External Service

This policy allows services running inside the mesh to consume services that are not part of the mesh. The ExternalService resource allows you to declare specific external resources by name within the mesh, instead of implementing the default passthrough mode. Passthrough mode allows access to any non-mesh host by specifying its domain name or IP address, without the ability to apply any traffic policies. The ExternalService resource enables the same observability, security, and traffic manipulation for external traffic as for services entirely inside the mesh

When you enable this policy, you should also disable passthrough mode for the mesh and enable the data plane proxy builtin DNS name resolution.

Usage

A simple HTTPS external service can be defined:

  1. apiVersion: kuma.io/v1alpha1
  2. kind: ExternalService
  3. mesh: default
  4. metadata:
  5.   namespace: default
  6.   name: httpbin
  7. spec:
  8.   tags:
  9.     kuma.io/service: httpbin
  10.     kuma.io/protocol: http
  11.   networking:
  12.     address: httpbin.org:443
  13.     tls:
  14.       enabled: true

Then apply the configuration with kubectl apply -f [..].

  1. type: ExternalService
  2. mesh: default
  3. name: httpbin
  4. tags:
  5.   kuma.io/service: httpbin
  6.   kuma.io/protocol: http
  7. networking:
  8.   address: httpbin.org:443
  9.   tls:
  10.     enabled: true

Then apply the configuration with kumactl apply -f [..] or with the HTTP API.

Universal mode is best combined with transparent proxy. For backward compatibility only, you can consume an external service from within the mesh by filling the proper outbound section of the relevant data plane resource:

  1. type: Dataplane
  2. mesh: default
  3. name: redis-dp
  4. networking:
  5.   address: 127.0.0.1
  6.   inbound:
  7.   - port: 9000
  8.     tags:
  9.       kuma.io/service: redis
  10.   outbound:
  11.   - port: 10000
  12.     tags:
  13.       kuma.io/service: httpbin

Then httpbin.org is accessible at 127.0.0.1:10000.

Accessing the External Service

Consuming the defined service from within the mesh for both Kubernetes and Universal deployments (assuming transparent proxy) can be done:

  • With the .mesh naming of the service curl httpbin.mesh. With this approach, specify port 80.
  • With the real name and port, in this case curl httpbin.org:443. This approach works only with the data plane proxy builtin DNS name resolution.

Although the external service is HTTPS, it’s consumed as plain HTTP. This is possible because of networking.tls.enbaled=true. To access the service over TLS, set the service protocol to kuma.io/protocol: tcp and networking.tls.enbaled=false, or else omit it entirely.

Available policy fields

  • tags the external service can include an arbitrary number of tags, where kuma.io/service is mandatory. The special kuma.io/protocol tag is also taken into account and supports the standard Kuma protocol values. It designates the specific protocol for the service.
  • networking describes the networking configuration of the external service
    • address is the address where the external service can be reached.
    • tls is the section to configure the TLS originator when consuming the external service
      • enabled turns on and off the TLS origination. Defaults to true
      • caCert the CA certificate for the external service TLS verification
      • clientCert the client certificate for mTLS
      • clientKey the client key for mTLS

As with other services, avoid duplicating service names under kuma.io/service with already existing ones. A good practice is to derive the tag value from the domain name or IP of the actual external service.