How to add additional search domains and nameservers in OCP 4

Solution Verified - Updated -

Issue

  • How to add additional search domain for the cluster DNS in order to resolve domains that belong to the cluster base domain in OCP IPI installation.
  • The Domain Search List provided by DHCP does not contain all the required domains. How can we add additional?
  • Is it possible to modify the domain search in /etc/resolv.conf?
  • After an application is migrated to OpenShift they are failing to connect to outside resources due to the application not being configured to use fully qualified domain names.
  • Is it possible to modify the nameservers in /etc/resolv.conf?
  • Updating nameservers by creating machine configs causing MCP to go into a degraded state causing the below errors:

    E0928 15:37:57.579907    3108 writer.go:135] Marking Degraded due to: unexpected on-disk state validating against rendered-infra-cd76ce447a127cf588ccc839140855f8
    I0928 15:38:05.618367    3108 daemon.go:771] Current config: rendered-infra-19f5b87200b70348e167ddd9f3fe3138
    I0928 15:38:05.618396    3108 daemon.go:772] Desired config: rendered-infra-cd76ce447a127cf588ccc839140855f8
    I0928 15:38:05.631354    3108 update.go:1404] Disk currentConfig rendered-infra-cd76ce447a127cf588ccc839140855f8 overrides node annotation rendered-infra-19f5b87200b70348e167ddd9f3fe3138
    I0928 15:38:05.635347    3108 daemon.go:1014] Validating against pending config rendered-infra-cd76ce447a127cf588ccc839140855f8
    E0928 15:38:06.388077    3108 daemon.go:1413] content mismatch for file /etc/resolv.conf (-want +got):
    bytes.Join({
    -       "search example.com",
    +       "# Generated by KNI resolv prepender NM dispatcher script",
    +       "search test.example.com",
    +      "nameserver 5.6.7.8",
            "nameserver 1.2.3.4,
    

Environment

  • Red Hat OpenShift Container Platform (RHOCP)
    • 4.x

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