In today’s SaaS-driven world, multi-tenancy is a crucial capability for platforms that serve multiple customers, applications, or business units from a shared infrastructure. Apache Pulsar stands out from other messaging systems by offering first-class support for multi-tenant environments, allowing for secure and scalable isolation of data and workloads.

This post dives deep into how to implement and manage multi-tenant messaging architectures in Pulsar, with a focus on security, isolation, and best practices.

What is Multi-Tenancy in Pulsar?

Apache Pulsar is designed from the ground up with multi-tenancy in mind. It introduces hierarchical levels of Tenants, Namespaces, and Topics to structure and segregate workloads.

  • Tenant: Logical grouping for customers, business units, or apps
  • Namespace: Subdivision under a tenant for organizing topics and applying policies
  • Topic: Actual messaging endpoint

This structure provides fine-grained access control and logical isolation, allowing multiple tenants to coexist without interference.

Core Building Blocks for Isolation

Layer Purpose Example
Tenant Represents a tenant or customer tenantA
Namespace Grouping within tenant for policies tenantA/prod-namespace
Topic Stream endpoint persistent://tenantA/prod-namespace/orders

Each layer supports its own ACLs, quotas, and security policies.

Step 1: Create Tenants and Namespaces

Use the Pulsar Admin CLI or REST API:

# Create tenant
bin/pulsar-admin tenants create tenantA \
--allowed-clusters us-east-cluster \
--admin-roles tenantA-admin

# Create namespace
bin/pulsar-admin namespaces create tenantA/prod-namespace

Assign cluster-level access and admin roles at the tenant level.

Step 2: Configure Authentication and Authorization

Enable authentication in broker.conf:

authenticationEnabled=true
authenticationProviders=org.apache.pulsar.broker.authentication.AuthenticationProviderToken
authorizationEnabled=true
authorizationProvider=org.apache.pulsar.broker.authorization.PulsarAuthorizationProvider

Use JWT tokens or TLS certificates for identity:

# Assign role to namespace
bin/pulsar-admin namespaces grant-permission tenantA/prod-namespace \
--actions produce,consume \
--role tenantA-consumer

Step 3: Apply Resource Limits and Quotas

Namespaces can have message and throughput quotas:

# Limit to 100 MB/s publish rate
bin/pulsar-admin namespaces set-publish-rate tenantA/prod-namespace \
--msg-rate 1000 \
--byte-rate 104857600

Other controls include:

  • Subscription limits
  • Retention policies
  • Message TTL
  • Offload policies

This ensures tenants do not impact each other’s performance.

Step 4: Enable Audit Logging and Monitoring

Track access and usage per tenant:

  • Enable broker logs to capture producer/consumer activity
  • Use Prometheus metrics with Pulsar Exporter:
    • pulsar_subscriptions_count{tenant="tenantA"}
    • pulsar_throughput_in{tenant="tenantA"}

Visualize with Grafana dashboards per tenant/namespace.

Step 5: Isolate Tenants at the Broker or Cluster Level

For strict isolation:

  • Use dedicated clusters or brokers per tenant
  • Separate network namespaces or Kubernetes pods
  • Apply network policies and quotas

In Kubernetes, deploy per-tenant Pulsar clusters via Helm or Pulsar Operator for stronger boundaries.

Security Best Practices

✅ Use token-based authentication with expiration
✅ Implement RBAC policies using roles and scopes
✅ Limit access to namespaces, not just topics
✅ Enable TLS encryption for all data in transit
✅ Monitor per-tenant metrics and logs
✅ Separate staging and production namespaces per tenant

Common Use Cases

  • SaaS platforms offering messaging as a service
  • Multi-region applications with isolated environments
  • Business units using shared Pulsar infrastructure
  • Dev vs Prod isolation for microservice event streams

Conclusion

Apache Pulsar provides native support for multi-tenancy, making it an excellent choice for platforms that require tenant isolation, security, and scalable governance. With namespaces, RBAC, quotas, and flexible deployment options, Pulsar enables you to confidently serve multiple teams or customers without sacrificing control or performance.

By combining thoughtful design and proper policy enforcement, you can build a **robust, secure, multi