Add Private cluster and master ipv4 configuration

[pratikmallya]

Fixes #8

[morgante]

Thanks for this, just a few notes.

[morgante]

We can leave off the note about ip_allocation_policy since this that field isn't exposed to module users.

[morgante]

This LGTM, will merge once tests pass.

[qvallance]

Before merging this, I would recommend refactoring to utilize the new private_cluster_config config block. It depricates the standalone master_ipv4_cidr_block and private_cluster fields and adds new private_cluster_config.master_ipv4_cidr_block, private_cluster_config.enable_private_nodes, and private_cluster_config.enable_private_endpoint fields instead.

[Jberlinsky]

@pratikmallya, thank you very much for your contribution!

Unfortunately, we can't merge this until the integration tests are passing. When I checked out your branch and tried to run it on my local machine, I get numerous errors. Could you please get the output of make test_integration to pass, so we can merge this in?

[morgante]

@qvallance Thanks for the suggestion.

@Jberlinsky Could you file a new PR which takes care of adding this functionality using the new private_cluster_config field? (And making sure tests pass.)

[Jberlinsky]

@morgante Sure, I'd be happy to!

[Jberlinsky]

@morgante Just to confirm, making this change would require moving from the google provider to google-beta. This would force consumers to update their code, as we don't specify a provider explicitly in the module code itself. Is this the direction we wish to move in?

[morgante]

@Jberlinsky I believe we're likely already using some beta fields, we're going to have to address that overall anyways so for now you can ignore the provider split.