jim80net