3.7. Optimizing routing
The OpenShift Container Platform HAProxy router scales to optimize performance.
3.7.1. Baseline Ingress Controller (router) performance
The OpenShift Container Platform Ingress Controller, or router, is the Ingress point for all external traffic destined for OpenShift Container Platform services.
When evaluating a single HAProxy router performance in terms of HTTP requests handled per second, the performance varies depending on many factors. In particular:
- HTTP keep-alive/close mode
- Route type
- TLS session resumption client support
- Number of concurrent connections per target route
- Number of target routes
- Back end server page size
- Underlying infrastructure (network/SDN solution, CPU, and so on)
While performance in your specific environment will vary, Red Hat lab tests on a public cloud instance of size 4 vCPU/16GB RAM. A single HAProxy router handling 100 routes terminated by backends serving 1kB static pages is able to handle the following number of transactions per second.
In HTTP keep-alive mode scenarios:
| Encryption | LoadBalancerService | HostNetwork |
|---|---|---|
| none | 21515 | 29622 |
| edge | 16743 | 22913 |
| passthrough | 36786 | 53295 |
| re-encrypt | 21583 | 25198 |
In HTTP close (no keep-alive) scenarios:
| Encryption | LoadBalancerService | HostNetwork |
|---|---|---|
| none | 5719 | 8273 |
| edge | 2729 | 4069 |
| passthrough | 4121 | 5344 |
| re-encrypt | 2320 | 2941 |
Default Ingress Controller configuration with ROUTER_THREADS=4 was used and two different endpoint publishing strategies (LoadBalancerService/HostNetwork) were tested. TLS session resumption was used for encrypted routes. With HTTP keep-alive, a single HAProxy router is capable of saturating 1 Gbit NIC at page sizes as small as 8 kB.
When running on bare metal with modern processors, you can expect roughly twice the performance of the public cloud instance above. This overhead is introduced by the virtualization layer in place on public clouds and holds mostly true for private cloud-based virtualization as well. The following table is a guide to how many applications to use behind the router:
| Number of applications | Application type |
|---|---|
| 5-10 | static file/web server or caching proxy |
| 100-1000 | applications generating dynamic content |
In general, HAProxy can support routes for 5 to 1000 applications, depending on the technology in use. Ingress Controller performance might be limited by the capabilities and performance of the applications behind it, such as language or static versus dynamic content.
Ingress, or router, sharding should be used to serve more routes towards applications and help horizontally scale the routing tier.
3.7.2. Ingress Controller (router) performance optimizations
OpenShift Container Platform no longer supports modifying Ingress Controller deployments by setting environment variables such as ROUTER_THREADS, ROUTER_DEFAULT_TUNNEL_TIMEOUT, ROUTER_DEFAULT_CLIENT_TIMEOUT, ROUTER_DEFAULT_SERVER_TIMEOUT, and RELOAD_INTERVAL.
You can modify the Ingress Controller deployment, but if the Ingress Operator is enabled, the configuration is overwritten.
