Add delayBeforeCheck parameter. (#6734)

This is helpful in the scenario where you want to use dns-01
challenges in a public route53 zone, but your cluster's
resolver is using a private route53 zone and the initial TXT
check fails. This allows you to skip the check and instead
use a fixed delay before the ACME verification happens.

stable/traefik/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: traefik
-version: 1.40.0
+version: 1.41.0
 appVersion: 1.6.5
 description: A Traefik based Kubernetes ingress controller with Let's Encrypt support
 keywords:

stable/traefik/README.md

@@ -117,6 +117,7 @@ The following table lists the configurable parameters of the Traefik chart and t
 | `ssl.defaultKey`                       | Base64 encoded private key for the certificate above                                                                         | The private key for the certificate above         |
 | `acme.enabled`                         | Whether to use Let's Encrypt to obtain certificates                                                                          | `false`                                           |
 | `acme.challengeType`                   | Type of ACME challenge to perform domain validation. `tls-sni-01`, `http-01` or `dns-01`                                     | `tls-sni-01`                                      |
+| `acme.delayBeforeCheck`         | By default, the provider will verify the TXT DNS challenge record before letting ACME verify. If delayBeforeCheck is greater than zero, this check is delayed for the configured duration in seconds. Useful when Traefik cannot resolve external DNS queries. | `0` |
 | `acme.dnsProvider.name`                | Which DNS provider to use. See [here](https://github.com/xenolf/lego/tree/master/providers/dns) for the list of possible values. | `nil`                                         |
 | `acme.dnsProvider.$name`               | The configuration environment variables (encoded as a secret) needed for the DNS provider to do DNS challenge. See [here](#example-aws-route-53). | `{}`                         |
 | `acme.email`                           | Email address to be used in certificates obtained from Let's Encrypt                                                         | `admin@example.com`                               |

stable/traefik/templates/configmap.yaml

@@ -188,6 +188,9 @@ data:
     {{- if eq .Values.acme.challengeType "dns-01" }}
       [acme.dnsChallenge]
       provider = "{{ .Values.acme.dnsProvider.name }}"
+      {{- if .Values.acme.delayBeforeCheck }}
+      delayBeforeCheck = {{ .Values.acme.delayBeforeCheck }}
+      {{- end }}
     {{- else if eq .Values.acme.challengeType "http-01" }}
       [acme.httpChallenge]
       entryPoint = "http"

stable/traefik/values.yaml

@@ -138,6 +138,7 @@ acme:
   challengeType: tls-sni-01
   ## Configure dnsProvider to perform domain verification using dns challenge
   ## Applicable only if using the dns-01 challenge type
+  delayBeforeCheck: 0
   dnsProvider:
     name: nil
     auroradns: