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Update health checks docs for tproxy (#10419) 

* Update health checks docs for tproxy
Co-authored-by: Iryna Shustava <ishustava@users.noreply.github.com>
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Kyle Schochenmaier 2021-06-21 13:48:07 -05:00 committed by GitHub
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@ -6,33 +6,21 @@ description: Configuring Kubernetes Health Checks
# Kubernetes Health Checks in Consul on Kubernetes
-> 0.26+: This feature is available in consul-helm versions 0.26 and higher and is defaulted on.
To disable it, set `connectInject.healthChecks.enabled: false`.
-> **Note**: As of consul-k8s `v0.26.0-beta1` and Consul Helm `v0.32.0-beta1`, syncing of the Kubernetes readiness status
is always on, and turning it off is no longer configurable.
~> This topic requires familiarity with [Kubernetes Health Checks](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/).
This page describes how to enable Consul on Kubernetes to sync the Kubernetes readiness status to Consul for service mesh uses cases.
This page describes how Consul on Kubernetes will sync the status of Kubernetes health probes of a pod to Consul for service mesh use cases.
Health check synchronization with Consul is done automatically whenever `connectInject.enabled` is `true`.
When deploying your Helm chart, you can provide Helm with a custom yaml file that contains your environment configuration.
Enabling health checks is done via the `healthChecks` stanza under `connectInject`.
For each Kubernetes pod that is connect-injected the following will be configured:
The minimal configuration required to enable health check synchronization with Consul for service mesh traffic is:
1. A [TTL health check](/docs/discovery/checks#ttl) is registered within Consul.
The Consul health check's state will reflect the pod's readiness status,
which is the combination of all Kubernetes probes registered with the pod.
```yaml
global:
name: consul
connectInject:
enabled: true
healthChecks:
enabled: true
```
1. If the pod is utilizing [Transparent Proxy](/docs/connect/transparent-proxy) mode, the mutating webhook will mutate all `http` based Startup, Liveness, and Readiness probes in the pod to redirect through the Envoy proxy.
This is done with [`ExposePaths` configuration](/docs/connect/registration/service-registration#expose-paths-configuration-reference) for each probe so that kubelet can access the endpoint through the Envoy proxy.
When `enabled: true` is set, a [TTL health check](https://www.consul.io/docs/discovery/checks#ttl) will be registered within
Consul for each Kubernetes pod that is connect-injected. The Consul health check's state will reflect the pod's readiness
status, which is the combination of all Kubernetes probes registered with the pod.
~> The mutation behaviour can be disabled by either setting the `consul.hashicorp.com/transparent-proxy-overwrite-probes` pod annotation to `false` or the `connectInject.defaultOverwriteProbes` Helm value to `false`.
When readiness probes are set for a pod, the status of the pod will be reflected within Consul and will cause Consul to redirect service
mesh traffic to the pod based on the pod's health. If the pod has failing health checks, Consul will no longer use
@ -42,8 +30,6 @@ then use the respective service instance for service mesh traffic.
In the case where no user defined health checks are assigned to a pod, the default behavior is that the Consul health check will
be marked `passing` until the pod becomes unready.
To disable the health check controller, set the configuration for `healthChecks` to `enabled: false`.
In this state no health checks will be associated with Consul for Kubernetes pods regardless of the pod's health probes.
-> It is highly recommended to [enable TLS](/docs/k8s/helm#v-global-tls-enabled) for all configurations which use healthChecks to mitigate any
security concerns should the pod network ever be compromised. The health checks controller makes calls across the network to Consul agents on all nodes so an attacker could potentially sniff ACL tokens if those calls are not encrypted.
-> It is highly recommended to [enable TLS](/docs/k8s/helm#v-global-tls-enabled) for all production configurations to mitigate any
security concerns should the pod network ever be compromised. The controller makes calls across the network to Consul agents on all
nodes so an attacker could potentially sniff ACL tokens *if those calls are not encrypted* via TLS.