Securing NGINX-ingress

This tutorial will detail how to install and secure ingress to your cluster using NGINX.

Step 0 - Install Helm Client

Skip this section if you have helm installed.

The easiest way to install cert-manager is to use Helm, a templating and deployment tool for Kubernetes resources.

First, ensure the Helm client is installed following the Helm installation instructions.

For example, on MacOS:

$ brew install kubernetes-helm

Step 1 - Install Tiller

Skip this section if you have Tiller set-up. Ignore this part for Helm version 3

Tiller is Helm's server-side component, which the helm client uses to deploy resources.

Deploying resources is a privileged operation; in the general case requiring arbitrary privileges. With this example, we give Tiller complete control of the cluster. View the documentation on securing helm for details on setting up appropriate permissions for your environment.

Create a ServiceAccount for Tiller:

$ kubectl create serviceaccount tiller --namespace=kube-system
serviceaccount "tiller" created

Grant the tiller service account cluster admin privileges:

$ kubectl create clusterrolebinding tiller-admin --serviceaccount=kube-system:tiller --clusterrole=cluster-admin
clusterrolebinding.rbac.authorization.k8s.io "tiller-admin" created

Install tiller with the tiller service account:

$ helm init --service-account=tiller
$HELM_HOME has been configured at /Users/myaccount/.helm.

Tiller (the Helm server-side component) has been installed into your Kubernetes Cluster.

Please note: by default, Tiller is deployed with an insecure 'allow unauthenticated users' policy.
To prevent this, run `helm init` with the --tiller-tls-verify flag.
For more information on securing your installation see: https://docs.helm.sh/using_helm/#securing-your-helm-installation
Happy Helming!

Step 2 - Deploy the NGINX Ingress Controller

A kubernetes ingress controller is designed to be the access point for HTTP and HTTPS traffic to the software running within your cluster. The ingress-nginx-controller does this by providing an HTTP proxy service supported by your cloud provider's load balancer.

You can get more details about ingress-nginx and how it works from the documentation for ingress-nginx.

Add the latest helm repository for the ingress-nginx

$ helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx

Update the helm repository with the latest charts:

$ helm repo update
Hang tight while we grab the latest from your chart repositories...
...Skip local chart repository
...Successfully got an update from the "stable" chart repository
...Successfully got an update from the "ingress-nginx" chart repository
...Successfully got an update from the "coreos" chart repository
Update Complete. ⎈ Happy Helming!⎈

Use helm to install an NGINX Ingress controller:

# for helm version 2
$ helm install ingress-nginx/ingress-nginx --name quickstart

# for helm version 3
$ helm install quickstart ingress-nginx/ingress-nginx

NAME: quickstart
LAST DEPLOYED: Wed Feb  3 12:55:58 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
The ingress-nginx controller has been installed.
It may take a few minutes for the LoadBalancer IP to be available.
You can watch the status by running 'kubectl --namespace default get services -o wide -w quickstart-ingress-nginx-controller'

An example Ingress that makes use of the controller:

  apiVersion: networking.k8s.io/v1beta1
  kind: Ingress
  metadata:
    annotations:
      kubernetes.io/ingress.class: nginx
    name: example
    namespace: foo
  spec:
    rules:
      - host: www.example.com
        http:
          paths:
            - backend:
                serviceName: exampleService
                servicePort: 80
              path: /
    # This section is only required if TLS is to be enabled for the Ingress
    tls:
        - hosts:
            - www.example.com
          secretName: example-tls

If TLS is enabled for the Ingress, a Secret containing the certificate and key must also be provided:

  apiVersion: v1
  kind: Secret
  metadata:
    name: example-tls
    namespace: foo
  data:
    tls.crt: <base64 encoded cert>
    tls.key: <base64 encoded key>
  type: kubernetes.io/tls

It can take a minute or two for the cloud provider to provide and link a public IP address. When it is complete, you can see the external IP address using the kubectl command:

$ kubectl get svc
NAME                                            TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)                      AGE
kubernetes                                      ClusterIP      10.0.0.1       <none>        443/TCP                      13m
quickstart-ingress-nginx-controller             LoadBalancer   10.0.114.241   <pending>     80:31635/TCP,443:30062/TCP   8m16s
quickstart-ingress-nginx-controller-admission   ClusterIP      10.0.188.24    <none>        443/TCP                      8m16s

This command shows you all the services in your cluster (in the default namespace), and any external IP addresses they have. When you first create the controller, your cloud provider won't have assigned and allocated an IP address through the LoadBalancer yet. Until it does, the external IP address for the service will be listed as <pending>.

Your cloud provider may have options for reserving an IP address prior to creating the ingress controller and using that IP address rather than assigning an IP address from a pool. Read through the documentation from your cloud provider on how to arrange that.

Step 3 - Assign a DNS name

The external IP that is allocated to the ingress-controller is the IP to which all incoming traffic should be routed. To enable this, add it to a DNS zone you control, for example as www.example.com.

This quick-start assumes you know how to assign a DNS entry to an IP address and will do so.

Step 4 - Deploy an Example Service

Your service may have its own chart, or you may be deploying it directly with manifests. This quick-start uses manifests to create and expose a sample service. The example service uses kuard, a demo application which makes an excellent back-end for examples.

The quick-start example uses three manifests for the sample. The first two are a sample deployment and an associated service:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kuard
spec:
  selector:
    matchLabels:
      app: kuard
  replicas: 1
  template:
    metadata:
      labels:
        app: kuard
    spec:
      containers:
      - image: gcr.io/kuar-demo/kuard-amd64:1
        imagePullPolicy: Always
        name: kuard
        ports:
        - containerPort: 8080

apiVersion: v1
kind: Service
metadata:
  name: kuard
spec:
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP
  selector:
    app: kuard

You can create download and reference these files locally, or you can reference them from the GitHub source repository for this documentation. To install the example service from the tutorial files straight from GitHub, you may use the commands:

$ kubectl apply -f https://netlify.cert-manager.io/docs/tutorials/acme/example/deployment.yaml
deployment.extensions "kuard" created

$ kubectl apply -f https://netlify.cert-manager.io/docs/tutorials/acme/example/service.yaml
service "kuard" created

An ingress resource is what Kubernetes uses to expose this example service outside the cluster. You will need to download and modify the example manifest to reflect the domain that you own or control to complete this example.

A sample ingress you can start with is:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: kuard
  annotations:
    kubernetes.io/ingress.class: "nginx"    
    #cert-manager.io/issuer: "letsencrypt-staging"

spec:
  tls:
  - hosts:
    - example.example.com
    secretName: quickstart-example-tls
  rules:
  - host: example.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: kuard
            port:
              number: 80

You can download the sample manifest from GitHub , edit it, and submit the manifest to Kubernetes with the command. Edit the file in your editor, and once it is saved:

$ kubectl create --edit -f https://netlify.cert-manager.io/docs/tutorials/acme/example/ingress.yaml
ingress.extensions "kuard" created

Note: The ingress example we show above has a host definition within it. The ingress-nginx-controller will route traffic when the hostname requested matches the definition in the ingress. You can deploy an ingress without a host definition in the rule, but that pattern isn't usable with a TLS certificate, which expects a fully qualified domain name.

Once it is deployed, you can use the command kubectl get ingress to see the status of the ingress:

NAME      HOSTS     ADDRESS   PORTS     AGE
kuard     *                   80, 443   17s

It may take a few minutes, depending on your service provider, for the ingress to be fully created. When it has been created and linked into place, the ingress will show an address as well:

NAME      HOSTS     ADDRESS         PORTS     AGE
kuard     *         203.0.113.2   80        9m

Note: The IP address on the ingress may not match the IP address that the ingress-nginx-controller has. This is fine, and is a quirk/implementation detail of the service provider hosting your Kubernetes cluster. Since we are using the ingress-nginx-controller instead of any cloud-provider specific ingress backend, use the IP address that was defined and allocated for the quickstart-ingress-nginx-controller LoadBalancer resource as the primary access point for your service.

Make sure the service is reachable at the domain name you added above, for example http://www.example.com. The simplest way is to open a browser and enter the name that you set up in DNS, and for which we just added the ingress.

You may also use a command line tool like curl to check the ingress.

$ curl -kivL -H 'Host: www.example.com' 'http://203.0.113.2'

The options on this curl command will provide verbose output, following any redirects, show the TLS headers in the output, and not error on insecure certificates. With ingress-nginx-controller, the service will be available with a TLS certificate, but it will be using a self-signed certificate provided as a default from the ingress-nginx-controller. Browsers will show a warning that this is an invalid certificate. This is expected and normal, as we have not yet used cert-manager to get a fully trusted certificate for our site.

Warning: It is critical to make sure that your ingress is available and responding correctly on the internet. This quick-start example uses Let's Encrypt to provide the certificates, which expects and validates both that the service is available and that during the process of issuing a certificate uses that validation as proof that the request for the domain belongs to someone with sufficient control over the domain.

Step 5 - Deploy Cert Manager

We need to install cert-manager to do the work with Kubernetes to request a certificate and respond to the challenge to validate it. We can use Helm or plain Kubernetes manifest to install cert-manager.

Read the getting started guide to install cert-manager using your preferred method.

Cert-manager uses two different custom resources, also known as CRD's, to configure and control how it operates, as well as share status of its operation. These two resources are:

An Issuer is the definition for where cert-manager will get request TLS certificates. An Issuer is specific to a single namespace in Kubernetes, and a ClusterIssuer is meant to be a cluster-wide definition for the same purpose.

Note that if you're using this document as a guide to configure cert-manager for your own Issuer, you must create the Issuers in the same namespace as your Ingress resources by adding -n my-namespace to your kubectl create commands. Your other option is to replace your Issuers with ClusterIssuers. ClusterIssuer resources apply across all Ingress resources in your cluster and don't have this namespace-matching requirement. In that case, remember to update the Ingress annotation cert-manager.io/issuer with cert-manager.io/cluster-issuer. To debug such failures, follow the Troubleshooting Issuing ACME Certificates guide.

More information on the differences between Issuers and ClusterIssuers and when you might choose to use each can be found here.

A certificate is the resource that cert-manager uses to expose the state of a request as well as track upcoming expiration.

Step 6 - Configure Let's Encrypt Issuer

We will set up two issuers for Let's Encrypt in this example. The Let's Encrypt production issuer has very strict rate limits. When you are experimenting and learning, it is very easy to hit those limits, and confuse rate limiting with errors in configuration or operation.

Because of this, we will start with the Let's Encrypt staging issuer, and once that is working switch to a production issuer.

Create this definition locally and update the email address to your own. This email required by Let's Encrypt and used to notify you of certificate expiration and updates.

apiVersion: cert-manager.io/v1
   kind: Issuer
   metadata:
     name: letsencrypt-staging
   spec:
     acme:
       # The ACME server URL
       server: https://acme-staging-v02.api.letsencrypt.org/directory
       # Email address used for ACME registration
       email: user@example.com
       # Name of a secret used to store the ACME account private key
       privateKeySecretRef:
         name: letsencrypt-staging
       # Enable the HTTP-01 challenge provider
       solvers:
       - http01:
           ingress:
             class:  nginx

Once edited, apply the custom resource:

$ kubectl create --edit -f https://cert-manager.io/docs/tutorials/acme/example/staging-issuer.yaml
issuer.cert-manager.io "letsencrypt-staging" created

Also create a production issuer and deploy it. As with the staging issuer, you will need to update this example and add in your own email address.

apiVersion: cert-manager.io/v1
   kind: Issuer
   metadata:
     name: letsencrypt-prod
   spec:
     acme:
       # The ACME server URL
       server: https://acme-v02.api.letsencrypt.org/directory
       # Email address used for ACME registration
       email: user@example.com
       # Name of a secret used to store the ACME account private key
       privateKeySecretRef:
         name: letsencrypt-prod
       # Enable the HTTP-01 challenge provider
       solvers:
       - http01:
           ingress:
             class: nginx

$ kubectl create --edit -f https://cert-manager.io/docs/tutorials/acme/example/production-issuer.yaml
issuer.cert-manager.io "letsencrypt-prod" created

Both of these issuers are configured to use the HTTP01 challenge provider.

Check on the status of the issuer after you create it:

$ kubectl describe issuer letsencrypt-staging
Name:         letsencrypt-staging
Namespace:    default
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"cert-manager.io/v1","kind":"Issuer","metadata":{"annotations":{},"name":"letsencrypt-staging","namespace":"default"},(...)}
API Version:  cert-manager.io/v1
Kind:         Issuer
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-11-17T18:03:54Z
  Generation:          0
  Resource Version:    9092
  Self Link:           /apis/cert-manager.io/v1/namespaces/default/issuers/letsencrypt-staging
  UID:                 25b7ae77-ea93-11e8-82f8-42010a8a00b5
Spec:
  Acme:
    Email:  email@example.com
    Private Key Secret Ref:
      Key:
      Name:  letsencrypt-staging
    Server:  https://acme-staging-v02.api.letsencrypt.org/directory
    Solvers:
      Http 01:
        Ingress:
          Class:  nginx
Status:
  Acme:
    Uri:  https://acme-staging-v02.api.letsencrypt.org/acme/acct/7374163
  Conditions:
    Last Transition Time:  2018-11-17T18:04:00Z
    Message:               The ACME account was registered with the ACME server
    Reason:                ACMEAccountRegistered
    Status:                True
    Type:                  Ready
Events:                    <none>

You should see the issuer listed with a registered account.

Step 7 - Deploy a TLS Ingress Resource

With all the prerequisite configuration in place, we can now do the pieces to request the TLS certificate. There are two primary ways to do this: using annotations on the ingress with ingress-shim or directly creating a certificate resource.

In this example, we will add annotations to the ingress, and take advantage of ingress-shim to have it create the certificate resource on our behalf. After creating a certificate, the cert-manager will update or create a ingress resource and use that to validate the domain. Once verified and issued, cert-manager will create or update the secret defined in the certificate.

Note: The secret that is used in the ingress should match the secret defined in the certificate. There isn't any explicit checking, so a typo will result in the ingress-nginx-controller falling back to its self-signed certificate. In our example, we are using annotations on the ingress (and ingress-shim) which will create the correct secrets on your behalf.

Edit the ingress add the annotations that were commented out in our earlier example:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: kuard
  annotations:
    kubernetes.io/ingress.class: "nginx"    
    cert-manager.io/issuer: "letsencrypt-staging"

spec:
  tls:
  - hosts:
    - example.example.com
    secretName: quickstart-example-tls
  rules:
  - host: example.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: kuard
            port:
              number: 80

and apply it:

$ kubectl create --edit -f https://cert-manager.io/docs/tutorials/acme/example/ingress-tls.yaml
ingress.extensions "kuard" configured

Cert-manager will read these annotations and use them to create a certificate, which you can request and see:

$ kubectl get certificate
NAME                     READY   SECRET                   AGE
quickstart-example-tls   True    quickstart-example-tls   16m

Cert-manager reflects the state of the process for every request in the certificate object. You can view this information using the kubectl describe command:

$ kubectl describe certificate quickstart-example-tls
Name:         quickstart-example-tls
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  cert-manager.io/v1
Kind:         Certificate
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-11-17T17:58:37Z
  Generation:          0
  Owner References:
    API Version:           networking.k8s.io/v1
    Block Owner Deletion:  true
    Controller:            true
    Kind:                  Ingress
    Name:                  kuard
    UID:                   a3e9f935-ea87-11e8-82f8-42010a8a00b5
  Resource Version:        9295
  Self Link:               /apis/cert-manager.io/v1/namespaces/default/certificates/quickstart-example-tls
  UID:                     68d43400-ea92-11e8-82f8-42010a8a00b5
Spec:
  Dns Names:
    www.example.com
  Issuer Ref:
    Kind:       Issuer
    Name:       letsencrypt-staging
  Secret Name:  quickstart-example-tls
Status:
  Acme:
    Order:
      URL:  https://acme-staging-v02.api.letsencrypt.org/acme/order/7374163/13665676
  Conditions:
    Last Transition Time:  2018-11-17T18:05:57Z
    Message:               Certificate issued successfully
    Reason:                CertIssued
    Status:                True
    Type:                  Ready
Events:
  Type     Reason          Age                From          Message
  ----     ------          ----               ----          -------
  Normal   CreateOrder     9m                 cert-manager  Created new ACME order, attempting validation...
  Normal   DomainVerified  8m                 cert-manager  Domain "www.example.com" verified with "http-01" validation
  Normal   IssueCert       8m                 cert-manager  Issuing certificate...
  Normal   CertObtained    7m                 cert-manager  Obtained certificate from ACME server
  Normal   CertIssued      7m                 cert-manager  Certificate issued Successfully

The events associated with this resource and listed at the bottom of the describe results show the state of the request. In the above example the certificate was validated and issued within a couple of minutes.

Once complete, cert-manager will have created a secret with the details of the certificate based on the secret used in the ingress resource. You can use the describe command as well to see some details:

$ kubectl describe secret quickstart-example-tls
Name:         quickstart-example-tls
Namespace:    default
Labels:       cert-manager.io/certificate-name=quickstart-example-tls
Annotations:  cert-manager.io/alt-names=www.example.com
              cert-manager.io/common-name=www.example.com
              cert-manager.io/issuer-kind=Issuer
              cert-manager.io/issuer-name=letsencrypt-staging

Type:  kubernetes.io/tls

Data
====
tls.crt:  3566 bytes
tls.key:  1675 bytes

Now that we have confidence that everything is configured correctly, you can update the annotations in the ingress to specify the production issuer:

apiVersion: networking.k8s.io/v1 
kind: Ingress
metadata:
  name: kuard
  annotations:
    kubernetes.io/ingress.class: "nginx"    
    cert-manager.io/issuer: "letsencrypt-prod"

spec:
  tls:
  - hosts:
    - example.example.com
    secretName: quickstart-example-tls
  rules:
  - host: example.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: kuard
            port:
              number: 80

$ kubectl create --edit -f https://cert-manager.io/docs/tutorials/acme/example/ingress-tls-final.yaml
ingress.extensions "kuard" configured

You will also need to delete the existing secret, which cert-manager is watching and will cause it to reprocess the request with the updated issuer.

$ kubectl delete secret quickstart-example-tls
secret "quickstart-example-tls" deleted

This will start the process to get a new certificate, and using describe you can see the status. Once the production certificate has been updated, you should see the example KUARD running at your domain with a signed TLS certificate.

$ kubectl describe certificate quickstart-example-tls
Name:         quickstart-example-tls
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  cert-manager.io/v1
Kind:         Certificate
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-11-17T18:36:48Z
  Generation:          0
  Owner References:
    API Version:           networking.k8s.io/v1
    Block Owner Deletion:  true
    Controller:            true
    Kind:                  Ingress
    Name:                  kuard
    UID:                   a3e9f935-ea87-11e8-82f8-42010a8a00b5
  Resource Version:        283686
  Self Link:               /apis/cert-manager.io/v1/namespaces/default/certificates/quickstart-example-tls
  UID:                     bdd93b32-ea97-11e8-82f8-42010a8a00b5
Spec:
  Dns Names:
    www.example.com
  Issuer Ref:
    Kind:       Issuer
    Name:       letsencrypt-prod
  Secret Name:  quickstart-example-tls
Status:
  Conditions:
    Last Transition Time:  2019-01-09T13:52:05Z
    Message:               Certificate does not exist
    Reason:                NotFound
    Status:                False
    Type:                  Ready
Events:
  Type    Reason        Age   From          Message
  ----    ------        ----  ----          -------
  Normal  Generated     18s   cert-manager  Generated new private key
  Normal  OrderCreated  18s   cert-manager  Created Order resource "quickstart-example-tls-889745041"

You can see the current state of the ACME Order by running kubectl describe on the Order resource that cert-manager has created for your Certificate:

$ kubectl describe order quickstart-example-tls-889745041
...
Events:
  Type    Reason      Age   From          Message
  ----    ------      ----  ----          -------
  Normal  Created     90s   cert-manager  Created Challenge resource "quickstart-example-tls-889745041-0" for domain "www.example.com"

Here, we can see that cert-manager has created 1 'Challenge' resource to fulfill the Order. You can dig into the state of the current ACME challenge by running kubectl describe on the automatically created Challenge resource:

$ kubectl describe challenge quickstart-example-tls-889745041-0
...
Status:
  Presented:   true
  Processing:  true
  Reason:      Waiting for http-01 challenge propagation
  State:       pending
Events:
  Type    Reason     Age   From          Message
  ----    ------     ----  ----          -------
  Normal  Started    15s   cert-manager  Challenge scheduled for processing
  Normal  Presented  14s   cert-manager  Presented challenge using http-01 challenge mechanism

From above, we can see that the challenge has been 'presented' and cert-manager is waiting for the challenge record to propagate to the ingress controller. You should keep an eye out for new events on the challenge resource, as a 'success' event should be printed after a minute or so (depending on how fast your ingress controller is at updating rules):

$ kubectl describe challenge quickstart-example-tls-889745041-0
...
Status:
  Presented:   false
  Processing:  false
  Reason:      Successfully authorized domain
  State:       valid
Events:
  Type    Reason          Age   From          Message
  ----    ------          ----  ----          -------
  Normal  Started         71s   cert-manager  Challenge scheduled for processing
  Normal  Presented       70s   cert-manager  Presented challenge using http-01 challenge mechanism
  Normal  DomainVerified  2s    cert-manager  Domain "www.example.com" verified with "http-01" validation

Note: If your challenges are not becoming 'valid' and remain in the 'pending' state (or enter into a 'failed' state), it is likely there is some kind of configuration error. Read the Challenge resource reference docs for more information on debugging failing challenges.

Once the challenge(s) have been completed, their corresponding challenge resources will be deleted, and the 'Order' will be updated to reflect the new state of the Order:

$ kubectl describe order quickstart-example-tls-889745041
...
Events:
  Type    Reason      Age   From          Message
  ----    ------      ----  ----          -------
  Normal  Created     90s   cert-manager  Created Challenge resource "quickstart-example-tls-889745041-0" for domain "www.example.com"
  Normal  OrderValid  16s   cert-manager  Order completed successfully

Finally, the 'Certificate' resource will be updated to reflect the state of the issuance process. If all is well, you should be able to 'describe' the Certificate and see something like the below:

$ kubectl describe certificate quickstart-example-tls
Status:
  Conditions:
    Last Transition Time:  2019-01-09T13:57:52Z
    Message:               Certificate is up to date and has not expired
    Reason:                Ready
    Status:                True
    Type:                  Ready
  Not After:               2019-04-09T12:57:50Z
Events:
  Type    Reason         Age                  From          Message
  ----    ------         ----                 ----          -------
  Normal  Generated      11m                  cert-manager  Generated new private key
  Normal  OrderCreated   11m                  cert-manager  Created Order resource "quickstart-example-tls-889745041"
  Normal  OrderComplete  10m                  cert-manager  Order "quickstart-example-tls-889745041" completed successfully