Skip to content
2023 API Summit Hackathon: Experiment with AI for APIs (August 28 - September 27) Learn More →
Kong Logo | Kong Docs Logo
search
  • We're Hiring!
  • Docs
    • Kong Gateway
      Lightweight, fast, and flexible cloud-native API gateway
      Kong Konnect
      Single platform for SaaS end-to-end connectivity
      Kong Mesh
      Enterprise service mesh based on Kuma and Envoy
      decK
      Helps manage Kong’s configuration in a declarative fashion
      Kong Ingress Controller
      Works inside a Kubernetes cluster and configures Kong to proxy traffic
      Kong Gateway Operator
      Manage your Kong deployments on Kubernetes using YAML Manifests
      Insomnia
      Collaborative API development platform
      Kuma
      Open-source distributed control plane with a bundled Envoy Proxy integration
  • API Specs
  • Plugin Hub
    • Explore the Plugin Hub
      View all plugins View all plugins View all plugins arrow image
    • Functionality View all View all arrow image
      View all plugins
      Authentication's icon
      Authentication
      Protect your services with an authentication layer
      Security's icon
      Security
      Protect your services with additional security layer
      Traffic Control's icon
      Traffic Control
      Manage, throttle and restrict inbound and outbound API traffic
      Serverless's icon
      Serverless
      Invoke serverless functions in combination with other plugins
      Analytics & Monitoring's icon
      Analytics & Monitoring
      Visualize, inspect and monitor APIs and microservices traffic
      Transformations's icon
      Transformations
      Transform request and responses on the fly on Kong
      Logging's icon
      Logging
      Log request and response data using the best transport for your infrastructure
  • Support
  • Community
  • Kong Academy
Get a Demo Start Free Trial
Kong Ingress Controller
2.6.x
  • Home icon
  • Kong Ingress Controller
  • Concepts
  • High-availability, Scaling, and Robustness
github-edit-pageEdit this page
report-issueReport an issue
  • Kong Gateway
  • Kong Konnect
  • Kong Mesh
  • Plugin Hub
  • decK
  • Kong Ingress Controller
  • Kong Gateway Operator
  • Insomnia
  • Kuma

  • Docs contribution guidelines
  • 2.11.x (latest)
  • 2.10.x
  • 2.9.x
  • 2.8.x
  • 2.7.x
  • 2.6.x
  • 2.5.x
  • 2.4.x
  • 2.3.x
  • 2.2.x
  • 2.1.x
  • 2.0.x
  • 1.3.x
  • 1.2.x
  • 1.1.x
  • 1.0.x
enterprise-switcher-icon Switch to OSS
On this pageOn this page
  • High availability
    • Leader election
  • Scaling
You are browsing documentation for an outdated version. See the latest documentation here.

High-availability, Scaling, and Robustness

High availability

The Kong Ingress Controller is designed to be reasonably easy to operate and be highly available, meaning, when some expected failures do occur, the Controller should be able to continue to function with minimum possible service disruption.

The Kong Ingress Controller is composed of two parts: 1. Kong, which handles the requests, 2. Controller, which configures Kong dynamically.

Kong itself can be deployed in a highly-available manner by deploying multiple instances (or pods). Kong nodes are state-less, meaning a Kong pod can be terminated and restarted at any point of time.

The controller itself can be stateful or stateless, depending on if a database is being used or not.

If a database is not used, then the Controller and Kong are deployed as co-located containers in the same pod and each controller configures the Kong container that it is running with.

For cases when a database is necessary, the Controllers can be deployed on multiple zones to provide redundancy. In such a case, a leader election process will elect one instance as a leader, which will manipulate Kong’s configuration.

Leader election

Multiple Kong Ingress Controller instances elect a leader when connected to a database-backed cluster. This ensures that only a single controller pushes configuration to Kong’s database to avoid potential conflicts and race conditions.

When a leader controller shuts down, other instances will detect that there is no longer a leader, and one will promote itself to the leader.

For this reason, the controller needs permission to create a ConfigMap. By default, the permission is given at Cluster level, but it can be narrowed down to a single namespace (using Role and RoleBinding) for a stricter RBAC policy.

It also needs permission to read and update this ConfigMap. This permission can be specific to the ConfigMap that is being used for leader-election purposes. The name of the ConfigMap is derived from the value of election-id CLI flag (default: ingress-controller-leader) and ingress-class (default: kong) as: “-". For example, the default ConfigMap that is used for leader election will be `ingress-controller-leader-kong`, and it will be present in the same namespace that the controller is deployed in.

Scaling

Kong is designed to be horizontally scalable, meaning as traffic increases, multiple instances of Kong can be deployed to handle the increase in load.

The configuration is either pumped into Kong directly via the Ingress Controller or loaded via the database. Kong containers can be considered stateless as the configuration is either loaded from the database (and cached heavily in-memory) or loaded in-memory directly via a config file.

One can use a HorizontalPodAutoscaler (HPA) based on metrics like CPU utilization, bandwidth being used, total request count per second to dynamically scale Kong Ingress Controller as the traffic profile changes.

Thank you for your feedback.
Was this page useful?
Too much on your plate? close cta icon
More features, less infrastructure with Kong Konnect. 1M requests per month for free.
Try it for Free
  • Kong
    THE CLOUD CONNECTIVITY COMPANY

    Kong powers reliable digital connections across APIs, hybrid and multi-cloud environments.

    • Company
    • Customers
    • Events
    • Investors
    • Careers Hiring!
    • Partners
    • Press
    • Contact
  • Products
    • Kong Konnect
    • Kong Gateway
    • Kong Mesh
    • Get Started
    • Pricing
  • Resources
    • eBooks
    • Webinars
    • Briefs
    • Blog
    • API Gateway
    • Microservices
  • Open Source
    • Install Kong Gateway
    • Kong Community
    • Kubernetes Ingress
    • Kuma
    • Insomnia
  • Solutions
    • Decentralize
    • Secure & Govern
    • Create a Dev Platform
    • API Gateway
    • Kubernetes
    • Service Mesh
Star
  • Terms•Privacy
© Kong Inc. 2023