feat: Rework domain-manager standard

Life shows that not all CSPs are capable to adopt the domain manager
requirement due to certain architecture decisions or security requirement.
Suggest a rework that splits requirements into mandatory and recommended.

Signed-off-by: Artem Goncharov <[email protected]>

Standards/scs-0302-v2-domain-manager-role.md

@@ -0,0 +1,143 @@
+---
+title: Domain Manager adoption notes
+type: Standard
+track: IAM
+status: Draft
+replaces: scs-0302-v1-domain-manager-role.md
+---
+
+## Introduction
+
+After the domain manager persona has been implemented certain issues in the
+standard adoption and verification started being raised by CSPs:
+
+- Not every CSP is using domains to separate customers.
+
+- CSP may rely on the Identity federation in which case it is impossible or is
+prohibited to manage identities on OpenStack side (OpenStack is a service
+provider and not an identity provider).
+
+- CSP may customize authorization policies in a different way so that domain
+manager can not be implemented by simply reusing the upstream implementation.
+
+As such simple enforcement of the Domain Manager persona can not be achieved.
+
+This standard clarifies base standard and splits requirements into recommended
+and mandatory to provide better granularity while still giving guidance with
+the goal to provide a smooth user experience for the end users.
+
+Requiring customer to use CSP specific APIs to manage identity data is
+contradicting with the idea of certification as such. It hinders customers from
+having a smooth user experience across different cloud providers forcing them
+to adapt their management strategies on such clouds. Moreover it represent a
+lock-in what is contradicting with the idea of SovereignCloudStack.
+
+### Mandatory capabilities
+
+#### Assign roles to users/group on projects/domain
+
+One of the main initial concerns of the Domain Manager was the ability of the
+customer to manage user permissions in a self-service manner. OpenStack
+Keystone provides an easy possibility to smoothly integrate role assignments
+with arbitrary external systems in a transparent way (a role assignment backend
+plugin can be provided to persist assignments in any external system). As such
+this capability MUST be supported by the CSP using OpenStack APIs or role
+assignments.
+
+#### Project creation
+
+Another important requirement was to provide self-service capability for
+customers to create projects as desired without requesting CSP support. This
+capability MUST be available using native cloud APIs.
+
+#### Project editing
+
+Customer must be able to activate or deactivate project access without
+requesting CSP support. This capability provides possibility to temporarily
+disable users to authorize into certain project by modifying`enabled` property
+of the project. Further control of the project name, description, options and
+tags MUST be provided to the customer using native Keystone API.
+
+:::info
+
+Project deletion using Keystone API is not mandatory since CSP may have certain
+expectations on the resources cleanup. This requirement is described in detail
+in a dedicated chapter.
+
+:::
+
+### Recommended capabilities
+
+Relying on the Identity federation conceptually changes ways of identity
+resource management. This makes it impossible to fulfill them as MUST
+requirements. This chapter describes remaining capabilities of the initial
+Domain Manager as SHOULD implement.
+
+#### Domains usage
+
+It is strongly suggested to rely on the Domain concept of Keystone to implement
+multi-tenancy.
+
+Usage of domains by itself allows to implement form of self-service management
+by the customer. Only identity resources are owned by domains (with projects
+being also identity resources). Other services use projects to for resources
+isolation. They do not need to be domain aware.
+
+Using domains allows implementing [domain
+limits](https://docs.openstack.org/keystone/latest/admin/unified-limits.html#domain-limits)
+which allow to set a global resources limit for the customer. Without domains
+specific limits artificial control of the overall customer consumption must be
+implemented.
+
+#### User management
+
+User management (creation, activation, deactivation, deletion) SHOULD be
+possible using OpenStack APIs.
+
+When an external IdP is being used (IdP federation) there is still an
+expectation that local users may be required by customers. As such creation of
+users (pre-creating federated users or regular local users) within customer
+domain SHOULD me possible. Keystone does not allow certain operations on
+federated users (i.e. password change, MFA, name) as such allowing customers to
+manage users using OpenStack APIs should not conflict with any additional
+requirements.
+
+Security requirements on the customer side or on the CSP side to only allow
+federated users to consume platform services was used as the limitating factor
+forcing degrading of the capability requirement.
+
+#### Group management
+
+Management of groups SHOULD be possible using OpenStack APIs.
+
+In case of federated Identities there it is possible that groups on the IdP
+side do not match groups on the cloud provider side. In addition to that there
+might be a need to combine federated and local users. This would only be
+possible when groups are managed by the OpenStack.
+
+It is advised to keep user groups as mapped entities between external systems
+of CSP and Keystone. Upon user login (or using SCIM) user group relation may be
+synchronized between both platforms.
+
+#### Project deletion
+
+As described above project deletion may be implemented differently by CSPs.
+There are few ways of achieving that:
+
+- Forbid project deletion when resources (i.e. VMs) are still provisioned
+inside of those projects. This scenario assumes that the customer is
+responsible for cleaning projects before their deletion.
+
+- Automatically purge all project resources by the CSP when project deletion
+request is received. In this scenario CSP is implementing custom functionality
+to delete all resources before deleting the project.
+
+- Leave orphant resources. In this scenario project is being deleted by the API
+with custom cleanup procedures being responsible for dropping orphant resources.
+
+Leaving orphant resources MAY NOT be allowed.
+
+Forbidding project deletion making customer responsible for the cleanup SHOULD
+be preferred since it allows preventing the accidental deletion of the
+resources. Supplementary methods for purging project resources MAY be offered by
+the CSP.