Chapter 18. Integrating External Services

You can define a service either by providing an IP address and endpoints, or by providing a Fully qualified domain name (FQDN).

kind: "Service"
apiVersion: "v1"
metadata:
  name: "external-mysql-service"
spec:
  type: ExternalName
  externalName: example.domain.name
selector: {} 1

Now that the service and endpoints are defined, give the appropriate pods access to the credentials to use the service by setting environment variables in the appropriate containers:

kind: "DeploymentConfig"
apiVersion: "v1"
metadata:
  name: "my-app-deployment"
spec: 1
  strategy:
    type: "Rolling"
    rollingParams:
      updatePeriodSeconds: 1 2
      intervalSeconds: 1 3
      timeoutSeconds: 120
  replicas: 2
  selector:
    name: "frontend"
  template:
    metadata:
      labels:
        name: "frontend"
    spec:
      containers:
        -
          name: "helloworld"
          image: "origin-ruby-sample"
          ports:
            -
              containerPort: 3306
              protocol: "TCP"
          env:
            -
              name: "MYSQL_USER"
              value: "${MYSQL_USER}" 4
            -
              name: "MYSQL_PASSWORD"
              value: "${MYSQL_PASSWORD}" 5
            -
              name: "MYSQL_DATABASE"
              value: "${MYSQL_DATABASE}" 6

External Database Environment Variables

Using an external service in your application is similar to using an internal service. Your application will be assigned environment variables for the service and the additional environment variables with the credentials described in the previous step. For example, a MySQL container receives the following environment variables:

The application is responsible for reading the coordinates and credentials for the service from the environment and establishing a connection with the database via the service.

External SaaS Provider Environment Variables

Similarly, when using an internal service, your application is assigned environment variables for the service and the additional environment variables with the credentials described in the previous steps. In the previous example, the container receives the following environment variables:

The application reads the coordinates and credentials for the service from the environment and establishes a connection with the service.

ExternalName services do not have selectors, or any defined ports or endpoints. You can use an ExternalName service to assign traffic to an external service outside the cluster.

  kind: "Service"
  apiVersion: "v1"
  metadata:
    name: "external-mysql-service"
  spec:
    type: ExternalName
    externalName: example.domain.name
  selector: {} 1

Using an ExternalName service maps the service to the value of the externalName field (example.domain.name in the previous example), by automatically injecting a CNAME record, mapping the service name directly to an outside DNS address, and bypassing the need for endpoint records.