HTTP01

cert-manager uses your existing Ingress or Gateway configuration in order to solve HTTP01 challenges.

Configuring the HTTP01 Ingress solver

This page contains details on the different options available on the Issuer resource's HTTP01 challenge solver configuration. For more information on configuring ACME issuers and their API format, read the ACME Issuers documentation.

You can read about how the HTTP01 challenge type works on the Let's Encrypt challenge types page.

Here is an example of a simple HTTP01 ACME issuer with more options for configuration below:

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: example-issuer
spec:
  acme:
    server: https://acme-staging-v02.api.letsencrypt.org/directory
    privateKeySecretRef:
      name: example-issuer-account-key
    solvers:
    - http01:
        ingress:
          class: nginx

Options

The HTTP01 Issuer supports a number of additional options. For full details on the range of options available, read the reference documentation.

class

If the class field is specified, cert-manager will create new Ingress resources in order to route traffic to the acmesolver pods, which are responsible for responding to ACME challenge validation requests.

If this field is not specified, and name is also not specified, cert-manager will default to create new Ingress resources but will not set the ingress class on these resources, meaning all ingress controllers installed in your cluster will serve traffic for the challenge solver, potentially incurring additional cost.

name

If the name field is specified, cert-manager will edit the named ingress resource in order to solve HTTP01 challenges.

This is useful for compatibility with ingress controllers such as ingress-gce, which utilize a unique IP address for each Ingress resource created.

This mode should be avoided when using ingress controllers that expose a single IP for all ingress resources, as it can create compatibility problems with certain ingress-controller specific annotations.

serviceType

In rare cases it might be not possible/desired to use NodePort as type for the HTTP01 challenge response service, e.g. because of Kubernetes limit restrictions. To define which Kubernetes service type to use during challenge response specify the following HTTP01 configuration:

http01:
      ingress:
        # Valid values are ClusterIP and NodePort
        serviceType: ClusterIP

By default, type NodePort will be used when you don't set HTTP01 or when you set serviceType to an empty string. Normally there's no need to change this.

podTemplate

You may wish to change or add to the labels and annotations of solver pods. These can be configured under the metadata field under podTemplate.

Similarly, you can set the nodeSelector, tolerations and affinity of solver pods by configuring under the spec field of the podTemplate. No other spec fields can be edited.

An example of how you could configure the template is as so:

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: ...
spec:
  acme:
    server: ...
    privateKeySecretRef:
      name: ...
    solvers:
    - http01:
        ingress:
          podTemplate:
            metadata:
              labels:
                foo: "bar"
                env: "prod"
            spec:
              nodeSelector:
                bar: baz

The added labels and annotations will merge on top of the cert-manager defaults, overriding entries with the same key.

No other fields of the podTemplate exist.

ingressTemplate

It is possible to add labels and annotations to the solver ingress resources. It can be really useful when you are managing several Ingress Controllers across your cluster and you want to make sure that the right one will pick up and expose the solver (for the upcoming challenge to resolve). These can be configured under the metadata field under ingressTemplate:

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: ...
spec:
  acme:
    server: ...
    privateKeySecretRef:
      name: ...
    solvers:
    - http01:
        ingress:
          ingressTemplate:
            metadata:
              labels:
                foo: "bar"
              annotations:
                "nginx.ingress.kubernetes.io/whitelist-source-range": "0.0.0.0/0,::/0"
                "nginx.org/mergeable-ingress-type": "minion"
                "traefik.ingress.kubernetes.io/frontend-entry-points": "http"

The added labels and annotations will merge on top of the cert-manager defaults, overriding entries with the same key.

No other fields of the ingress can be edited.

Configuring the HTTP-01 Gateway API solver

FEATURE STATE: cert-manager 1.5 [alpha]

The Gateway and HTTPRoute resources are part of the Gateway API, a set of CRDs that you install on your Kubernetes cluster that provide various improvements over the Ingress API.

kubectl kustomize "github.com/kubernetes-sigs/gateway-api/config/crd?ref=v0.4.1" | kubectl apply -f -

kubectl rollout restart deployment cert-manager -n cert-manager

The Gateway API HTTPRoute HTTP-01 solver creates a temporary HTTPRoute using the given labels. These labels must match a Gateway that contains a listener on port 80.

Here is an example of a HTTP-01 ACME Issuer using the Gateway API:

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: letsencrypt
  namespace: default
spec:
  acme:
    solvers:
      - http01:
          gatewayHTTPRoute:
            parentRefs:
              - name: traefik
                namespace: traefik
                kind: Gateway

The Issuer relies on an existing Gateway present on the cluster. cert-manager does not edit Gateway resources.

For example, the following Gateway will allow the Issuer to solve the challenge:

apiVersion: gateway.networking.k8s.io/v1alpha2
kind: Gateway
metadata:
  name: traefik
  namespace: traefik
spec:
  gatewayClassName: traefik
  listeners:
  - name: http
    protocol: HTTP
    port: 80
    allowedRoutes:
        namespaces:
          from: All

In the above example, the Gateway has been specifically created for the purpose of solving HTTP-01 challenges, but you can also choose to re-use your existing Gateway, as long as it has a listener on port 80.

The labels on your Issuer may reference a Gateway that is on a separate namespace, as long as the Gateway's port 80 listener is configured with from: All. Note that the Certificate will still be created on the same namespace as the Issuer, which means that you won't be able to reference this Secret in the above-mentioned Gateway.

When the above Issuer is presented with a Certificate, cert-manager creates the temporary HTTPRoute. For example, with the following Certificate:

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: example-tls
  namespace: default
spec:
  issuerRef:
    name: letsencrypt
  dnsNames:
  - example.net

You will see an HTTPRoute appear:

kind: HTTPRoute
metadata:
  name: cm-acme-http-solver-gdhvg
  namespace: default
spec:
  parentRefs:
    - name: traefik
      namespace: traefik
      kind: Gateway
  hostnames:
  - example.net
  rules:
  - forwardTo:
    - port: 8089
      serviceName: cm-acme-http-solver-gdhvg
      weight: 1
    matches:
    - path:
        type: Exact
        value: /.well-known/acme-challenge/YadC4gaAzqEPU1Yea0D2MrzvNRWiBCtUizCtpiRQZqI

After the Certificate is issued, the HTTPRoute is deleted.

labels

These labels are copied into the temporary HTTPRoute created by cert-manager for solving the HTTP-01 challenge. These labels must match one of the Gateway resources on your cluster. The matched Gateway have a listener on port 80.

Note that when the labels do not match any Gateway on your cluster, cert-manager will create the temporary HTTPRoute challenge and nothing will happen.

serviceType

This field has the same meaning as the http01.ingress.serviceType.

Setting Nameservers for HTTP-01 solver propagation checks

cert-manager will perform reachability tests before attempting a HTT01 challenge. By default cert-manager will use the recursive nameservers taken from /etc/resolv.conf to query the challenge URL.

If this is not desired (for example with split-horizon DNS), the cert-manager controller exposes a flag that allows you alter this behavior:

--acme-http01-solver-nameservers Comma separated string with host and port of the recursive nameservers cert-manager should query.

Example usage:

--acme-http01-solver-nameservers="8.8.8.8:53,1.1.1.1:53"

If you're using the cert-manager helm chart, you can set recursive nameservers through .Values.extraArgs or at the command at helm install/upgrade time with --set:

--set 'extraArgs={--acme-http01-solver-nameservers=8.8.8.8:53\,1.1.1.1:53}'