NLB
Public Network Load Balancer (NLB) for the Rack. When enabled, creates an internet-facing Layer 4 load balancer that services can opt into via the nlb: field in convox.yml. The existing Application Load Balancer (ALB) is unaffected — the NLB is a sidecar for TCP workloads that the ALB cannot handle.
| Default value | No |
| Allowed values | Yes, No |
Use Cases
- Exposing non-HTTP TCP protocols (MQTT, Redis, raw TCP gRPC, game servers)
- Portable static IPs via AWS Elastic IPs allocated per availability zone
- Low-overhead Layer 4 routing with source IP preservation at the VPC boundary
Prerequisites
Enabling NLB=Yes consumes 2 Elastic IPs on a 2-AZ Rack or 3 EIPs on an HA 3-AZ Rack. Private=Yes Racks already consume 2-3 EIPs for NAT gateways. Before enabling NLB on a Private=Yes HA 3-AZ Rack (total 6 EIPs), verify your account has quota headroom:
$ aws service-quotas get-service-quota \
--service-code ec2 --quota-code L-0263D0A3
The default regional quota is 5 EIPs. Request an increase through AWS Service Quotas if needed before enabling.
Additional Information
When set to Yes, Convox provisions an AWS::ElasticLoadBalancingV2::LoadBalancer of type network with SubnetMappings that attach the EIPs to the Rack's public subnets. Services opt in per-port using the nlb: field in convox.yml. Each declared port becomes a dedicated AWS::ElasticLoadBalancingV2::Listener + TargetGroup on the shared Rack NLB.
$ convox rack params set NLB=Yes
NLB provisioning typically takes 5-10 minutes. Check status with convox rack; the output will show the NLB DNS name and allocated EIPs once CloudFormation completes.
This parameter cannot be enabled on an InternalOnly Rack. Use NLBInternal instead.
Disable
Before setting NLB=No, remove the nlb: field from every service in every app deployed on the Rack and redeploy each. The disable will be refused with a list of blocking apps otherwise. This is intentional — disabling the NLB while apps still reference it would break those apps' next deploy via Fn::ImportValue resolution failure.
Known Limitations (v1)
See Network Load Balancing for the full v1 limitations list.
See Also
