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214 lines
6.1 KiB
Markdown
214 lines
6.1 KiB
Markdown
# Configuring ExternalDNS to use the OpenShift Route Source
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This tutorial describes how to configure ExternalDNS to use the OpenShift Route source.
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It is meant to supplement the other provider-specific setup tutorials.
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### For OCP 4.x
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In OCP 4.x, if you have multiple [OpenShift ingress controllers](https://docs.openshift.com/container-platform/4.9/networking/ingress-operator.html) then you must specify an ingress controller name (also called router name), you can get it from the route's `status.ingress[*].routerName` field.
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If you don't specify a router name when you have multiple ingress controllers in your cluster then the first router from the route's `status.ingress` will be used. Note that the router must have admitted the route in order to be selected.
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Once the router is known, ExternalDNS will use this router's canonical hostname as the target for the CNAME record.
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Starting from OCP 4.10 you can use [ExternalDNS Operator](https://github.com/openshift/external-dns-operator) to manage ExternalDNS instances. Example of its custom resource for AWS provider:
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```yaml
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apiVersion: externaldns.olm.openshift.io/v1alpha1
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kind: ExternalDNS
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metadata:
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name: sample
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spec:
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provider:
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type: AWS
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source:
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openshiftRouteOptions:
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routerName: default
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type: OpenShiftRoute
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zones:
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- Z05387772BD5723IZFRX3
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```
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This will create an ExternalDNS POD with the following container args in `external-dns` namespace:
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```
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spec:
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containers:
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- args:
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- --metrics-address=127.0.0.1:7979
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- --txt-owner-id=external-dns-sample
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- --provider=aws
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- --source=openshift-route
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- --policy=sync
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- --registry=txt
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- --log-level=debug
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- --zone-id-filter=Z05387772BD5723IZFRX3
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- --openshift-router-name=default
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- --txt-prefix=external-dns-
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```
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### For OCP 3.11 environment
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### Prepare ROUTER_CANONICAL_HOSTNAME in default/router deployment
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Read and go through [Finding the Host Name of the Router](https://docs.openshift.com/container-platform/3.11/install_config/router/default_haproxy_router.html#finding-router-hostname).
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If no ROUTER_CANONICAL_HOSTNAME is set, you must annotate each route with external-dns.alpha.kubernetes.io/target!
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### Manifest (for clusters without RBAC enabled)
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: external-dns
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spec:
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strategy:
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type: Recreate
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selector:
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matchLabels:
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app: external-dns
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template:
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metadata:
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labels:
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app: external-dns
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spec:
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containers:
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- name: external-dns
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image: registry.k8s.io/external-dns/external-dns:v0.14.0
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args:
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- --source=openshift-route
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- --domain-filter=external-dns-test.my-org.com # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
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- --provider=aws
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- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
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- --aws-zone-type=public # only look at public hosted zones (valid values are public, private or no value for both)
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- --registry=txt
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- --txt-owner-id=my-identifier
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```
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### Manifest (for clusters with RBAC enabled)
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```yaml
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: external-dns
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---
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apiVersion: rbac.authorization.k8s.io/v1
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kind: ClusterRole
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metadata:
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name: external-dns
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rules:
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- apiGroups: [""]
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resources: ["services","endpoints","pods"]
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verbs: ["get","watch","list"]
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- apiGroups: ["extensions","networking.k8s.io"]
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resources: ["ingresses"]
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verbs: ["get","watch","list"]
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- apiGroups: [""]
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resources: ["nodes"]
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verbs: ["list"]
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- apiGroups: ["route.openshift.io"]
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resources: ["routes"]
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verbs: ["get","watch","list"]
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---
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apiVersion: rbac.authorization.k8s.io/v1
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kind: ClusterRoleBinding
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metadata:
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name: external-dns-viewer
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roleRef:
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apiGroup: rbac.authorization.k8s.io
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kind: ClusterRole
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name: external-dns
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subjects:
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- kind: ServiceAccount
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name: external-dns
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namespace: default
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---
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: external-dns
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spec:
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strategy:
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type: Recreate
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selector:
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matchLabels:
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app: external-dns
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template:
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metadata:
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labels:
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app: external-dns
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spec:
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serviceAccountName: external-dns
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containers:
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- name: external-dns
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image: registry.k8s.io/external-dns/external-dns:v0.14.0
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args:
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- --source=openshift-route
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- --domain-filter=external-dns-test.my-org.com # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
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- --provider=aws
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- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
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- --aws-zone-type=public # only look at public hosted zones (valid values are public, private or no value for both)
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- --registry=txt
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- --txt-owner-id=my-identifier
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```
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### Verify External DNS works (OpenShift Route example)
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The following instructions are based on the
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[Hello Openshift](https://github.com/openshift/origin/tree/HEAD/examples/hello-openshift).
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#### Install a sample service and expose it
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```bash
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$ oc apply -f - <<EOF
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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labels:
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app: hello-openshift
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name: hello-openshift
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spec:
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replicas: 1
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selector:
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matchLabels:
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app: hello-openshift
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template:
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metadata:
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labels:
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app: hello-openshift
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spec:
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containers:
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- image: openshift/hello-openshift
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name: hello-openshift
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---
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apiVersion: v1
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kind: Service
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metadata:
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labels:
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app: hello-openshift
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name: hello-openshift
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spec:
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ports:
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- port: 8080
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protocol: TCP
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targetPort: 8080
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selector:
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app: hello-openshift
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sessionAffinity: None
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type: ClusterIP
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---
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apiVersion: route.openshift.io/v1
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kind: Route
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metadata:
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name: hello-openshift
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spec:
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host: hello-openshift.example.com
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to:
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kind: Service
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name: hello-openshift
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weight: 100
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wildcardPolicy: None
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EOF
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```
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#### Access the sample route using `curl`
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```bash
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$ curl -i http://hello-openshift.example.com
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HTTP/1.1 200 OK
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Date: Fri, 10 Apr 2020 09:36:41 GMT
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Content-Length: 17
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Content-Type: text/plain; charset=utf-8
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Hello OpenShift!
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```
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