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Kubernetes Ingress solution

September 14, 2021
Contributed by: 
S C

This topic provides an overview of the Kubernetes Ingress solution provided by Citrix and explains the benefits.

What is Kubernetes Ingress?

When you are running an application inside a Kubernetes cluster, you need to provide a way for external users to access the applications from outside the Kubernetes cluster. Kubernetes provides an object called Ingress that provides the most effective way to expose multiple services using a stable IP address. A Kubernetes ingress object is always associated with one or more services and acts as a single-entry point for external users to access services running inside the cluster.

The following diagram explains how Kubernetes Ingress works. Kubernetes Ingress

Kubernetes Ingress implementation consists of the following components:

  • Ingress resource. An Ingress resource allows you to define rules for accessing the applications from outside of the cluster.

  • Ingress controller. An Ingress controller is an application deployed inside the cluster that interprets rules defined in the Ingress. Ingress controller converts the Ingress rules into configuration instructions for a load balancing application integrated with the cluster. The load balancer can be a software application running inside your Kubernetes cluster or a hardware appliance running outside the cluster.

  • Ingress device. An Ingress device is a load balancing application like Citrix ADC CPX, VPX, or MPX which performs load balancing according to the configuration instructions provided by the Ingress controller.

What is the Kubernetes Ingress solution from Citrix?

In this solution, Citrix provides an implementation of Kubernetes Ingress controller to manage and route traffic into your Kubernetes cluster using Citrix ADCs (Citrix ADC CPX, VPX, or MPX). The Citrix ingress controller integrates Citrix ADCs with your Kubernetes environment and configures Citrix ADC CPX, VPX, or MPX according to the Ingress rules.

Standard Kubernetes Ingress solutions provide load balancing only at layer 7 (HTTP or HTTPS traffic). Some times, you need to expose many legacy applications which rely on TCP or UDP or applications and need a way to load balance those applications. Citrix Kubernetes Ingress solution provides TCP, TCP-SSL, and UDP traffic support apart from the standard HTTP or HTTPS Ingress. Also, it works seamlessly across multiple clouds or on-premises data centers.

Citrix ADC provides enterprise-grade traffic management policies like rewrite and responder policies for efficiently load balancing traffic at layer 7. However, Kubernetes Ingress lacks such enterprise-grade traffic management policies. With the Kubernetes Ingress solution from Citrix, you can apply rewrite and responder policies for application traffic in a Kubernetes environment using CRDs provided by Citrix.

The Kubernetes Ingress solution from Citrix also supports automated canary deployment for your CI/CD application pipeline. In this solution, Citrix ADC is integrated with the Spinnaker platform and acts as a source for providing accurate metrics for analyzing Canary deployment using Kayenta. After analyzing the metrics, Kayenta generates an aggregate score for the canary and decides to promote or fail the Canary version. You can also regulate traffic distribution to the Canary version using the Citrix ADC policy infrastructure.

The following table summarizes the benefits offered by the Ingress solution from Citrix over Kubernetes Ingress.

Features Kubernetes Ingress Ingress Solution from Citrix
HTTP and HTTPs support Yes Yes
URL routing​ ​ Yes Yes
TLS Yes Yes
Load balancing Yes Yes
TCP, TCP-SSL​ No Yes
UDP No Yes
HTTP/2 Yes Yes
Automated canary deployment support with CI/CD tools No Yes
Support for applying Citrix ADC rewrite and responder​ policies No Yes
Authentication (Open Authorization (OAuth), mutual TLS (mTLS)) No Yes
Support for applying Citrix Rate Limiting policies No Yes

Deployment options for Kubernetes Ingress solution

Kubernetes Ingress solution from Citrix provides you flexible architecture depending on how you want to manage your Citrix ADCs and Kubernetes environment.

Unified Ingress (single-tier)

In a unified Ingress (single-tier) architecture, a Citrix MPX or VPX device deployed outside the Kubernetes cluster is integrated with the Kubernetes environment using the Citrix ingress controller. The Citrix ingress controller is deployed as a pod in the Kubernetes cluster and automates the configuration of Citrix ADCs based on changes to the microservices or the Ingress resources. The Citrix ADC device performs functions like load balancing, TLS termination, and HTTP or TCP protocol optimizations on inbound traffic and then routes the traffic to the correct microservice within a Kubernetes cluster. This architecture suits best in scenarios where the same team manages the Kubernetes platform and other networking infrastructure including application delivery controllers (ADCs).

The following diagram shows a deployment using the unified Ingress architecture.

Single-tier

A unified Ingress solution provides the following key benefits:

  • Provides a way to extend the capabilities of your existing Citrix ADC infrastructure to the Kubernetes environment
  • Enables you to apply traffic management policies for inbound traffic
  • Provides a simplified architecture suitable for network-savvy DevOps teams
  • Supports multitenancy

Dual-tier Ingress

In a dual-tier architecture, Citrix ADC (MPX or VPX) deployed outside the Kubernetes cluster acts at tier 1 and load balances North-South traffic to Citrix ADC CPXs running inside the cluster. Citrix ADC CPX acts at tier 2 and performs load balancing for microservices inside the Kubernetes cluster.

In scenarios where separate teams manage the Kubernetes platform and the network infrastructure, the dual-tier architecture is most suitable.

Networking teams use tier 1 Citrix ADC for use cases such as GSLB, TLS termination on the hardware platform, and TCP load balancing. Kubernetes platform teams can use tier 2 Citrix ADC (CPX) for Layer 7 (HTTP/HTTPS) load balancing, mutual TLS, and observability or monitoring of microservices. The tier 2 Citrix ADC (CPX) can have a different software release version than the tier 1 Citrix ADC to accommodate newly available capabilities.

The following diagram shows a deployment with dual-tier architecture.

Dual-tier

A dual-tier Ingress provides the following key benefits:

  • Ensures high velocity of application development for developers or platform teams
  • Enables applying developer driven traffic management policies for microservices inside the Kubernetes cluster
  • Enables cloud scale and multitenancy

For more information, see the Citrix ingress controller documentation.

Getting started

To get started with the Kubernetes Ingress solution from Citrix, you can try out the following examples:

Kubernetes Ingress solution
September 14, 2021
Contributed by: 
S C
September 14, 2021
Contributed by: 
S C

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