[RFC] Clean up of MeshCataloger interface

[draychev]

This GitHub Issue is for the exploration and design of a new cleaner MeshCataloger interface.

• Started: 2021-04-08
• Current Status: Research & Gathering Feedback phase

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Ongoing Changes

These are PRs and issues that are meant to be merged (fixed) and will improve the mesh catalog interface:

• Pull releaseCertificateHandler out of Mesh Catalog into a separate package Pull releaseCertificateHandler out of Mesh Catalog into a separate package #3106
• RFC: Split Proxy Registry from Mesh Catalog interface (removes RegisterProxy, UnregisterProxy, ExpectProxy) RFC: Carve Proxy Registry out of Mesh Catalog interface (removes RegisterProxy, UnregisterProxy, ExpectProxy) #3105
• Removing ListSMIPolicies() and ListMonitoredNamespaces() from MeshCataloger interface Removing ListSMIPolicies() and ListMonitoredNamespaces() from MeshCataloger interface #3109
• catalog: delete interface function ListMonitoredNamespaces() catalog: delete interface function ListMonitoredNamespaces() #3084
• catalog: Remove GetServicesForServiceAccount from MeshCataloger interface catalog: Remove GetServicesForServiceAccount from MeshCataloger interface #3115
• catalog: Remove ListEndpointsForService from MeshCataloger interface catalog: Remove ListEndpointsForService from MeshCataloger interface #3113
• Use ServiceIdentity type in catalog APIs instead of service.K8sServiceAccount Use ServiceIdentity type in catalog APIs instead of service.K8sServiceAccount #2218
• catalog: Rename GetServicesFromEnvoyCertificate to GetServicesForProxy catalog: Rename GetServicesFromEnvoyCertificate to GetServicesForProxy #3117
• Remove GetSMISpec() from MeshCataloger interface Remove GetSMISpec() from MeshCataloger interface #3148
• catalog: Remove GetServicesFromEnvoyCertificate from MeshCataloger interface catalog: Remove GetServicesFromEnvoyCertificate from MeshCataloger interface #3149

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Explorations:

These are incomplete (unmergeable) PRs showing possible refactors and clean-ups:

• [RFC] catalog: Remove ListServiceAccountsForService and add GetServiceAccountsForCert to MeshCataloger interface [RFC] catalog: Remove ListServiceAccountsForService and add GetServiceAccountsForCert to MeshCataloger interface #3112

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Other Related Proposals:

• [RFC] Proposal to move most types used by mesh catalog into pkg/catalog [RFC] Proposal to move most types used by mesh catalog into pkg/catalog #3116

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Potential cleaned-up interface

After all changes (above) are applied we could end up with the following:

type MeshCataloger interface {
	ListInboundTrafficPolicies(service.K8sServiceAccount, []service.MeshService) []*trafficpolicy.InboundTrafficPolicy
	ListOutboundTrafficPolicies(service.K8sServiceAccount) []*trafficpolicy.OutboundTrafficPolicy
	ListAllowedOutboundServicesForIdentity(service.K8sServiceAccount) []service.MeshService
	ListAllowedInboundServiceAccounts(service.K8sServiceAccount) ([]service.K8sServiceAccount, error)
	ListAllowedOutboundServiceAccounts(service.K8sServiceAccount) ([]service.K8sServiceAccount, error)
	ListAllowedEndpointsForService(service.K8sServiceAccount, service.MeshService) ([]endpoint.Endpoint, error)
	GetResolvableServiceEndpoints(service.MeshService) ([]endpoint.Endpoint, error)
	GetIngressPoliciesForService(service.MeshService) ([]*trafficpolicy.InboundTrafficPolicy, error)
	GetTargetPortToProtocolMappingForService(service.MeshService) (map[uint32]string, error)
	GetPortToProtocolMappingForService(service.MeshService) (map[uint32]string, error)
	ListInboundTrafficTargetsWithRoutes(service.K8sServiceAccount) ([]trafficpolicy.TrafficTargetWithRoutes, error)

	ListMeshServiceForServiceAccount
	GetWeightedClustersForUpstream
	GetServiceAccountsForCert 
}

Added

• ListMeshServiceForServiceAccount
• GetWeightedClustersForUpstream
• GetServiceAccountsForCert

Removed

• GetSMISpec() smi.MeshSpec
• ListServiceAccountsForService(service.MeshService) ([]service.K8sServiceAccount, error)
• ListEndpointsForService(service.MeshService) ([]endpoint.Endpoint, error)
• GetServicesFromEnvoyCertificate(certificate.CommonName) ([]service.MeshService, error)
• GetServicesForServiceAccount(service.K8sServiceAccount) ([]service.MeshService, error)
• ListMonitoredNamespaces() []string
• ListSMIPolicies() ([]*split.TrafficSplit, []service.K8sServiceAccount, []*spec.HTTPRouteGroup, []*access.TrafficTarget)
• RegisterProxy(*envoy.Proxy)
• UnregisterProxy(*envoy.Proxy)
• ExpectProxy(certificate.CommonName)