Add read-only configuration

[codihuston]

• When read-only mode is enabled via rails config, controller endpoints that are explicitly enrolled into a read_safe list return a HTTP 405 Method Not Allowed when invoked, also throwing Conjur error code: CONJ00153E
• Implemented using module prepending

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Implemented Changes

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Connected Issue/Story

Resolves #[relevant GitHub issue(s), e.g. 76]

CyberArk internal issue ID: [insert issue ID]

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[codihuston]

Sample output with Rails.configuration.read_only_api=true

root@86de487fed92:/# conjur policy load root /src/conjur-server/dev/policies/example.yml
{"error":{"code":"method_not_allowed","message":"CONJ00153E This action is not permitted when the server is in read-only mode"}}
error: 405 Method Not Allowed
root@86de487fed92:/# conjur variable values add test-variable test-value
{"error":{"code":"method_not_allowed","message":"CONJ00153E This action is not permitted when the server is in read-only mode"}}
error: 405 Method Not Allowed
root@86de487fed92:/# conjur variable value test-variable
test-value

Sample output with Rails.configuration.read_only_api=false

root@86de487fed92:/# conjur policy load root /src/conjur-server/dev/policies/example.yml
Loaded policy 'root'
{
  "created_roles": {
  },
  "version": 2
}
root@86de487fed92:/# conjur variable values add test-variable test-value
Value added

root@86de487fed92:/# conjur variable value test-variable
test-value

[qlty-cloud-legacy[bot]]

Code Climate has analyzed commit 380bb0a3 and detected 9 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	2
Style	7

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 87.4% (-0.7% change).

View more on Code Climate.