feat: infer service account groups for tenant tiers dynamically

Service account groups were expected to be defined in the config, making tenant-specific
namespace projections less flexible. This change ensures that tier-related
service accounts are inferred automatically per tenant, reducing manual config and
potential drift.

- Removed hardcoded service account group mappings from the dev overlay configmap
- Added dynamic projection of service account groups in tier mapper
- Extended test coverage to validate group inference for free tier service accounts

Signed-off-by: Bartosz Majsak <bartosz.majsak@gmail.com>

Author: bartoszmajsak

maas-api/deploy/overlays/dev/resources/tier-mapping-configmap.yaml

@@ -9,17 +9,14 @@ data:
       level: 1
       groups:
       - system:authenticated
-      - system:serviceaccount:openshift-ai-inference-tier-free
     - name: premium
       description: Premium tier for paying customers
       level: 10
       groups:
-      - system:serviceaccount:openshift-ai-inference-tier-premium
       - premium-users
     - name: enterprise
       description: Enterprise tier for corporate customers
       level: 20
       groups:
-      - system:serviceaccount:openshift-ai-inference-tier-enterprise
       - enterprise-users
       - admin-users

maas-api/internal/tier/mapper.go

@@ -52,12 +52,16 @@ func (m *Mapper) Namespaces(ctx context.Context) map[string]string {
 	namespaces := make(map[string]string, len(tiers))
 
 	for _, tier := range tiers {
-		namespaces[tier.Name] = fmt.Sprintf("%s-tier-%s", m.tenantName, tier.Name)
+		namespaces[tier.Name] = m.projectedNsName(tier)
 	}
 
 	return namespaces
 }
 
+func (m *Mapper) projectedNsName(tier Tier) string {
+	return fmt.Sprintf("%s-tier-%s", m.tenantName, tier.Name)
+}
+
 // GetTierForGroups returns the highest level tier for a user with multiple group memberships.
 //
 // Returns error if no groups provided or no groups found in any tier.
@@ -67,6 +71,7 @@ func (m *Mapper) GetTierForGroups(ctx context.Context, groups ...string) (string
 		return "", fmt.Errorf("no groups provided")
 	}
 
+	// system:serviceaccount:openshift-ai-inference-tier-enterprise
 	tiers, err := m.loadTierConfig(ctx)
 	if err != nil {
 		if errors.IsNotFound(err) {
@@ -109,5 +114,10 @@ func (m *Mapper) loadTierConfig(ctx context.Context) ([]Tier, error) {
 		return nil, fmt.Errorf("failed to parse tier configuration: %w", err)
 	}
 
+	for i := range tiers {
+		tier := &tiers[i]
+		tier.Groups = append(tier.Groups, fmt.Sprintf("system:serviceaccount:%s", m.projectedNsName(*tier)))
+	}
+
 	return tiers, nil
 }

maas-api/internal/tier/mapper_test.go

@@ -38,6 +38,12 @@ func TestMapper_GetTierForGroups(t *testing.T) {
 			expectedTier: "free",
 			description:  "User belongs to only free tier group",
 		},
+		{
+			name:         "inferred SA group - free tier",
+			groups:       []string{"system:serviceaccount:test-tenant-tier-free"},
+			expectedTier: "free",
+			description:  "User belongs to only free tier group",
+		},
 		{
 			name:         "single group - premium tier",
 			groups:       []string{"premium-users"},