Allow use of existing IAM role for EC2 instance profile

[bstascavage]

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What

• Enhancement of #107 , due to original developer seemingly abandoning the original PR.
  • Adds service_role_name as another 'override', like instance_role_name is in the original PR.
• Allow the user of the module to specify an existing IAM Role name for the instance profile.
• Allow the user of the module to specify an existing IAM Role name for the service profile.
• This IAM role name will be used to create the instance profile that is assigned to the EC2 instances managed by Elastic Beanstalk.

Why

• Some environments/users do not have the ability to create their own IAM roles/policies, for security reasons. This change allows a user to provide their own IAM role if one already exists.
• Currently the module creates an IAM role and a series of permissions for the role.
• It is not possible to specify what permissions to use
• It is not possible to edit the permissions that are created
• This limitation severely limits the capability of the EC2 instances if they require other permissions to operate.

References

• closes #70
• closes #107

[3h4x]

Thanks for PR @bstascavage. We do have tests in this module, can you take a look at them and extend them to test new functionality?

[mergify[bot]]

This pull request is now in conflict. Could you fix it @bstascavage? 🙏

[florian0410]

Hello @bstascavage and thank you for your PR.

This feature would be a great enhancement to the module, i would be glad to help for reviewing it with Cloudposse team.

Are you still working on this ?

[aknysh]

@bstascavage please resolve the conflicts