Generate manifests for CoreDNS pod definition and Corefile template

For cloud platforms where customers are allowed to bring their own
DNS post cluster install, an in-cluster DNS solution is required
for the installation to be successful.
Adding the manifest containing CoreDNS pod definition and Corefile
template to be used by the MCO instance on the bootstrap node.

manifests/cloud-platform-alt-dns/coredns-corefile.tmpl

@@ -0,0 +1,24 @@
+. {
+    errors
+    health :18080
+    cache 30
+    reload
+    template IN {{`{{ .Cluster.CloudLBRecordType }}`}} {{ .ControllerConfig.DNS.Spec.BaseDomain }} {
+        match ^api.{{ .ControllerConfig.DNS.Spec.BaseDomain }}
+        answer "{{`{{"{{ .Name }}"}}`}} 60 in {{`{{"{{ .Type }}"}}`}} {{ if gt (len (.Cluster.APILBIPs )) 0 }}{{ index (.Cluster.APILBIPs) 0 }}{{ end }}"
+        fallthrough
+    }
+    template IN {{`{{ .Cluster.CloudLBEmptyType }}`}} {{ .ControllerConfig.DNS.Spec.BaseDomain }} {
+        match ^api.{{ .ControllerConfig.DNS.Spec.BaseDomain }}
+        fallthrough
+    }
+    template IN {{`{{ .Cluster.CloudLBRecordType }}`}} {{ .ControllerConfig.DNS.Spec.BaseDomain }} {
+        match ^api-int.{{ .ControllerConfig.DNS.Spec.BaseDomain }}
+        answer "{{`{{"{{ .Name }}"}}`}} 60 in {{`{{"{{ .Type }}"}}`}} {{ if gt (len (.Cluster.APIIntLBIPs)) 0 }}{{ index (.Cluster.APIIntLBIPs) 0 }}{{ end }}"
+        fallthrough
+    }
+    template IN {{`{{ .Cluster.CloudLBEmptyType }}`}} {{ .ControllerConfig.DNS.Spec.BaseDomain }} {
+        match ^api-int.{{ .ControllerConfig.DNS.Spec.BaseDomain }}
+        fallthrough
+    }
+}

manifests/cloud-platform-alt-dns/coredns.yaml

@@ -0,0 +1,83 @@
+---
+kind: Pod
+apiVersion: v1
+metadata:
+  name: coredns
+  namespace: openshift-infra
+  creationTimestamp:
+  deletionGracePeriodSeconds: 65
+  labels:
+    app: {{ cloudPlatformShortName .ControllerConfig }}-infra-coredns
+  annotations:
+    target.workload.openshift.io/management: '{"effect": "PreferredDuringScheduling"}'
+spec:
+  volumes:
+  - name: resource-dir
+    hostPath:
+      path: "/etc/kubernetes/static-pod-resources/coredns"
+  - name: kubeconfig
+    hostPath:
+      path: "/etc/kubernetes/kubeconfig"
+  - name: conf-dir
+    empty-dir: {}
+  - name: manifests
+    hostPath:
+      path: "/opt/openshift/manifests"
+  initContainers:
+  - name: render-config
+    image: {{ .Images.BaremetalRuntimeCfgBootstrap }}
+    command:
+    - runtimecfg
+    - render
+    - "/etc/kubernetes/kubeconfig"
+    - "--cloud-ext-lb-ips"
+    - "{{- range $index, $ips := .CloudExtLBIPs }}{{ if gt $index 0 }},{{end}}{{$ip}}{{end}}"
+    - "--cloud-int-lb-ips"
+    - "{{- range $index, $ips := .CloudIntLBIPs }}{{ if gt $index 0 }},{{end}}{{$ip}}{{end}}"
+    - "/config"
+    - "--out-dir"
+    - "/etc/coredns"
+    - "--cluster-config"
+    - "/opt/openshift/manifests/cluster-config.yaml"
+  resources: {}
+  volumeMounts:
+  - name: kubeconfig
+    mountpath: "/etc/kubernetes/kubeconfig"
+  - name: resource-dir
+    mountpath: "/config"
+  - name: conf-dir
+    mountpath: "/etc/coredns"
+  - name: manifests
+    mountpath: "/opt/openshift/manifests"
+    imagePullPolicy: IfNotPresent
+  containers:
+  - name: coredns
+    securityContext:
+      privileged: true
+      readOnlyRootFilesystem: false
+    image: {{ .Images.CorednsBootstrap }}
+    args:
+    - "--conf"
+    - "/etc/coredns/Corefile"
+    resources:
+      requests:
+        cpu: 100m
+        memory: 200Mi
+    volumeMounts:
+    - name: conf-dir
+      mountPath: "/etc/coredns"
+    livenessProbe:
+      httpGet:
+        path: /health
+        port: 18080
+        scheme: HTTP
+      initialDelaySeconds: 60
+      timeoutSeconds: 5
+      successThreshold: 1
+      failureThreshold: 5
+    terminationMessagePolicy: FallbackToLogsOnError
+  hostNetwork: true
+  tolerations:
+  - operator: Exists
+  priorityClassName: system-node-critical
+status: {}