15.6. Configuring ingress cluster traffic using a NodePort
OpenShift Container Platform provides methods for communicating from outside the cluster with services running in the cluster. This method uses a NodePort.
15.6.1. 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 a node port requires additional port resources.
A NodePort exposes the service on a static port on the node’s 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, port 8080 may be exposed as port 31020 on the node.
The administrator must ensure the external IP addresses 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.
15.6.2. 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.
15.6.3. 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.
Prerequisites
-
Install the
ocCLI and log in as a cluster administrator.
Procedure
Create a new project for your service:
$ oc new-project <project_name>
For example:
$ oc new-project myproject
Use the
oc new-appcommand to create a service. For example:$ oc new-app \ -e MYSQL_USER=admin \ -e MYSQL_PASSWORD=redhat \ -e MYSQL_DATABASE=mysqldb \ registry.redhat.io/rhscl/mysql-80-rhel7Run the following command to see that the new service is created:
$ oc get svc -n myproject
Example output
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE mysql-80-rhel7 ClusterIP 172.30.63.31 <none> 3306/TCP 4m55s
By default, the new service does not have an external IP address.
15.6.4. Exposing the service by creating a route
You can expose the service as a route by using the oc expose command.
Procedure
To expose the service:
- Log in to OpenShift Container Platform.
Log in to the project where the service you want to expose is located:
$ oc project myproject
To expose a node port for the application, enter the following command. OpenShift Container Platform automatically selects an available port in the
30000-32767range.$ oc expose dc mysql-80-rhel7 --type=NodePort --name=mysql-ingress
Optional: To confirm the service is available with a node port exposed, enter the following command:
$ oc get svc -n myproject
Example output
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE mysql-80-rhel7 ClusterIP 172.30.217.127 <none> 3306/TCP 9m44s mysql-ingress NodePort 172.30.107.72 <none> 3306:31345/TCP 39s
Optional: To remove the service created automatically by the
oc new-appcommand, enter the following command:$ oc delete svc mysql-80-rhel7
