OpenShift Container Platform provides methods for communicating from outside the cluster with services running in the cluster. This method uses a NodePort.

Using a NodePort to get traffic into the cluster

Use a NodePort-type Service resource to expose a service on a specific port on all nodes in the cluster. The port is specified in the Service resource’s .spec.ports[*].nodePort field.

Using NodePorts requires additional port resources.

A NodePort exposes the service on a static port on the node IP address. NodePorts are in the 30000 to 32767 range by default, which means a NodePort is unlikely to match a service’s intended port. For example, 8080 may be exposed as 31020.

The administrator must ensure the external IPs are routed to the nodes.

NodePorts and external IPs are independent and both can be used concurrently.

The procedures in this section require prerequisites performed by the cluster administrator.

Prerequisites

Before starting the following procedures, the administrator must:

  • Set up the external port to the cluster networking environment so that requests can reach the cluster.

  • Make sure there is at least one user with cluster admin role. To add this role to a user, run the following command:

    $ oc adm policy add-cluster-role-to-user cluster-admin <user_name>
  • Have an OpenShift Container Platform cluster with at least one master and at least one node and a system outside the cluster that has network access to the cluster. This procedure assumes that the external system is on the same subnet as the cluster. The additional networking required for external systems on a different subnet is out-of-scope for this topic.

Creating a project and service

If the project and service that you want to expose do not exist, first create the project, then the service.

If the project and service already exist, skip to the procedure on exposing the service to create a route.

Procedure
  1. Log in to OpenShift Container Platform.

  2. Create a new project for your service:

    $ oc new-project <project_name>

    For example:

    $ oc new-project myproject
  3. Use the oc new-app command to create a service. For example:

    $ oc new-app \
        -e MYSQL_USER=admin \
        -e MYSQL_PASSWORD=redhat \
        -e MYSQL_DATABASE=mysqldb \
        registry.redhat.io/openshift3/mysql-55-rhel7
  4. Run the following command to see that the new service is created:

    $ oc get svc -n openshift-ingress
    NAME                      TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)                      AGE
    router-default            LoadBalancer   172.30.16.119   52.230.228.163   80:30745/TCP,443:32561/TCP   2d6h
    router-internal-default   ClusterIP      172.30.101.15   <none>           80/TCP,443/TCP,1936/TCP      2d6h

    By default, the new service does not have an external IP address.

Exposing the service by creating a route

You can expose the service as a route using the oc expose command.

Procedure

To expose the service:

  1. Log in to OpenShift Container Platform.

  2. Log in to the project where the service you want to expose is located:

    $ oc project project1
  3. Run the following command to expose the route:

    $ oc expose service <service_name>

    For example:

    $ oc expose service mysql-55-rhel7
    route "mysql-55-rhel7" exposed
  4. Use a tool, such as cURL, to make sure you can reach the service using the cluster IP address for the service:

    $ curl <pod_ip>:<port>

    For example:

    $ curl 172.30.131.89:3306

    The examples in this section use a MySQL service, which requires a client application. If you get a string of characters with the Got packets out of order message, you are connected to the service.

    If you have a MySQL client, log in with the standard CLI command:

    $ mysql -h 172.30.131.89 -u admin -p
    Enter password:
    Welcome to the MariaDB monitor.  Commands end with ; or \g.
    
    MySQL [(none)]>