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---
reviewers:
- bprashanth
title: Ingress
content_type: concept
weight: 40
---
<!-- overview -->
{{< feature-state for_k8s_version="v1.19" state="stable" >}}
{{< glossary_definition term_id="ingress" length="all" >}}
<!-- body -->
## Terminology
For clarity, this guide defines the following terms:
* Node: A worker machine in Kubernetes, part of a cluster.
* Cluster: A set of Nodes that run containerized applications managed by Kubernetes. For this example, and in most common Kubernetes deployments, nodes in the cluster are not part of the public internet.
* Edge router: A router that enforces the firewall policy for your cluster. This could be a gateway managed by a cloud provider or a physical piece of hardware.
* Cluster network: A set of links, logical or physical, that facilitate communication within a cluster according to the Kubernetes [networking model](/docs/concepts/cluster-administration/networking/).
* Service: A Kubernetes {{< glossary_tooltip term_id="service" >}} that identifies a set of Pods using {{< glossary_tooltip text="label" term_id="label" >}} selectors. Unless mentioned otherwise, Services are assumed to have virtual IPs only routable within the cluster network.
## What is Ingress?
[Ingress](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#ingress-v1-networking-k8s-io) exposes HTTP and HTTPS routes from outside the cluster to
{{< link text="services" url="/docs/concepts/services-networking/service/" >}} within the cluster.
Traffic routing is controlled by rules defined on the Ingress resource.
Here is a simple example where an Ingress sends all its traffic to one Service:
{{< mermaid >}}
graph LR;
client([client])-. Ingress-managed <br> load balancer .->ingress[Ingress];
ingress-->|routing rule|service[Service];
subgraph cluster
ingress;
service-->pod1[Pod];
service-->pod2[Pod];
end
classDef plain fill:#ddd,stroke:#fff,stroke-width:4px,color:#000;
classDef k8s fill:#326ce5,stroke:#fff,stroke-width:4px,color:#fff;
classDef cluster fill:#fff,stroke:#bbb,stroke-width:2px,color:#326ce5;
class ingress,service,pod1,pod2 k8s;
class client plain;
class cluster cluster;
{{</ mermaid >}}
An Ingress may be configured to give Services externally-reachable URLs, load balance traffic, terminate SSL / TLS, and offer name-based virtual hosting. An [Ingress controller](/docs/concepts/services-networking/ingress-controllers) is responsible for fulfilling the Ingress, usually with a load balancer, though it may also configure your edge router or additional frontends to help handle the traffic.
An Ingress does not expose arbitrary ports or protocols. Exposing services other than HTTP and HTTPS to the internet typically
uses a service of type [Service.Type=NodePort](/docs/concepts/services-networking/service/#nodeport) or
[Service.Type=LoadBalancer](/docs/concepts/services-networking/service/#loadbalancer).
## Prerequisites
You must have an [Ingress controller](/docs/concepts/services-networking/ingress-controllers) to satisfy an Ingress. Only creating an Ingress resource has no effect.
You may need to deploy an Ingress controller such as [ingress-nginx](https://kubernetes.github.io/ingress-nginx/deploy/). You can choose from a number of
[Ingress controllers](/docs/concepts/services-networking/ingress-controllers).
Ideally, all Ingress controllers should fit the reference specification. In reality, the various Ingress
controllers operate slightly differently.
{{< note >}}
Make sure you review your Ingress controller's documentation to understand the caveats of choosing it.
{{< /note >}}
## The Ingress resource
A minimal Ingress resource example:
{{< codenew file="service/networking/minimal-ingress.yaml" >}}
As with all other Kubernetes resources, an Ingress needs `apiVersion`, `kind`, and `metadata` fields.
The name of an Ingress object must be a valid
[DNS subdomain name](/docs/concepts/overview/working-with-objects/names#dns-subdomain-names).
For general information about working with config files, see [deploying applications](/docs/tasks/run-application/run-stateless-application-deployment/), [configuring containers](/docs/tasks/configure-pod-container/configure-pod-configmap/), [managing resources](/docs/concepts/cluster-administration/manage-deployment/).
Ingress frequently uses annotations to configure some options depending on the Ingress controller, an example of which
is the [rewrite-target annotation](https://github.com/kubernetes/ingress-nginx/blob/master/docs/examples/rewrite/README.md).
Different [Ingress controller](/docs/concepts/services-networking/ingress-controllers) support different annotations. Review the documentation for
your choice of Ingress controller to learn which annotations are supported.
The Ingress [spec](https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status)
has all the information needed to configure a load balancer or proxy server. Most importantly, it
contains a list of rules matched against all incoming requests. Ingress resource only supports rules
for directing HTTP(S) traffic.
### Ingress rules
Each HTTP rule contains the following information:
* An optional host. In this example, no host is specified, so the rule applies to all inbound
HTTP traffic through the IP address specified. If a host is provided (for example,
foo.bar.com), the rules apply to that host.
* A list of paths (for example, `/testpath`), each of which has an associated
backend defined with a `service.name` and a `service.port.name` or
`service.port.number`. Both the host and path must match the content of an
incoming request before the load balancer directs traffic to the referenced
Service.
* A backend is a combination of Service and port names as described in the
[Service doc](/docs/concepts/services-networking/service/) or a [custom resource backend](#resource-backend) by way of a {{< glossary_tooltip term_id="CustomResourceDefinition" text="CRD" >}}. HTTP (and HTTPS) requests to the
Ingress that matches the host and path of the rule are sent to the listed backend.
A `defaultBackend` is often configured in an Ingress controller to service any requests that do not
match a path in the spec.
### DefaultBackend {#default-backend}
An Ingress with no rules sends all traffic to a single default backend. The `defaultBackend` is conventionally a configuration option
of the [Ingress controller](/docs/concepts/services-networking/ingress-controllers) and is not specified in your Ingress resources.
If none of the hosts or paths match the HTTP request in the Ingress objects, the traffic is
routed to your default backend.
### Resource backends {#resource-backend}
A `Resource` backend is an ObjectRef to another Kubernetes resource within the
same namespace as the Ingress object. A `Resource` is a mutually exclusive
setting with Service, and will fail validation if both are specified. A common
usage for a `Resource` backend is to ingress data to an object storage backend
with static assets.
{{< codenew file="service/networking/ingress-resource-backend.yaml" >}}
After creating the Ingress above, you can view it with the following command:
```bash
kubectl describe ingress ingress-resource-backend
```
```
Name: ingress-resource-backend
Namespace: default
Address:
Default backend: APIGroup: k8s.example.com, Kind: StorageBucket, Name: static-assets
Rules:
Host Path Backends
---- ---- --------
*
/icons APIGroup: k8s.example.com, Kind: StorageBucket, Name: icon-assets
Annotations: <none>
Events: <none>
```
### Path types
Each path in an Ingress is required to have a corresponding path type. Paths
that do not include an explicit `pathType` will fail validation. There are three
supported path types:
* `ImplementationSpecific`: With this path type, matching is up to the
IngressClass. Implementations can treat this as a separate `pathType` or treat
it identically to `Prefix` or `Exact` path types.
* `Exact`: Matches the URL path exactly and with case sensitivity.
* `Prefix`: Matches based on a URL path prefix split by `/`. Matching is case
sensitive and done on a path element by element basis. A path element refers
to the list of labels in the path split by the `/` separator. A request is a
match for path _p_ if every _p_ is an element-wise prefix of _p_ of the
request path.
{{< note >}} If the last element of the path is a substring of the last
element in request path, it is not a match (for example: `/foo/bar`
matches`/foo/bar/baz`, but does not match `/foo/barbaz`). {{< /note >}}
### Examples
| Kind | Path(s) | Request path(s) | Matches? |
|--------|---------------------------------|-------------------------------|------------------------------------|
| Prefix | `/` | (all paths) | Yes |
| Exact | `/foo` | `/foo` | Yes |
| Exact | `/foo` | `/bar` | No |
| Exact | `/foo` | `/foo/` | No |
| Exact | `/foo/` | `/foo` | No |
| Prefix | `/foo` | `/foo`, `/foo/` | Yes |
| Prefix | `/foo/` | `/foo`, `/foo/` | Yes |
| Prefix | `/aaa/bb` | `/aaa/bbb` | No |
| Prefix | `/aaa/bbb` | `/aaa/bbb` | Yes |
| Prefix | `/aaa/bbb/` | `/aaa/bbb` | Yes, ignores trailing slash |
| Prefix | `/aaa/bbb` | `/aaa/bbb/` | Yes, matches trailing slash |
| Prefix | `/aaa/bbb` | `/aaa/bbb/ccc` | Yes, matches subpath |
| Prefix | `/aaa/bbb` | `/aaa/bbbxyz` | No, does not match string prefix |
| Prefix | `/`, `/aaa` | `/aaa/ccc` | Yes, matches `/aaa` prefix |
| Prefix | `/`, `/aaa`, `/aaa/bbb` | `/aaa/bbb` | Yes, matches `/aaa/bbb` prefix |
| Prefix | `/`, `/aaa`, `/aaa/bbb` | `/ccc` | Yes, matches `/` prefix |
| Prefix | `/aaa` | `/ccc` | No, uses default backend |
| Mixed | `/foo` (Prefix), `/foo` (Exact) | `/foo` | Yes, prefers Exact |
#### Multiple matches
In some cases, multiple paths within an Ingress will match a request. In those
cases precedence will be given first to the longest matching path. If two paths
are still equally matched, precedence will be given to paths with an exact path
type over prefix path type.
## Hostname wildcards
Hosts can be precise matches (for example “`foo.bar.com`”) or a wildcard (for
example “`*.foo.com`”). Precise matches require that the HTTP `host` header
matches the `host` field. Wildcard matches require the HTTP `host` header is
equal to the suffix of the wildcard rule.
| Host | Host header | Match? |
| ----------- |-------------------| --------------------------------------------------|
| `*.foo.com` | `bar.foo.com` | Matches based on shared suffix |
| `*.foo.com` | `baz.bar.foo.com` | No match, wildcard only covers a single DNS label |
| `*.foo.com` | `foo.com` | No match, wildcard only covers a single DNS label |
{{< codenew file="service/networking/ingress-wildcard-host.yaml" >}}
## Ingress class
Ingresses can be implemented by different controllers, often with different
configuration. Each Ingress should specify a class, a reference to an
IngressClass resource that contains additional configuration including the name
of the controller that should implement the class.
{{< codenew file="service/networking/external-lb.yaml" >}}
IngressClass resources contain an optional parameters field. This can be used to
reference additional implementation-specific configuration for this class.
#### Namespace-scoped parameters
{{< feature-state for_k8s_version="v1.21" state="alpha" >}}
`Parameters` field has a `scope` and `namespace` field that can be used to
reference a namespace-specific resource for configuration of an Ingress class.
`Scope` field defaults to `Cluster`, meaning, the default is cluster-scoped
resource. Setting `Scope` to `Namespace` and setting the `Namespace` field
will reference a parameters resource in a specific namespace:
{{< codenew file="service/networking/namespaced-params.yaml" >}}
### Deprecated annotation
Before the IngressClass resource and `ingressClassName` field were added in
Kubernetes 1.18, Ingress classes were specified with a
`kubernetes.io/ingress.class` annotation on the Ingress. This annotation was
never formally defined, but was widely supported by Ingress controllers.
The newer `ingressClassName` field on Ingresses is a replacement for that
annotation, but is not a direct equivalent. While the annotation was generally
used to reference the name of the Ingress controller that should implement the
Ingress, the field is a reference to an IngressClass resource that contains
additional Ingress configuration, including the name of the Ingress controller.
### Default IngressClass {#default-ingress-class}
You can mark a particular IngressClass as default for your cluster. Setting the
`ingressclass.kubernetes.io/is-default-class` annotation to `true` on an
IngressClass resource will ensure that new Ingresses without an
`ingressClassName` field specified will be assigned this default IngressClass.
{{< caution >}}
If you have more than one IngressClass marked as the default for your cluster,
the admission controller prevents creating new Ingress objects that don't have
an `ingressClassName` specified. You can resolve this by ensuring that at most 1
IngressClass is marked as default in your cluster.
{{< /caution >}}
## Types of Ingress
### Ingress backed by a single Service {#single-service-ingress}
There are existing Kubernetes concepts that allow you to expose a single Service
(see [alternatives](#alternatives)). You can also do this with an Ingress by specifying a
*default backend* with no rules.
{{< codenew file="service/networking/test-ingress.yaml" >}}
If you create it using `kubectl apply -f` you should be able to view the state
of the Ingress you added:
```bash
kubectl get ingress test-ingress
```
```
NAME CLASS HOSTS ADDRESS PORTS AGE
test-ingress external-lb * 203.0.113.123 80 59s
```
Where `203.0.113.123` is the IP allocated by the Ingress controller to satisfy
this Ingress.
{{< note >}}
Ingress controllers and load balancers may take a minute or two to allocate an IP address.
Until that time, you often see the address listed as `<pending>`.
{{< /note >}}
### Simple fanout
A fanout configuration routes traffic from a single IP address to more than one Service,
based on the HTTP URI being requested. An Ingress allows you to keep the number of load balancers
down to a minimum. For example, a setup like:
{{< mermaid >}}
graph LR;
client([client])-. Ingress-managed <br> load balancer .->ingress[Ingress, 178.91.123.132];
ingress-->|/foo|service1[Service service1:4200];
ingress-->|/bar|service2[Service service2:8080];
subgraph cluster
ingress;
service1-->pod1[Pod];
service1-->pod2[Pod];
service2-->pod3[Pod];
service2-->pod4[Pod];
end
classDef plain fill:#ddd,stroke:#fff,stroke-width:4px,color:#000;
classDef k8s fill:#326ce5,stroke:#fff,stroke-width:4px,color:#fff;
classDef cluster fill:#fff,stroke:#bbb,stroke-width:2px,color:#326ce5;
class ingress,service1,service2,pod1,pod2,pod3,pod4 k8s;
class client plain;
class cluster cluster;
{{</ mermaid >}}
would require an Ingress such as:
{{< codenew file="service/networking/simple-fanout-example.yaml" >}}
When you create the Ingress with `kubectl apply -f`:
```shell
kubectl describe ingress simple-fanout-example
```
```
Name: simple-fanout-example
Namespace: default
Address: 178.91.123.132
Default backend: default-http-backend:80 (10.8.2.3:8080)
Rules:
Host Path Backends
---- ---- --------
foo.bar.com
/foo service1:4200 (10.8.0.90:4200)
/bar service2:8080 (10.8.0.91:8080)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ADD 22s loadbalancer-controller default/test
```
The Ingress controller provisions an implementation-specific load balancer
that satisfies the Ingress, as long as the Services (`service1`, `service2`) exist.
When it has done so, you can see the address of the load balancer at the
Address field.
{{< note >}}
Depending on the [Ingress controller](/docs/concepts/services-networking/ingress-controllers/)
you are using, you may need to create a default-http-backend
[Service](/docs/concepts/services-networking/service/).
{{< /note >}}
### Name based virtual hosting
Name-based virtual hosts support routing HTTP traffic to multiple host names at the same IP address.
{{< mermaid >}}
graph LR;
client([client])-. Ingress-managed <br> load balancer .->ingress[Ingress, 178.91.123.132];
ingress-->|Host: foo.bar.com|service1[Service service1:80];
ingress-->|Host: bar.foo.com|service2[Service service2:80];
subgraph cluster
ingress;
service1-->pod1[Pod];
service1-->pod2[Pod];
service2-->pod3[Pod];
service2-->pod4[Pod];
end
classDef plain fill:#ddd,stroke:#fff,stroke-width:4px,color:#000;
classDef k8s fill:#326ce5,stroke:#fff,stroke-width:4px,color:#fff;
classDef cluster fill:#fff,stroke:#bbb,stroke-width:2px,color:#326ce5;
class ingress,service1,service2,pod1,pod2,pod3,pod4 k8s;
class client plain;
class cluster cluster;
{{</ mermaid >}}
The following Ingress tells the backing load balancer to route requests based on
the [Host header](https://tools.ietf.org/html/rfc7230#section-5.4).
{{< codenew file="service/networking/name-virtual-host-ingress.yaml" >}}
If you create an Ingress resource without any hosts defined in the rules, then any
web traffic to the IP address of your Ingress controller can be matched without a name based
virtual host being required.
For example, the following Ingress routes traffic
requested for `first.bar.com` to `service1`, `second.bar.com` to `service2`, and any traffic
to the IP address without a hostname defined in request (that is, without a request header being
presented) to `service3`.
{{< codenew file="service/networking/name-virtual-host-ingress-no-third-host.yaml" >}}
### TLS
You can secure an Ingress by specifying a {{< glossary_tooltip term_id="secret" >}}
that contains a TLS private key and certificate. The Ingress resource only
supports a single TLS port, 443, and assumes TLS termination at the ingress point
(traffic to the Service and its Pods is in plaintext).
If the TLS configuration section in an Ingress specifies different hosts, they are
multiplexed on the same port according to the hostname specified through the
SNI TLS extension (provided the Ingress controller supports SNI). The TLS secret
must contain keys named `tls.crt` and `tls.key` that contain the certificate
and private key to use for TLS. For example:
```yaml
apiVersion: v1
kind: Secret
metadata:
name: testsecret-tls
namespace: default
data:
tls.crt: base64 encoded cert
tls.key: base64 encoded key
type: kubernetes.io/tls
```
Referencing this secret in an Ingress tells the Ingress controller to
secure the channel from the client to the load balancer using TLS. You need to make
sure the TLS secret you created came from a certificate that contains a Common
Name (CN), also known as a Fully Qualified Domain Name (FQDN) for `https-example.foo.com`.
{{< note >}}
Keep in mind that TLS will not work on the default rule because the
certificates would have to be issued for all the possible sub-domains. Therefore,
`hosts` in the `tls` section need to explicitly match the `host` in the `rules`
section.
{{< /note >}}
{{< codenew file="service/networking/tls-example-ingress.yaml" >}}
{{< note >}}
There is a gap between TLS features supported by various Ingress
controllers. Please refer to documentation on
[nginx](https://kubernetes.github.io/ingress-nginx/user-guide/tls/),
[GCE](https://git.k8s.io/ingress-gce/README.md#frontend-https), or any other
platform specific Ingress controller to understand how TLS works in your environment.
{{< /note >}}
### Load balancing {#load-balancing}
An Ingress controller is bootstrapped with some load balancing policy settings
that it applies to all Ingress, such as the load balancing algorithm, backend
weight scheme, and others. More advanced load balancing concepts
(e.g. persistent sessions, dynamic weights) are not yet exposed through the
Ingress. You can instead get these features through the load balancer used for
a Service.
It's also worth noting that even though health checks are not exposed directly
through the Ingress, there exist parallel concepts in Kubernetes such as
[readiness probes](/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/)
that allow you to achieve the same end result. Please review the controller
specific documentation to see how they handle health checks (for example:
[nginx](https://git.k8s.io/ingress-nginx/README.md), or
[GCE](https://git.k8s.io/ingress-gce/README.md#health-checks)).
## Updating an Ingress
To update an existing Ingress to add a new Host, you can update it by editing the resource:
```shell
kubectl describe ingress test
```
```
Name: test
Namespace: default
Address: 178.91.123.132
Default backend: default-http-backend:80 (10.8.2.3:8080)
Rules:
Host Path Backends
---- ---- --------
foo.bar.com
/foo service1:80 (10.8.0.90:80)
Annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ADD 35s loadbalancer-controller default/test
```
```shell
kubectl edit ingress test
```
This pops up an editor with the existing configuration in YAML format.
Modify it to include the new Host:
```yaml
spec:
rules:
- host: foo.bar.com
http:
paths:
- backend:
service:
name: service1
port:
number: 80
path: /foo
pathType: Prefix
- host: bar.baz.com
http:
paths:
- backend:
service:
name: service2
port:
number: 80
path: /foo
pathType: Prefix
..
```
After you save your changes, kubectl updates the resource in the API server, which tells the
Ingress controller to reconfigure the load balancer.
Verify this:
```shell
kubectl describe ingress test
```
```
Name: test
Namespace: default
Address: 178.91.123.132
Default backend: default-http-backend:80 (10.8.2.3:8080)
Rules:
Host Path Backends
---- ---- --------
foo.bar.com
/foo service1:80 (10.8.0.90:80)
bar.baz.com
/foo service2:80 (10.8.0.91:80)
Annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ADD 45s loadbalancer-controller default/test
```
You can achieve the same outcome by invoking `kubectl replace -f` on a modified Ingress YAML file.
## Failing across availability zones
Techniques for spreading traffic across failure domains differ between cloud providers.
Please check the documentation of the relevant [Ingress controller](/docs/concepts/services-networking/ingress-controllers) for details.
## Alternatives
You can expose a Service in multiple ways that don't directly involve the Ingress resource:
* Use [Service.Type=LoadBalancer](/docs/concepts/services-networking/service/#loadbalancer)
* Use [Service.Type=NodePort](/docs/concepts/services-networking/service/#nodeport)
## {{% heading "whatsnext" %}}
* Learn about the [Ingress API](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#ingress-v1beta1-networking-k8s-io)
* Learn about [Ingress controllers](/docs/concepts/services-networking/ingress-controllers/)
* [Set up Ingress on Minikube with the NGINX Controller](/docs/tasks/access-application-cluster/ingress-minikube/)
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