open-consul/website/content/docs/k8s/index.mdx

---
layout: docs
page_title: Kubernetes
description: >-
  Consul has many integrations with Kubernetes. You can deploy Consul to
  Kubernetes using the Helm chart, sync services between Consul and Kubernetes,
  automatically secure Pod communication with Connect, and more. This section
  documents the official integrations between Consul and Kubernetes.
---

# Kubernetes

Consul has many integrations with Kubernetes. You can deploy Consul
to Kubernetes using the [Helm chart](/docs/k8s/installation/install#helm-chart-installation) or [Consul K8s CLI](/docs/k8s/installation/install#consul-k8s-cli-installation), sync services between Consul and
Kubernetes, run Consul Connect Service Mesh, and more.
This section documents the official integrations between Consul and Kubernetes.

## Use Cases

**Running a Consul server cluster:** The Consul server cluster can run directly
on Kubernetes. This can be used by both nodes within Kubernetes as well as
nodes external to Kubernetes, as long as they can communicate to the server
nodes via the network.

**Running Consul clients:** Consul clients can run as pods on every node
and expose the Consul API to running pods. This enables many Consul tools
such as envconsul, consul-template, and more to work on Kubernetes since a
local agent is available. This will also register each Kubernetes node with
the Consul catalog for full visibility into your infrastructure.

**Consul Connect Service Mesh:**
Consul can automatically inject the [Consul Connect](/docs/connect)
sidecar into pods so that they can accept and establish encrypted
and authorized network connections via mutual TLS. And because Connect
can run anywhere, pods can also communicate with external services (and
vice versa) over a fully encrypted connection.

**Service sync to enable Kubernetes and non-Kubernetes services to communicate:**
Consul can sync Kubernetes services with its own service registry. This allows
Kubernetes services to use native Kubernetes service discovery to discover
and connect to external services registered in Consul, and for external services
to use Consul service discovery to discover and connect to Kubernetes services.

**And more!** Consul can run directly on Kubernetes, so in addition to the
native integrations provided by Consul itself, any other tool built for
Kubernetes can choose to leverage Consul.

## Architecture

Consul runs on Kubernetes with the same
[architecture](/docs/internals/architecture)
as other platforms. There are some benefits Kubernetes can provide
that eases operating a Consul cluster and we document those below. The standard
[production deployment guide](https://learn.hashicorp.com/consul/datacenter-deploy/deployment-guide) is still an
important read even if running Consul within Kubernetes.

Each section below will outline the different components of running Consul
on Kubernetes and an overview of the resources that are used within the
Kubernetes cluster.

### Server Agents

The server agents are run as a **StatefulSet**, using persistent volume
claims to store the server state. This also ensures that the
[node ID](/docs/agent/config/cli-flags#_node_id) is persisted so that servers
can be rescheduled onto new IP addresses without causing issues. The server agents
are configured with
[anti-affinity](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity)
rules so that they are placed on different nodes. A readiness probe is
configured that marks the pod as ready only when it has established a leader.

A **Service** is registered to represent the servers and expose the various
ports. The DNS address of this service is used to join the servers to each
other without requiring any other access to the Kubernetes cluster. The
service is configured to publish non-ready endpoints so that it can be used
for joining during bootstrap and upgrades.

Additionally, a **PodDisruptionBudget** is configured so the Consul server
cluster maintains quorum during voluntary operational events. The maximum
unavailable is `(n/2)-1` where `n` is the number of server agents.

-> **Note:** Kubernetes and Helm do not delete Persistent Volumes or Persistent
Volume Claims when a
[StatefulSet is deleted](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#stable-storage),
so this must done manually when removing servers.

### Client Agents

The client agents are run as a **DaemonSet**. This places one agent
(within its own pod) on each Kubernetes node.
The clients expose the Consul HTTP API via a static port (8500)
bound to the host port. This enables all other pods on the node to connect
to the node-local agent using the host IP that can be retrieved via the
Kubernetes downward API. See
[accessing the Consul HTTP API](/docs/k8s/installation/install#accessing-the-consul-http-api)
for an example.

We do not use a **NodePort** Kubernetes service because requests to node ports get randomly routed
to any pod in the service and we need to be able to route directly to the Consul
client running on our node.

-> **Note:** There is no way to bind to a local-only
host port. Therefore, any other node can connect to the agent. This should be
considered for security. For a properly production-secured agent with TLS
and ACLs, this is safe.

We run Consul clients as a **DaemonSet** instead of running a client in each
application pod as a sidecar because this would turn
a pod into a "node" in Consul and also causes an explosion of resource usage
since every pod needs a Consul agent. Service registration should be handled via the
catalog syncing feature with Services rather than pods.

-> **Note:** Due to a limitation of anti-affinity rules with DaemonSets,
a client-mode agent runs alongside server-mode agents in Kubernetes. This
duplication wastes some resources, but otherwise functions perfectly fine.

## Getting Started With Consul and Kubernetes

There are several ways to try Consul with Kubernetes in different environments.

**Tutorials**

- The [Getting Started with Consul Service Mesh track](https://learn.hashicorp.com/tutorials/consul/service-mesh?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS)
  provides guidance for installing Consul as service mesh for Kubernetes using the Helm
  chart, deploying services in the service mesh, and using intentions to secure service
  communications.

- The [Migrate to Microservices with Consul Service Mesh on Kubernetes](https://learn.hashicorp.com/collections/consul/microservices?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS)
  collection uses an example application written by a fictional company to illustrate why and how organizations can
  migrate from monolith to microservices using Consul service mesh on Kubernetes. The case study in this collection
  should provide information valuable for understanding how to develop services that leverage Consul during any stage
  of your microservices journey.

- The [Consul and Minikube guide](https://learn.hashicorp.com/tutorials/consul/kubernetes-minikube?utm_source=consul.io&utm_medium=docs) is a quick step-by-step guide for deploying Consul with the official Helm chart on a local instance of Minikube.

- Review production best practices and cloud-specific configurations for deploying Consul on managed Kubernetes runtimes.

  - The [Consul on Azure Kubernetes Service (AKS) tutorial](https://learn.hashicorp.com/tutorials/consul/kubernetes-aks-azure?utm_source=consul.io&utm_medium=docs) is a complete step-by-step guide on how to deploy Consul on AKS. The guide also allows you to practice deploying two microservices.
  - The [Consul on Amazon Elastic Kubernetes Service (EKS) tutorial](https://learn.hashicorp.com/tutorials/consul/kubernetes-eks-aws?utm_source=consul.io&utm_medium=docs) is a complete step-by-step guide on how to deploy Consul on EKS. Additionally, it provides guidance on interacting with your datacenter with the Consul UI, CLI, and API.
  - The [Consul on Google Kubernetes Engine (GKE) tutorial](https://learn.hashicorp.com/tutorials/consul/kubernetes-gke-google?utm_source=consul.io&utm_medium=docs) is a complete step-by-step guide on how to deploy Consul on GKE. Additionally, it provides guidance on interacting with your datacenter with the Consul UI, CLI, and API.

- The [Consul and Kubernetes Reference Architecture](https://learn.hashicorp.com/tutorials/consul/kubernetes-reference-architecture?utm_source=consul.io&utm_medium=docs) guide provides recommended practices for production.

- The [Consul and Kubernetes Deployment](https://learn.hashicorp.com/tutorials/consul/kubernetes-deployment-guide?utm_source=consul.io&utm_medium=docs) tutorial covers the necessary steps to install and configure a new Consul cluster on Kubernetes in production.

- The [Secure Consul and Registered Services on Kubernetes](https://learn.hashicorp.com/tutorials/consul/kubernetes-secure-agents?in=consul/kubernetes) tutorial covers
  the necessary steps to secure a Consul cluster running on Kubernetes in production.

- The [Layer 7 Observability with Consul Service Mesh](https://learn.hashicorp.com/tutorials/consul/kubernetes-layer7-observability) tutorial covers monitoring a
  Consul service mesh running on Kubernetes with Prometheus and Grafana.

**Documentation**

- [Installing Consul](/docs/k8s/installation/install) covers how to install Consul using the Helm chart.
- [Helm Chart Reference](/docs/k8s/helm) describes the different options for configuring the Helm chart.