External APIs

Traefik Hub API Management allows you to manage and expose APIs not only within your Kubernetes cluster but also external services residing outside of it. This is particularly useful when you need to expose legacy systems or third-party APIs.

Enabling ExternalName Services in Traefik Hub

To allow Traefik Hub to interact with external services, you need to enable specific parameters in your deployment.

Update Traefik Deployment

First, you need to add the following arguments to your Traefik deployment configuration:

CLI

- --providers.kubernetescrd.allowExternalNameServices=true

Chart

values.yaml

providers:
  kubernetesCRD:
    allowExternalNameServices: true

These arguments enable Traefik Hub to:

• allowexternalnameservices: Use ExternalName services, which point to external DNS names.

After including this, you can now upgrade your deployment with the updated values.yaml file:

helm upgrade traefik traefik/traefik -n traefik -f values.yaml

Note

You can also include - --providers.kubernetescrd.allowCrossNamespace=true in your Helm values to enable referencing services across different namespaces.

If this feature has been enabled in your deployment sucessfully, you should see the following when you inspect the Traefik pod:

Configuring External API Access

With Traefik Hub configured to allow external services, you can now set up the necessary Kubernetes resources.

Create an ExternalName Service

Define a Service of type ExternalName that maps to the external API DNS name.

Example

world-time-api.yaml

apiVersion: v1
kind: Service
metadata:
  name: world-time-api
  namespace: traefik
spec:
  type: ExternalName
  externalName: worldtimeapi.org
  ports:
    - port: 443

Field	Description
type	Indicates that the service maps to a DNS name.
externalName	The external API DNS name.
ports	The port on which the external service listens.

Apply the resource:

kubectl apply -f world-time-api.yaml

Define the API Resource

Create an API resource to represent the external API within Traefik Hub.

Example

time-api.yaml

apiVersion: hub.traefik.io/v1alpha1
kind: API
metadata:
  name: time-api
  namespace: traefik
spec:
  openApiSpec:
    url: https://worldtimeapi.org/api

Field	Description
openApiSpec.url	The URL to the API's OpenAPI specification.

Apply the resource:

kubectl apply -f time-api.yaml

Set Up API Access

Configure an APIAccess resource to define who can access the API.

Example

time-api-access.yaml

apiVersion: hub.traefik.io/v1alpha1
kind: APIAccess
metadata:
  name: time-api
  namespace: traefik
spec:
  apis:
    - name: time-api
  everyone: true

Field	Description
everyone : true	Allows every authenticated user to access the API.

Apply the resource:

kubectl apply -f time-api-access.yaml

Create an IngressRoute

Define an IngressRoute to route incoming traffic to the external service.

Example

time-api-ingressroute.yaml

apiVersion: traefik.io/v1alpha1
kind: IngressRoute
metadata:
  name: time-api
  namespace: traefik
  annotations:
    hub.traefik.io/api: time-api
spec:
  entryPoints:
    - websecure
  routes:
    - match: Host(`api.yourdomain.com`) && PathPrefix(`/time`)
      kind: Rule
      services:
        - name: world-time-api
          port: 443

Field	Description
annotations.hub.traefik.io/api	Associates the route with the API resource
match	Defines routing rules based on host and path.
services.name	References the ExternalName service

Apply the resource:

kubectl apply -f time-api-ingressroute.yaml

With the above example, you should be able to replicate a working set up with the External API service feature.

Notes

• Ensure that your DNS records point to Traefik's ingress controller.
• Verify that the external API you want to make use of is accessible from your Kubernetes cluster.
• When using websecure, make sure TLS is properly configured.

Securing External APIs with mTLS

To enhance security when connecting to external APIs, you can configure mutual TLS (mTLS) between Traefik and the external service. This ensures that both parties authenticate each other before establishing a connection.

Before you can make use of mTLS with your external APIs, you need to do the following:

Create a Secret for Client CA Certificate

First, you need to create a Kubernetes Secret containing the CA certificate used to verify client certificates.

Example

kubectl create secret generic client-ca-cert \
  --from-file=ca.crt \
  -n traefik

Field	Description
ca.crt	Certificate Authority certificate used to verify the server's certificate.

Create a TLSOption Resource with clientAuth

To require client certificates when clients connect to Traefik, define a TLSOption resource with clientAuth.

Example

tls-option.yaml

apiVersion: traefik.containo.us/v1alpha1
kind: TLSOption
metadata:
  name: mtls
  namespace: traefik
spec:
  clientAuth:
    clientAuthType: RequireAndVerifyClientCert
    secretNames:
      - client-ca-cert

Field	Description
clientAuthType	Specifies the client authentication type.
clientAuthType: RequireAndVerifyClientCert	enforces mTLS, requiring clients to present valid certificates.
secretNames	List of secrets containing CA certificates to verify client certificates.

Apply the TLSOption resource:

kubectl apply -f tls-option.yaml

Define a ServersTransport Resource

Create a ServersTransport resource to specify TLS settings for communication with the external service.

Example

serverstransport.yaml

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: world-time-api-transport
  namespace: traefik
spec:
  serverName: worldtimeapi.org
  insecureSkipVerify: false
  rootCAsSecrets:
    - world-time-api-cert
  certificatesSecrets:
    - world-time-api-cert

Field	Description
serverName	Expected server name in the server's certificate.
insecureSkipVerify	Client certificate presented to the server.
rootCAsSecrets	References secrets containing CA certificates to verify the server.
certificatesSecrets	References secrets containing client certificates for mTLS.

Apply the ServersTransport resource:

kubectl apply -f serverstransport.yaml

Update the IngressRoute to Use ServersTransport and TLS

Modify your IngressRoute to reference the ServersTransport and TLSOption resource.

Example

apiVersion: traefik.io/v1alpha1
kind: IngressRoute
metadata:
  name: time-api
  namespace: traefik
  annotations:
    hub.traefik.io/api: time-api
spec:
  entryPoints:
    - websecure
  routes:
    - match: Host(`api.yourdomain.com`) && PathPrefix(`/time`)
      kind: Rule
      services:
        - name: world-time-api
          port: 443
          scheme: https
          serversTransport: world-time-api-transport@kubernetescrd
  tls:
    options:
      name: mtls
      namespace: traefik

Apply the updated IngressRoute:

kubectl apply -f time-api-ingressroute.yaml

Testing the mTLS Configuration

To test mTLS between clients and Traefik, use a client certificate signed by the CA specified in client-ca-cert.

curl --cert client.crt --key client.key https://api.yourdomain.com/time

You should receive a response from the external API, confirming that client mTLS is correctly configured.

Note

• Ensure that the external API supports mTLS and that the certificates are valid.
• Replace client.crt and client.key with your client certificate and key files.
• Ensure the client certificate is signed by the CA in client-ca-cert.

Troubleshooting

Error: ExternalName Services Not Allowed

If you encounter the following error:

ERR error="externalName services not allowed: traefik/world-time-api"

This indicates that the allowexternalnameservices parameter is not enabled in Traefik's configuration. Ensure you've added --providers.kubernetescrd.allowexternalnameservices=true to your Traefik deployment arguments.

Related Content

• Learn more about the API object in its dedicated section.
• Learn more about APIAcess in its dedication section.
• Learn more about TLSOption in its dedicated section
• Learn more about ServersTransport in its dedicated documentation.