How to parameterize ports in OpenShift JSON Project Template - openshift-origin

Question

I'm trying to create a custom project template in OpenShift Origin. The Service configuration specifically, looks like below:
{
"kind": "Service",
"apiVersion": "v1",
"metadata": {
"name": "${NAME}",
"annotations": {
"description": "Exposes and load balances the node.js application pods"
}
},
"spec": {
"ports": [
{
"name": "web",
"port": "${APPLICATION_PORT}",
"targetPort": "${APPLICATION_PORT}",
"protocol": "TCP"
}
],
"selector": {
"name": "${NAME}"
}
}
},
where, APPLICATION_PORT is supplied as a user parameter:
"parameters": [
{
"name": "APPLICATION_PORT",
"displayName": "Application Port",
"description": "The exposed port that will route to the node.js application",
"value": "8000"
},
When I try to use this template to create a project, I get the following error:
spec.ports[0].targetPort: Invalid value: "8000": must be an IANA_SVC_NAME (at most 15 characters, matching regex [a-z0-9]([a-z0-9-]*[a-z0-9])*...
I get a similar error in my DeploymentConfig as well, for the http ports in the liveness and readiness probes:
"readinessProbe": {
"timeoutSeconds": 3,
"initialDelaySeconds": 3,
"httpGet": {
"path": "/Info",
"port": "${APPLICATION_ADMIN_PORT}"
}
},
"livenessProbe": {
"timeoutSeconds": 3,
"initialDelaySeconds": 30,
"httpGet": {
"path": "/Info",
"port": "${APPLICATION_ADMIN_PORT}"
}
},
where, APPLICATION_ADMIN_PORT, again, is user-supplied.
Error:
spec.template.spec.containers[0].livenessProbe.httpGet.port: Invalid value: "8001": must be an IANA_SVC_NAME...
spec.template.spec.containers[0].readinessProbe.httpGet.port: Invalid value: "8001": must be an IANA_SVC_NAME...
I've been following https://blog.openshift.com/part-2-creating-a-template-a-technical-walkthrough/ to understand templates, and it, unfortunately, does not have any examples of ports being parameterized anywhere.
It almost seems as if strings are not allowed as the values of these ports. Is that the case? What's the right way to parameterize these values? Should I switch to YAML?
Versions:
OpenShift Master: v1.1.6-3-g9c5694f
Kubernetes Master: v1.2.0-36-g4a3f9c5
Edit 1: I tried the same configuration in YAML format, and got the same error. So, JSON vs YAML is not the issue.

Answer 1

Unfortunately it is not currently possible to parameterize non-string field values: https://docs.openshift.org/latest/dev_guide/templates.html#writing-parameters
" Parameters can be referenced by placing values in the form "${PARAMETER_NAME}" in place of any string field in the template."
Templates are in the process of being upstreamed to Kubernetes and this limitation is being addressed there:
https://github.com/kubernetes/kubernetes/blob/master/docs/proposals/templates.md
The proposal is being implemented in PRs 25622 and 25293 in the kubernetes repo.
edit:
Templates now support non-string parameters as documented here: https://docs.openshift.org/latest/dev_guide/templates.html#writing-parameters

Answer 2

I don't know if this option was available in 2016 when this post was added but now you can use ${{PARAMETER_NAME}} to parameterize non-string field values.
spec:
externalTrafficPolicy: Cluster
ports:
- name: ${NAME}-port
port: ${{PORT_PARAMETER}}
protocol: TCP
targetPort: ${{PORT_PARAMETER}}
sessionAffinity: None

Answer 3

This may a be a bad practice but I'm using sed to substitute int parameters:
cat template.yaml | sed -e 's/PORT/8080/g' > proxy-template-subst.yaml
Template:
apiVersion: template.openshift.io/v1
kind: Template
objects:
- apiVersion: v1
kind: Service
metadata:
name: ${NAME}
namespace: ${NAMESPACE}
spec:
externalTrafficPolicy: Cluster
ports:
- name: ${NAME}-port
port: PORT
protocol: TCP
targetPort: PORT
sessionAffinity: None
type: NodePort
status:
loadBalancer: {}
parameters:
- description: Desired service name
name: NAME
required: true
value: need_real_value_here
- description: IP adress
name: IP
required: true
value: need_real_value_here
- description: namespace where to deploy
name: NAMESPACE
required: true
value: need_real_value_here