Add username template

[DesmondH0]

Adding username_template support in vault_database_secret_backend_connection

Question to community:

• Currently only tested with Postgres, and not sure if the username_template should stay in connectionStringResource schema or not, since I don't have db like oracle which is not supporting the username_template to test with.

Community Note

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Relates OR Closes #1030

Release note for CHANGELOG:

Add username_template to vault_database_secret_backend_connection

Output from acceptance testing:

$ make testacc TESTARGS='-run=TestAccXXX'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test $(go list ./... |grep -v 'vendor') -v -run=TestAccXXX -timeout 120m
?   	github.com/hashicorp/terraform-provider-vault	[no test files]
?   	github.com/hashicorp/terraform-provider-vault/cmd/coverage	[no test files]
?   	github.com/hashicorp/terraform-provider-vault/cmd/generate	[no test files]
testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/codegen	0.025s [no tests to run]
?   	github.com/hashicorp/terraform-provider-vault/generated	[no test files]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/datasources/transform/decode	0.033s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/datasources/transform/encode	0.030s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/resources/transform/alphabet	0.034s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/resources/transform/role	0.035s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/resources/transform/template	0.035s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/generated/resources/transform/transformation	0.027s [no tests to run]
?   	github.com/hashicorp/terraform-provider-vault/schema	[no test files]
testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/util	0.037s [no tests to run]
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
	A future release of golang/protobuf will delete this package,
	which has long been excluded from the compatibility promise.

testing: warning: no tests to run
PASS
ok  	github.com/hashicorp/terraform-provider-vault/vault	0.030s [no tests to run]
...

[hashicorp-cla]

All committers have signed the CLA.

[abbasalizaidi]

I want this to be merged! Vault already has support for this.

hashicorp/vault#8063

[angeloskaltsikis]

Hey,
It would be great if we could merge this (it already has 22 👍🏽 ) & release a new version of the provider, as it is currently blocking us from continuing with Vault & MySQL authentication (due to long usernames by default :).

[vinay-gopalan]

Thanks for the PR!

[vinay-gopalan]

Thanks for your response! Sorry for the additional changes, but I think this might be a better way to go when I think more about it

[vinay-gopalan]

Thanks for making the changes!