identity: Make UnmarshalK8sServiceAccount a method on SDSCert and deprecate as a standalone function

[draychev]

The goal of this GitHub issue is to remove complexity and potential errors.

The function identity.UnmarshalK8sServiceAccount()

osm/pkg/identity/types.go

Line 78 in 6681538

func UnmarshalK8sServiceAccount(svcAccount string) (*K8sServiceAccount, error) {

is used only on SDSCert.Name here:

osm/pkg/envoy/sds/response.go

Line 169 in 6681538

svcAccountInRequest, err := identity.UnmarshalK8sServiceAccount(sdscert.Name)

We may have wanted to use this function for many things in the past, but now it is only parsing SDSCert.Name

I propose we remove UnmarshalK8sServiceAccount() as a standalone function and make it a method on SDSCert.

So instead of UnmarshalK8sServiceAccount(sdsCert) we will have sdsCert.GetK8SServiceAccount() (This obviously assumes a rename from UnmarshalK8sServiceAccount to GetK8SServiceAccount).

---

I propose:

0. To avoid cyclical imports - create a new package - perhaps pkg/envoy/secrets or something similar
1. Move SDSCert{} there:

   osm/pkg/envoy/xdsutil.go

   Lines 22 to 37 in 06e70ae

   	// SDSCertType is a type of a certificate requested by an Envoy proxy via SDS.
   	type SDSCertType string
   	// SDSCert is only used to interface the naming and related functions to Marshal/Unmarshal a resource name,
   	// this avoids having sprintf/parsing logic all over the place
   	type SDSCert struct {
   	// Name is the name of the SDS secret for the certificate
   	Name string
   	// CertType is the certificate type
   	CertType SDSCertType
   	}
   	func (ct SDSCertType) String() string {
   	return string(ct)
   	}

2. Make SDSCert.Name be a new type SDSCertName string
3. Implement SDSCert{}.GetK8SServiceAccount() -- same as UnmarshalK8sServiceAccount(certName)
4. Move (copy code) tests for UnmarshalK8sServiceAccount for SDSCert{}.GetK8SServiceAccount()
5. Remove UnmarshalK8sServiceAccount

---

References

• Similar issue: service: Make UnmarshalMeshServicea a method on SDSCert and deprecate as a standalone function service: Make UnmarshalMeshService a method on SDSCert and deprecate as a standalone function #3221