traefik/docs/configuration/backends/kubernetes.md

# Kubernetes Ingress Backend

Træfik can be configured to use Kubernetes Ingress as a backend configuration.

See also [Kubernetes user guide](/user-guide/kubernetes).

## Configuration

```toml
################################################################
# Kubernetes Ingress configuration backend
################################################################

# Enable Kubernetes Ingress configuration backend.
[kubernetes]

# Kubernetes server endpoint.
#
# Optional for in-cluster configuration, required otherwise.
# Default: empty
#
# endpoint = "http://localhost:8080"

# Bearer token used for the Kubernetes client configuration.
#
# Optional
# Default: empty
#
# token = "my token"

# Path to the certificate authority file.
# Used for the Kubernetes client configuration.
#
# Optional
# Default: empty
#
# certAuthFilePath = "/my/ca.crt"

# Array of namespaces to watch.
#
# Optional
# Default: all namespaces (empty array).
#
# namespaces = ["default", "production"]

# Ingress label selector to filter Ingress objects that should be processed.
#
# Optional
# Default: empty (process all Ingresses)
#
# labelselector = "A and not B"

# Disable PassHost Headers.
#
# Optional
# Default: false
#
# disablePassHostHeaders = true

# Enable PassTLSCert Headers.
#
# Optional
# Default: false
#
# enablePassTLSCert = true

# Override default configuration template.
#
# Optional
# Default: <built-in template>
#
# filename = "kubernetes.tmpl"
```

### `endpoint`

The Kubernetes server endpoint as URL.

When deployed into Kubernetes, Traefik will read the environment variables `KUBERNETES_SERVICE_HOST` and `KUBERNETES_SERVICE_PORT` to construct the endpoint.

The access token will be looked up in `/var/run/secrets/kubernetes.io/serviceaccount/token` and the SSL CA certificate in `/var/run/secrets/kubernetes.io/serviceaccount/ca.crt`.
Both are provided mounted automatically when deployed inside Kubernetes.

The endpoint may be specified to override the environment variable values inside a cluster.

When the environment variables are not found, Traefik will try to connect to the Kubernetes API server with an external-cluster client.
In this case, the endpoint is required.
Specifically, it may be set to the URL used by `kubectl proxy` to connect to a Kubernetes cluster using the granted autentication and authorization of the associated kubeconfig.

### `labelselector`

By default, Traefik processes all Ingress objects in the configured namespaces.
A label selector can be defined to filter on specific Ingress objects only.

See [label-selectors](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors) for details.

### TLS communication between Traefik and backend pods

Traefik automatically requests endpoint information based on the service provided in the ingress spec.
Although traefik will connect directly to the endpoints (pods), it still checks the service port to see if TLS communication is required.
If the service port defined in the ingress spec is 443, then the backend communication protocol is assumed to be TLS, and will connect via TLS automatically.

!!! note
    Please note that by enabling TLS communication between traefik and your pods, you will have to have trusted certificates that have the proper trust chain and IP subject name. 
    If this is not an option, you may need to skip TLS certificate verification.
    See the [InsecureSkipVerify](configuration/commons/#main-section) setting for more details.
    
## Annotations

### General annotations

The following general annotations are applicable on the Ingress object:

- `traefik.frontend.rule.type: PathPrefixStrip`
    Override the default frontend rule type. Default: `PathPrefix`.
- `traefik.frontend.priority: "3"`
    Override the default frontend rule priority.
- `traefik.frontend.redirect.entryPoint: https`:
    Enables Redirect to another entryPoint for that frontend (e.g. HTTPS).
- `traefik.frontend.redirect.regex: ^http://localhost/(.*)`:
    Redirect to another URL for that frontend. Must be set with `traefik.frontend.redirect.replacement`.
- `traefik.frontend.redirect.replacement: http://mydomain/$1`:
    Redirect to another URL for that frontend. Must be set with `traefik.frontend.redirect.regex`.
- `traefik.frontend.entryPoints: http,https`
    Override the default frontend endpoints.
- `traefik.frontend.passTLSCert: true`
    Override the default frontend PassTLSCert value. Default: `false`.
- `ingress.kubernetes.io/rewrite-target: /users`
    Replaces each matched Ingress path with the specified one, and adds the old path to the `X-Replaced-Path` header.
- `ingress.kubernetes.io/whitelist-source-range: "1.2.3.0/24, fe80::/16"`
    A comma-separated list of IP ranges permitted for access. all source IPs are permitted if the list is empty or a single range is ill-formatted.

!!! note
    Please note that `traefik.frontend.redirect.regex` and `traefik.frontend.redirect.replacement` do not have to be set if `traefik.frontend.redirect.entryPoint` is defined for the redirection (they will not be used in this case).

The following annotations are applicable on the Service object associated with a particular Ingress object:

- `traefik.backend.loadbalancer.method=drr`
    Override the default `wrr` load balancer algorithm.
- `traefik.backend.loadbalancer.stickiness=true`
    Enable backend sticky sessions.
- `traefik.backend.loadbalancer.stickiness.cookieName=NAME`
    Manually set the cookie name for sticky sessions.
- `traefik.backend.loadbalancer.sticky=true`
    Enable backend sticky sessions (DEPRECATED).
- `traefik.backend.circuitbreaker: <expression>`
    Set the circuit breaker expression for the backend.

### Security annotations

The following security annotations are applicable on the Ingress object:

|                        Annotation                        |                                                                                             Description                                                                                             |
| -------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ingress.kubernetes.io/allowed-hosts:EXPR`               | Provides a list of allowed hosts that requests will be processed. Format: `Host1,Host2`                                                                                                             |
| `ingress.kubernetes.io/custom-request-headers:EXPR`      | Provides the container with custom request headers that will be appended to each request forwarded to the container. Format: <code>HEADER:value&vert;&vert;HEADER2:value2</code>                    |
| `ingress.kubernetes.io/custom-response-headers:EXPR`     | Appends the headers to each response returned by the container, before forwarding the response to the client. Format: <code>HEADER:value&vert;&vert;HEADER2:value2</code>                           |
| `ingress.kubernetes.io/proxy-headers:EXPR`               | Provides a list of headers that the proxied hostname may be stored. Format:  `HEADER1,HEADER2`                                                                                                      |
| `ingress.kubernetes.io/ssl-redirect:true`                | Forces the frontend to redirect to SSL if a non-SSL request is sent.                                                                                                                                |
| `ingress.kubernetes.io/ssl-temporary-redirect:true`      | Forces the frontend to redirect to SSL if a non-SSL request is sent, but by sending a 302 instead of a 301.                                                                                         |
| `ingress.kubernetes.io/ssl-host:HOST`                    | This setting configures the hostname that redirects will be based on. Default is "", which is the same host as the request.                                                                         |
| `ingress.kubernetes.io/ssl-proxy-headers:EXPR`           | Header combinations that would signify a proper SSL Request (Such as `X-Forwarded-For:https`). Format: <code>HEADER:value&vert;&vert;HEADER2:value2</code>                                          |
| `ingress.kubernetes.io/hsts-max-age:315360000`           | Sets the max-age of the HSTS header.                                                                                                                                                                |
| `ingress.kubernetes.io/hsts-include-subdomains:true`      | Adds the IncludeSubdomains section of the STS  header.                                                                                                                                              |
| `ingress.kubernetes.io/hsts-preload:true`                | Adds the preload flag to the HSTS  header.                                                                                                                                                          |
| `ingress.kubernetes.io/force-hsts:false`                 | Adds the STS  header to non-SSL requests.                                                                                                                                                           |
| `ingress.kubernetes.io/frame-deny:false`                 | Adds the `X-Frame-Options` header with the value of `DENY`.                                                                                                                                         |
| `ingress.kubernetes.io/custom-frame-options-value:VALUE` | Overrides the `X-Frame-Options` header with the custom value.                                                                                                                                       |
| `ingress.kubernetes.io/content-type-nosniff:true`        | Adds the `X-Content-Type-Options` header with the value `nosniff`.                                                                                                                                  |
| `ingress.kubernetes.io/browser-xss-filter:true`          | Adds the X-XSS-Protection header with the value `1; mode=block`.                                                                                                                                    |
| `ingress.kubernetes.io/content-security-policy:VALUE`    | Adds CSP Header with the custom value.                                                                                                                                                              |
| `ingress.kubernetes.io/public-key:VALUE`                 | Adds pinned HTST public key header.                                                                                                                                                                 |
| `ingress.kubernetes.io/referrer-policy:VALUE`            | Adds referrer policy  header.                                                                                                                                                                       |
| `ingress.kubernetes.io/is-development:false`             | This will cause the `AllowedHosts`, `SSLRedirect`, and `STSSeconds`/`STSIncludeSubdomains` options to be ignored during development.<br>When deploying to production, be sure to set this to false. |

### Authentication

Is possible to add additional authentication annotations to the Ingress object.
The source of the authentication is a Secret object that contains the credentials.

- `ingress.kubernetes.io/auth-type`: `basic`
    Contains the authentication type. The only permitted type is `basic`.
- `ingress.kubernetes.io/auth-secret`: `mysecret`
    Contains the username and password with access to the paths defined in the Ingress object.

The secret must be created in the same namespace as the Ingress object.

The following limitations hold:

- The realm is not configurable; the only supported (and default) value is `traefik`.
- The Secret must contain a single file only.