[terraform] add init options -reconfigure and -migrate-state

[wasfree]

As mentioned in #839 it's may a good idea to have terraform init options -reconfigure and -migrate-state configurable.

This PR will add:

• Additional terraform.options Reconfigure and MigrateState
• MigrateState does also enable -force-copy to suppress the prompt for confirmation (similar to -auto-approve)
• Tests for both options TestInitReconfigureBackend and TestInitBackendMigration
• Options directly appended in InitE func due to the fact this options only used by terraform init and do not require any parameters which would require specific formatting

Reference to terraform documentation:
https://www.terraform.io/docs/cli/commands/init.html#backend-initialization

[brikis98]

Thanks for the PR! Code changes LGTM except for some tiny NITs. Once those are resolved, I can kick off tests.

[brikis98]

LGTM, thank you! I'll kick off tests now.

[brikis98]

Precommit check failed:

goimports................................................................Failed
- hook id: goimports
- files were modified by this hook

modules/terraform/init_test.go

Please run goimports!

[wasfree]

Precommit check failed:

goimports................................................................Failed
- hook id: goimports
- files were modified by this hook

modules/terraform/init_test.go

Please run goimports!

Sorry, missed that step in contribution guidelines. Please run tests again.

[brikis98]

LGTM, I'll kick off tests again!

[brikis98]

Looks like there were some relevant test failures:

    init_test.go:109: 
        	Error Trace:	init_test.go:109
        	Error:      	An error is expected but got nil.
        	Test:       	TestInitReconfigureBackend
        	Messages:   	Backend initialization with changed configuration should fail without -reconfigure option

And:

    init_test.go:139: 
        	Error Trace:	init_test.go:139
        	Error:      	An error is expected but got nil.
        	Test:       	TestInitBackendMigration
        	Messages:   	Backend initialization with changed configuration should fail without -migrate-state option

[wasfree]

Looks like there were some relevant test failures:

    init_test.go:109: 
        	Error Trace:	init_test.go:109
        	Error:      	An error is expected but got nil.
        	Test:       	TestInitReconfigureBackend
        	Messages:   	Backend initialization with changed configuration should fail without -reconfigure option

And:

    init_test.go:139: 
        	Error Trace:	init_test.go:139
        	Error:      	An error is expected but got nil.
        	Test:       	TestInitBackendMigration
        	Messages:   	Backend initialization with changed configuration should fail without -migrate-state option

This is related to terraform version used for the test, in version v0.15.0 backend re-initialization was accepted without -migrate-state or -reconfigure. In the meantime the version was updated to v0.15.5 with new behavior e4f4b36 . Rebase done, test should use now v0.15.5.

[bada09089]

Hey @yorinasub17, could you please also review this PR.

[brikis98]

Sorry for the delay. We are doing a virtual company offsite this week, so it's been quite busy. Updates LGTM, I'll re-run the tests now.

[brikis98]

There were some intermittent test failures, but I think they were unrelated to this PR, so I'm going to merge. Thanks!

[brikis98]

https://github.com/gruntwork-io/terratest/releases/tag/v0.36.3