From aadbd9f671fbcff41ce55f59cab154413a59a93c Mon Sep 17 00:00:00 2001
From: Sandhya Dasu <sdasu@redhat.com>
Date: Wed, 22 Jan 2025 12:05:35 -0500
Subject: [PATCH] GCP: Update /etc/hosts file when ClusterHostedDNS is enable

Append /etc/hosts files with entries to resolve cluster api and
api-int URLS. /etc/hosts will provide resolution for these URLs
until kubelet joins the cluster and runs its CoreDNS pod which
will then take over resolution of those 2 URLs
---
 pkg/controller/template/render.go             |  4 --
 .../files/usr-local-bin-update-etc-hosts.yaml | 11 ++++++
 .../units/gcp-update-etc-hosts.service.yaml   | 39 +++++++++++++++++++
 3 files changed, 50 insertions(+), 4 deletions(-)
 create mode 100644 templates/common/gcp/files/usr-local-bin-update-etc-hosts.yaml
 create mode 100644 templates/common/gcp/units/gcp-update-etc-hosts.service.yaml

diff --git a/pkg/controller/template/render.go b/pkg/controller/template/render.go
index 2fd20f39e0..d57070eb88 100644
--- a/pkg/controller/template/render.go
+++ b/pkg/controller/template/render.go
@@ -11,7 +11,6 @@ import (
 	"strings"
 	"text/template"
 
-	"github.com/sirupsen/logrus"
 	"k8s.io/klog/v2"
 
 	configv1 "github.com/openshift/api/config/v1"
@@ -782,16 +781,13 @@ func cloudPlatformIngressLoadBalancerIPs(cfg RenderConfig) (interface{}, error)
 // cloudPlatformLBIPAvailable returns true when DNSType is set to `ClusterHosted`
 // and LB IPs are provided as part of `PlatformStatus`.
 func cloudPlatformLBIPAvailable(cfg RenderConfig) bool {
-	logrus.Infof("Inside cloudPlatformLBIPAvailable")
 	if cfg.Infra.Status.PlatformStatus != nil {
 		switch cfg.Infra.Status.PlatformStatus.Type {
 		case configv1.GCPPlatformType:
 			switch cloudPlatformLoadBalancerIPState(cfg) {
 			case availableLBIPState:
-				logrus.Infof("LB IPs available")
 				return true
 			default:
-				logrus.Infof("LB IPs not available")
 				return false
 			}
 		case configv1.AWSPlatformType:
diff --git a/templates/common/gcp/files/usr-local-bin-update-etc-hosts.yaml b/templates/common/gcp/files/usr-local-bin-update-etc-hosts.yaml
new file mode 100644
index 0000000000..0dcfe5fbb6
--- /dev/null
+++ b/templates/common/gcp/files/usr-local-bin-update-etc-hosts.yaml
@@ -0,0 +1,11 @@
+mode: 0755
+path: "/usr/local/bin/update-etc-hosts"
+contents:
+  inline: |
+    #!/bin/bash
+    etc_hosts_config_filename="/etc/conf.d/etc-hosts.conf"
+    if [ ! -f "$etc_hosts_config_filename" ]; then
+      exit 0
+    fi
+    cat /etc/conf.d/etc-hosts.conf >> /etc/hosts
+    echo "Done updating /etc/hosts"
diff --git a/templates/common/gcp/units/gcp-update-etc-hosts.service.yaml b/templates/common/gcp/units/gcp-update-etc-hosts.service.yaml
new file mode 100644
index 0000000000..49d464ce6b
--- /dev/null
+++ b/templates/common/gcp/units/gcp-update-etc-hosts.service.yaml
@@ -0,0 +1,39 @@
+name: gcp-update-etc-hosts.service
+enabled: {{if and (eq .Infra.Status.PlatformStatus.Type "GCP") (.Infra.Status.PlatformStatus.GCP) (.Infra.Status.PlatformStatus.GCP.CloudLoadBalancerConfig) (eq .Infra.Status.PlatformStatus.GCP.CloudLoadBalancerConfig.DNSType "ClusterHosted") }}true{{else}}false{{end}}
+contents: |
+  [Unit]
+  Description=Update Default GCP /etc/hosts
+  # We don't need to do this on the firstboot
+  After=firstboot-osupdate.target
+  # Wait for NetworkManager to report it's online
+  After=NetworkManager-wait-online.service
+  # Run before kubelet
+  Before=kubelet-dependencies.target
+
+  [Service]
+  # Need oneshot to delay kubelet
+  Type=oneshot
+  ExecStart=/bin/bash -c " \
+  {{ if and (cloudPlatformLBIPAvailable .) (gt (len (cloudPlatformAPIIntLoadBalancerIPs .)) 0) }} \
+  apiIntLBIPs={{ cloudPlatformAPIIntLoadBalancerIPs . }} \
+  {{ end }} \
+  {{ if and (cloudPlatformLBIPAvailable .) (gt (len (cloudPlatformAPILoadBalancerIPs .)) 0) }} \
+  apiLBIPs={{ cloudPlatformAPILoadBalancerIPs . }} \
+  {{ end }} \
+  if [ -z "$apiLBIPs" ]; then \
+    # apiLBIPs will not be set on private clusters
+    apiLBIPs=$apiIntLBIPs \
+  fi \
+  apiServerURL={{ .Infra.Status.APIServerURL }} \
+  apiServerIntURL={{ .Infra.Status.APIServerInternalURL }} \
+  mkdir -p /etc/conf.d \
+  cat <<EOF | tee /etc/conf.d/etc-hosts.conf \
+  # Added by OpenShift \
+  ${apiLBIPs[0]}    ${apiServerURL} \
+  ${apiIntLBIPs[0]}    ${apiServerIntURL} \
+  EOF \
+  # Update /etc/hosts \
+  /usr/local/bin/update-etc-hosts"
+
+  [Install]
+  RequiredBy=kubelet-dependencies.target