DNS and Naming Scheme

An OpenShift 4 cluster requires using a specific DNS scheme which is described on this page. Most of the values are automatically generated and can’t be changed.

User selectable values

<base domain>: The base domain for the cluster (input by the customer). If the customer doesn’t provide a specific base domain, VSHN uses vshnmanaged.net as the base domain.

Automatically generated values

<cluster id>: The Project Syn Lieutenant cluster id of the cluster. The cluster ID can be generated by the Lieutenant API. The cluster ID is always prefixed with c-. By default, VSHN will suggest a cluster ID that reflects the customer and stage of the cluster, for example c-company-test1

<role>

Machine role. One of master, infra, worker and lb. Other roles possible when required by the customer (special node groups for builds, GPU support etc.).

<#>

An automatically, randomly defined character sequence with four digits.

<index>

A zero indexed incrementing number.

<cluster domain>

<cluster id>.<base domain>

<hostname>

The fully qualified domain name of machines belonging to the cluster.

`<role><#>.<cluster domain>`

This will only be used for naming the machines. No DNS records will be created.

<external api>

OpenShift API URL to be used by clients external to the cluster.

`api.<cluster domain>`

<internal api>

OpenShift API URL to be used by clients internal to the cluster.

`api-int.<cluster domain>`

<ingress floating IP>

The floating IP on which the applications are exposed.

`ingress.<cluster-domain>

<egress floating IP>

The floating IP to which egress traffic is SNATed. Optional, but always present for clusters running in a private network with a VSHN-managed default gateway.

`egress.<cluster-domain>`

<default app domain>

Usually a CNAME record to ingress.<cluster-domain>.

`*.apps.<cluster domain>`

<etcd>

etcd-<index>.<cluster domain>

<acme challenge>

DNS Resource Record of type TXT used for validating certificates using the DNS01 method. It must be possible to create these records programmatically with one of the APIs supported by cert-manager. By default, VSHN will use a self-hosted acme-dns instance to manage the TXT records.

`_acme-challenge.<default app domain | external api>`

The following DNS records must resolve publicly:

<acme challenge>
<cluster domain>
<default app domain>

<external api>

Everything else must resolve at least within the cluster's network.

Example

DNS Records

A full list of DNS records for the test cluster of company "summer-shadow" according to the definition on this page:

This example assumes that the customer doesn’t provide a custom base domain.

; Services
api.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x
api-int.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x
ingress.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x
egress.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x

*.apps.c-summer-shadow-2592.vshnmanaged.net IN CNAME ingress.c-summer-shadow-test1.example.com.

etcd-0.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x
etcd-1.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x
etcd-2.c-summer-shadow-test1.vshnmanaged.net IN A x.x.x.x

_acme-challenge.api.c-summer-shadow-test1.vshnmanaged.net IN CNAME <acme-dns-client-uuid>.acme-dns.vshn.net.
_acme-challenge.apps.c-summer-shadow-test1.vshnmanaged.net IN TXT <acme-dns-client-uuid>.acme-dns.vshn.net.

Hostnames

A full list of example hostnames for the test cluster of company "summer-shadow" according to the definition on this page:

infra-454b.c-summer-shadow-test1.vshnmanaged.net
infra-9031.c-summer-shadow-test1.vshnmanaged.net
infra-c8f2.c-summer-shadow-test1.vshnmanaged.net

lb-5f52.c-summer-shadow-test1.vshnmanaged.net
lb-ba8f.c-summer-shadow-test1.vshnmanaged.net

master-0e9c.c-summer-shadow-test1.vshnmanaged.net
master-1a3c.c-summer-shadow-test1.vshnmanaged.net
master-e976.c-summer-shadow-test1.vshnmanaged.net

worker-4720.c-summer-shadow-test1.vshnmanaged.net
worker-7d32.c-summer-shadow-test1.vshnmanaged.net
worker-a640.c-summer-shadow-test1.vshnmanaged.net