mycasbin

Casbin Multi-Tenant Support

This package provides Casbin enforcer setup with multi-tenant support.

Migration Guide

Old Usage (Deprecated)

// ❌ Old: Direct database connection
enforcer := mycasbin.Setup(db, "")

For security-management (Local Database)

// ✅ security-management uses local database
enforcer, err := mycasbin.SetupForTenant(db, tenantID)

For Microservices (Remote Provider)

// ✅ Microservices use remote provider
provider := grpc_client.NewGrpcCasbinPolicyProvider(connManager)
enforcer, err := mycasbin.SetupWithProvider(provider, tenantID)

API Reference

SetupForTenant

func SetupForTenant(db *gorm.DB, tenantID int) (*casbin.SyncedEnforcer, error)

Creates an independent Casbin enforcer for the specified tenant.

Parameters:

• db: GORM database connection for the tenant's database
• tenantID: Tenant identifier (used for logging and to pin this tenant's policy-sync messages to a dedicated dispatch shard via the PSUBSCRIBE multiplexer)

Returns:

• *casbin.SyncedEnforcer: Tenant-specific enforcer instance
• error: Error if setup fails

Example:

db := getTenantDatabase(tenantID)
enforcer, err := mycasbin.SetupForTenant(db, tenantID)
if err != nil {
    return fmt.Errorf("租户 %d Casbin 初始化失败: %w", tenantID, err)
}

// Use enforcer for permission checks
allowed, err := enforcer.Enforce("user", "/api/v1/resource", "GET")

SetupWithProvider

func SetupWithProvider(provider PolicyProvider, tenantID int) (*casbin.SyncedEnforcer, error)

Creates a Casbin enforcer using a PolicyProvider instead of a database connection.

Parameters:

• provider: Policy provider implementation (typically gRPC-based)
• tenantID: Tenant identifier

Returns:

• *casbin.SyncedEnforcer: Enforcer with loaded policies
• error: Error if setup fails

Example:

provider := grpc_client.NewGrpcCasbinPolicyProvider(connManager)
enforcer, err := mycasbin.SetupWithProvider(provider, tenantID)
if err != nil {
    log.Fatalf("Casbin init failed: %v", err)
}

// Use enforcer for permission checks
allowed, err := enforcer.Enforce("user", "/api/v1/resource", "GET")

Usage:

• For microservices (evidence-management, file-storage-service, tenant-service)
• NOT for security-management (use SetupForTenant instead)

Setup (Deprecated)

func Setup(db *gorm.DB, _ string) *casbin.SyncedEnforcer

Legacy function for backward compatibility. Creates a single global enforcer.

Deprecated: Use SetupForTenant instead for proper multi-tenant support.

Redis Watcher (PSUBSCRIBE Multiplexer)

Policy synchronization uses a single PSUBSCRIBE connection (the CasbinWatcherMux singleton in watcher_mux.go) rather than one subscriber per tenant. New tenants match the wildcard pattern automatically, with zero additional connection cost.

Three-client Redis model

The watcher relies on jxt-core's split Redis client architecture (sdk/config/option_redis.go):

Channel naming

PUBLISH target  (per tenant):    /casbin/tenant/{tenantID}
PSUBSCRIBE pattern (all tenants): /casbin/tenant/*

How a policy change propagates

1. A tenant's policies are modified and the watcher publishes an MSG to /casbin/tenant/{tenantID} via Client #1.
2. Every instance's CasbinWatcherMux receives the message on the single Client #3 PSUBSCRIBE connection.
3. Each message is routed to a dedicated dispatch shard via tenantID % 8, so all messages for one tenant are processed strictly in publish order by a single worker (8 workers, each with a bounded 256-message queue).
4. The worker applies the update to that tenant's enforcer (LoadPolicy or an incremental SelfAdd/Remove/UpdatePolicy), skipping messages it published itself (UUID-based self-ignore).

Wire compatibility

The MSG payload is byte-for-byte compatible with go-admin-team/redis-watcher/v2, so instances running the old per-tenant watcher and instances running the mux can coexist in the same Redis during a rolling upgrade.

Lifecycle

• InitCasbinWatcherMux(pubClient, subClient) — starts the background listener and the 8-shard worker pool. Idempotent (sync.Once); safe to call from concurrent goroutines.
• ShutdownCasbinWatcherMux() — drains the workers and listener so Redis clients can be closed safely. Wired into Application.Close().
• The subscription reconnects with exponential backoff (1s → 30s cap), reset to the minimum after each successfully received message.

Graceful Degradation

• If Redis is unavailable during SetupForTenant, the enforcer is still created successfully.
• A warning is logged, but the tenant can still function.
• PUBLISH becomes a no-op when Redis is absent, so policy changes won't auto-synchronize until Redis is available.

Testing

Run tests:

# Unit tests (mock-based)
go test ./sdk/pkg/casbin/... -short

# Integration tests (requires test database)
go test ./sdk/pkg/casbin/... -v

# With coverage
go test ./sdk/pkg/casbin/... -cover -coverprofile=coverage.out

Known Issues

None (as of Stage 3). All multi-tenant isolation issues have been fixed.

Roadmap

• Stage 1: Remove singleton, add SetupForTenant ✅
• Stage 2: Redis Watcher per-tenant isolation ✅
• Stage 3: PSUBSCRIBE multiplexer — single-connection all-tenant sync with 8-shard dispatch preserving per-tenant ordering ✅
• Stage 4: Update security-management to use new APIs (pending)

Related Documents

• Casbin Multi-Tenant Isolation Issue Analysis
• Fix Implementation Plan